MaxAdmin - Admin Interface
MaxAdmin - Admin Interface
The Maxscale Administrative & Monitoring Client Application
- Overview
- Configuring MariaDB MaxScale for MaxAdmin
- Running MaxAdmin
- Working With Administration Interface Users
- Getting Help
- Working with Services
- Working with Servers
- Working with Sessions
- Descriptor Control Blocks
- Working with Filters
- Working with Monitors
- MariaDB MaxScale Status Commands
- Administration Commands
- Runtime Configuration Changes
- Servers
- Listeners
- Monitors
- Tuning MariaDB MaxScale
Overview
MaxAdmin is a simple client interface that can be used to interact with the MariaDB MaxScale server, it allows the display of internal MariaDB MaxScale statistics, status and control of MariaDB MaxScale operations.
MaxAdmin supports
-
Interactive user sessions
-
Execution of one-off commands via command line arguments
-
Execution of command scripts
Configuring MariaDB MaxScale for MaxAdmin
In order to be able to use MaxAdmin, MariaDB MaxScale must be configured for it.
There are two ways MaxAdmin can connect to to MaxScale.
- Using a Unix domain socket.
- Using a hostname and port.
The first alternative is introduced in MaxScale 2.0 and is the secure and recommended way. The second alternative is available for backward compatibility, but is insecure and deprecated and will be removed in a future version of MaxScale.
An example configuration looks as follows:
[MaxAdmin] type=service router=cli [MaxAdmin Unix Listener] type=listener service=MaxAdmin protocol=maxscaled socket=default [MaxAdmin Inet Listener] type=listener service=MaxAdmin protocol=maxscaled address=localhost port=6603
In the configuration above, two listeners are created; one listening on the default Unix domain socket and one listening on the default port.
Which approach is used has other implications than just how the communication between MaxAdmin and MariaDB MaxScale is handled. In the former case, the authorization is based upon the Linux identity and in the latter case on explicitly created user accounts that have no relationship to the Linux accounts.
Note that if the socket path or port are changed, then MaxAdmin has to be
invoked with -S or -P respectively.
Running MaxAdmin
Depending on whether MariaDB MaxScale has been configured to use Unix domain sockets or internet sockets, MaxAdmin needs to be invoked slightly differently.
If Unix domain sockets are used, then MaxAdmin needs no additional arguments:
alice@host$ maxadmin MaxAdmin>
The above implies that the Linux user alice has been enabled to use MaxAdmin.
If internet sockets are used, then either the host, port, user or password has to be specified explicitly:
alice@host$ maxadmin -u maxscale-admin Password: MaxScale>
When internet sockets are enabled, initially it is possible to connect using
the username admin and the password mariadb. These remain in effect as long
as no other users have been created. As soon as the first user is added, the use
of admin/mariadb as login credentials is disabled.
If Unix domain sockets are used, then initially only root has access. MaxAdmin
usage can subsequently be enabled for other Linux users.
The MaxAdmin client application may be run in two different modes, either as an interactive command shell for executing commands against MariaDB MaxScale or by passing commands on the MaxAdmin command line itself.
Working With Administration Interface Users
What Users Have Been Defined?
In order to see the Linux users for whom MaxAdmin usage has been enabled and any explicitly created accounts, use the command show users.
MaxScale> show users Enabled Linux accounts (secure) : alice, bob, cecil Created network accounts (insecure): maxscale-admin MaxScale>
Please note that root will not be shown.
Enabling a Linux account
To enable MaxAdmin usage for a particular Linux account, use the command enable account. This command is passed a user name, which should be the same as that of an existing Linux user.
MaxScale> enable account bob
Note that it is not checked that the provided name indeed corresponds to an existing Linux account, so it is possible to enable an account that does not exist yet.
Note also that it is possible to enable a Linux account irrespective of how MaxAdmin has connected to MariaDB MaxScale. That is, the command is not restricted to MaxAdmin users connecting over a Unix domain socket.
Disabling a Linux account
To disable MaxAdmin usage for a particular Linux account, use the command disable account. This command is passed a user name, which should be a Linux user for whom MaxAdmin usage earlier has been enabled.
MaxScale> disable account bob
Note also that it is possible to disable a Linux account irrespective of how MaxAdmin has connected to MariaDB MaxScale. That is, the command is not restricted to MaxAdmin users connecting over a Unix domain socket.
Note that it is possible to disable the current user, but that will only affect
the next attempt to use MaxAdmin. root cannot be removed.
Add A New User
To add a new MaxAdmin user to be used when MaxAdmin connects over an internet socket, use the command add user. This command is passed a user name and a password.
MaxScale> add user maxscale-admin secretpwd User maxscale-admin has been successfully added. MaxScale>
Note that there is no difference in rights between an enabled Linux account and an explicitly created user.
Delete A User
To remove a user the command remove user is used and it is invoked with the username and password.
MaxScale> remove user maxscale-admin secretpwd User maxscale-admin has been successfully removed. MaxScale>
Note that it is possible to remove the current user, but that will only affect the next attempt to use MaxAdmin.
Command Line Switches
The MaxAdmin command accepts a number of options. See the output of
maxadmin --help for more details.
Interactive Operation
If no arguments other than the command line switches are passed to MaxAdmin it will enter its interactive mode of operation. Users will be prompted to enter commands with a MaxScale> prompt. The commands themselves are documented in the sections later in this document. A help system is available that will give some minimal details of the commands available.
Command history is available on platforms that support the libedit library. This allows the use of the up and down arrow keys to recall previous commands that have been executed by MaxAdmin. The default edit mode for the history is to emulate the vi commands, the behavior of libedit may however be customized using the .editrc file. To obtain the history of commands that have been executed use the inbuilt history command.
In interactive mode it is possible to execute a set of commands stored in an external file by using the source command. The command takes the argument of a filename which should contain a set of MariaDB MaxScale commands, one per line. These will be executed in the order they appear in the file.
Command Line Operation
MaxAdmin can also be used to execute commands that are passed on the command line, e.g.
-bash-4.1$ maxadmin -S /tmp/maxadmin.sock list services Password: Services. --------------------------+----------------------+--------+--------------- Service Name | Router Module | #Users | Total Sessions --------------------------+----------------------+--------+--------------- Test Service | readconnroute | 1 | 1 Split Service | readwritesplit | 1 | 1 Filter Service | readconnroute | 1 | 1 QLA Service | readconnroute | 1 | 1 Debug Service | debugcli | 1 | 1 CLI | cli | 2 | 27 --------------------------+----------------------+--------+--------------- -bash-4.1$
The single command is executed and MaxAdmin then terminates. If the -p option is not given then MaxAdmin will prompt for a password. If a MariaDB MaxScale command requires an argument which contains whitespace, for example a service name, that name should be quoted. The quotes will be preserved and used in the execution of the MariaDB MaxScale command.
-bash-4.1$ maxadmin show service "QLA Service"
Password:
Service 0x70c6a0
Service: QLA Service
Router: readconnroute (0x7ffff0f7ae60)
Number of router sessions: 0
Current no. of router sessions: 0
Number of queries forwarded: 0
Started: Wed Jun 25 10:08:23 2014
Backend databases
127.0.0.1:3309 Protocol: MySQLBackend
127.0.0.1:3308 Protocol: MySQLBackend
127.0.0.1:3307 Protocol: MySQLBackend
127.0.0.1:3306 Protocol: MySQLBackend
Users data: 0x724340
Total connections: 1
Currently connected: 1
-bash-4.1$
Command files may be executed by either calling MaxAdmin with the name of the file that contains the commands
maxadmin listall.ms
Or by using the #! mechanism to make the command file executable from the shell. To do this add a line at the start of your command file that contains the
! directive with the path of the MaxAdmin executable. Command options may also
be given in this line. For example to create a script file that runs a set of list commands
1 2 3 4 5 6 7 8 | #!/usr/bin/maxadmin list modules list servers list services list listeners list dcbs list sessions list filters |
Then simply set this file to have execute permissions and it may be run like any other command in the Linux shell.
The .maxadmin file
MaxAdmin supports a mechanism to set defaults for the command line switches via
a file in the home directory of the user. If a file named .maxadmin exists, it
will be read and parameters set according to the entries in that file.
This mechanism can be used to provide defaults to the command line options. If a
command line option is provided, it will still override the value in the
.maxadmin file.
The parameters than can be set are:
* 1.4: hostname, port, user and passwd
* 2.0.0 and 2.0.1: socket
* 2.0.2 onwards: socket, hostname, port, user and passwd (and as synonym password)
An example of a .maxadmin file that will alter the default socket path is:
socket=/somepath/maxadmin.socket
Note that if in 2.0.2 or later, a value for socket as well as any of the
internet socket related options, such as hostname, is provided in .maxadmin,
then socket takes precedence. In that case, provide at least one internet
socket related option on the command line to force MaxAdmin to use an internet
socket and thus the internet socket related options from .maxadmin.
The .maxadmin file may be made read only to protect any passwords written to
that file.
Getting Help
A help system is available that describes the commands available via the
administration interface. To obtain a list of all commands available simply type
the command help.
Available commands:
add:
add user - Add insecure account for using maxadmin over the network
add server - Add a new server to a service
remove:
remove user - Remove account for using maxadmin over the network
remove server - Remove a server from a service or a monitor
create:
create server - Create a new server
create listener - Create a new listener for a service
create monitor - Create a new monitor
destroy:
destroy server - Destroy a server
destroy listener - Destroy a listener
destroy monitor - Destroy a monitor
alter:
alter server - Alter server parameters
alter monitor - Alter monitor parameters
set:
set server - Set the status of a server
set pollsleep - Set poll sleep period
set nbpolls - Set non-blocking polls
set log_throttling - Set the log throttling configuration
clear:
clear server - Clear server status
disable:
disable log-priority - Disable a logging priority
disable sessionlog-priority - [Deprecated] Disable a logging priority for a particular session
disable root - Disable root access
disable feedback - Disable MaxScale feedback to notification service
disable syslog - Disable syslog logging
disable maxlog - Disable MaxScale logging
disable account - Disable Linux user
enable:
enable log-priority - Enable a logging priority
enable sessionlog-priority - [Deprecated] Enable a logging priority for a session
enable root - Enable root user access to a service
enable feedback - Enable MaxScale feedback to notification service
enable syslog - Enable syslog logging
enable maxlog - Enable MaxScale logging
enable account - Activate a Linux user account for MaxAdmin use
flush:
flush log - Flush the content of a log file and reopen it
flush logs - Flush the content of a log file and reopen it
list:
list clients - List all the client connections to MaxScale
list dcbs - List all active connections within MaxScale
list filters - List all filters
list listeners - List all listeners
list modules - List all currently loaded modules
list monitors - List all monitors
list services - List all services
list servers - List all servers
list sessions - List all the active sessions within MaxScale
list threads - List the status of the polling threads in MaxScale
list commands - List registered commands
reload:
reload config - Reload the configuration
reload dbusers - Reload the database users for a service
restart:
restart monitor - Restart a monitor
restart service - Restart a service
restart listener - Restart a listener
shutdown:
shutdown maxscale - Initiate a controlled shutdown of MaxScale
shutdown monitor - Stop a monitor
shutdown service - Stop a service
shutdown listener - Stop a listener
show:
show dcbs - Show all DCBs
show dbusers - [deprecated] Show user statistics
show authenticators - Show authenticator diagnostics for a service
show epoll - Show the polling system statistics
show eventstats - Show event queue statistics
show feedbackreport - Show the report of MaxScale loaded modules, suitable for Notification Service
show filter - Show filter details
show filters - Show all filters
show log_throttling - Show the current log throttling setting (count, window (ms), suppression (ms))
show modules - Show all currently loaded modules
show monitor - Show monitor details
show monitors - Show all monitors
show persistent - Show the persistent connection pool of a server
show server - Show server details
show servers - Show all servers
show serversjson - Show all servers in JSON
show services - Show all configured services in MaxScale
show service - Show a single service in MaxScale
show session - Show session details
show sessions - Show all active sessions in MaxScale
show tasks - Show all active housekeeper tasks in MaxScale
show threads - Show the status of the worker threads in MaxScale
show users - Show enabled Linux accounts
show version - Show the MaxScale version number
sync:
sync logs - Flush log files to disk
call:
call command - Call module command
Type `help COMMAND` to see details of each command.
Where commands require names as arguments and these names contain
whitespace either the \ character may be used to escape the whitespace
or the name may be enclosed in double quotes ".
To see more details on a particular command, and a list of the sub commands of the command, type help followed by the command name.
MaxScale> help list Available options to the `list` command: list clients - List all the client connections to MaxScale Usage: list clients ---------------------------------------------------------------------------- list dcbs - List all active connections within MaxScale Usage: list dcbs ---------------------------------------------------------------------------- list filters - List all filters Usage: list filters ---------------------------------------------------------------------------- list listeners - List all listeners Usage: list listeners ---------------------------------------------------------------------------- list modules - List all currently loaded modules Usage: list modules ---------------------------------------------------------------------------- list monitors - List all monitors Usage: list monitors ---------------------------------------------------------------------------- list services - List all services Usage: list services ---------------------------------------------------------------------------- list servers - List all servers Usage: list servers ---------------------------------------------------------------------------- list sessions - List all the active sessions within MaxScale Usage: list sessions ---------------------------------------------------------------------------- list threads - List the status of the polling threads in MaxScale Usage: list threads ---------------------------------------------------------------------------- list commands - List registered commands Usage: list commands [MODULE] [COMMAND] Parameters: MODULE Regular expressions for filtering module names COMMAND Regular expressions for filtering module command names Example: list commands my-module my-command MaxScale>
Working With Services
A service is a very important concept in MariaDB MaxScale as it defines the mechanism by which clients interact with MariaDB MaxScale and can attached to the backend databases. A number of commands exist that allow interaction with the services.
What Services Are Available?
The list services command can be used to discover what services are currently available within your MariaDB MaxScale configuration.
MaxScale> list services Services. --------------------------+-------------------+--------+----------------+------------------- Service Name | Router Module | #Users | Total Sessions | Backend databases --------------------------+-------------------+--------+----------------+------------------- RWSplit | readwritesplit | 1 | 1 | server1, server2, server3, server4 SchemaRouter | schemarouter | 1 | 1 | server1, server2, server3, server4 RWSplit-Hint | readwritesplit | 1 | 1 | server1, server2, server3, server4 ReadConn | readconnroute | 1 | 1 | server1 CLI | cli | 2 | 2 | --------------------------+-------------------+--------+----------------+------------------- MaxScale>
In order to determine which ports services are using then the list listeners command can be used.
MaxScale> list listeners Listeners. ----------------------+---------------------+--------------------+-----------------+-------+-------- Name | Service Name | Protocol Module | Address | Port | State ----------------------+---------------------+--------------------+-----------------+-------+-------- RWSplit-Listener | RWSplit | MySQLClient | * | 4006 | Running SchemaRouter-Listener | SchemaRouter | MySQLClient | * | 4010 | Running RWSplit-Hint-Listener | RWSplit-Hint | MySQLClient | * | 4009 | Running ReadConn-Listener | ReadConn | MySQLClient | * | 4008 | Running CLI-Listener | CLI | maxscaled | default | 0 | Running ----------------------+---------------------+--------------------+-----------------+-------+-------- MaxScale>
See Service Details
It is possible to see the details of an individual service using the show service command. This command should be passed the name of the service you wish to examine as an argument. Where a service name contains spaces characters there should either be escaped or the name placed in quotes.
MaxScale> show service RWSplit
Service: RWSplit
Router: readwritesplit
State: Started
use_sql_variables_in: all
slave_selection_criteria: LEAST_CURRENT_OPERATIONS
master_failure_mode: fail_instantly
max_slave_replication_lag: -1
retry_failed_reads: true
strict_multi_stmt: true
disable_sescmd_history: true
max_sescmd_history: 0
master_accept_reads: false
Number of router sessions: 0
Current no. of router sessions: 1
Number of queries forwarded: 0
Number of queries forwarded to master: 0 (0.00%)
Number of queries forwarded to slave: 0 (0.00%)
Number of queries forwarded to all: 0 (0.00%)
Started: Thu Apr 20 09:45:13 2017
Root user access: Disabled
Backend databases:
[127.0.0.1]:3000 Protocol: MySQLBackend Name: server1
[127.0.0.1]:3001 Protocol: MySQLBackend Name: server2
[127.0.0.1]:3002 Protocol: MySQLBackend Name: server3
[127.0.0.1]:3003 Protocol: MySQLBackend Name: server4
Total connections: 1
Currently connected: 1
MaxScale>
This allows the set of backend servers defined by the service to be seen along with the service statistics and other information.
Examining Service Users
MariaDB MaxScale provides an authentication model by which the client application authenticates with MariaDB MaxScale using the credentials they would normally use to with the database itself. MariaDB MaxScale loads the user data from one of the backend databases defined for the service. The show dbusers command can be used to examine the user data held by MariaDB MaxScale.
MaxScale> show dbusers RWSplit User names: @localhost @localhost.localdomain 14567USER@localhost monuser@localhost monuser@% 14609USER@localhost maxuser@localhost maxuser@% 14651USER@localhost maxtest@localhost maxtest@% 14693USER@localhost skysql@localhost skysql@% 14735USER@localhost cliuser@localhost cliuser@% repuser@localhost repuser@% MaxScale>
Reloading Service User Data
MariaDB MaxScale will automatically reload user data if there are failed authentication requests from client applications. This reloading is rate limited and triggered by missing entries in the MariaDB MaxScale table. If a user is removed from the backend database user table it will not trigger removal from the MariaDB MaxScale internal table. The reload dbusers command can be used to force the reloading of the user table within MariaDB MaxScale.
MaxScale> reload dbusers RWSplit Reloaded database users for service RWSplit. MaxScale>
Stopping A Service
It is possible to stop a service from accepting new connections by using the shutdown service command. This will not affect the connections that are already in place for a service, but will stop any new connections from being accepted.
MaxScale> shutdown service RWSplit MaxScale>
Restart A Stopped Service
A stopped service may be restarted by using the restart service command.
MaxScale> restart service RWSplit MaxScale>
Working With Servers
The server represents each of the instances of MariaDB or MySQL that a service may use.
What Servers Are Configured?
The command list servers can be used to display a list of all the servers configured within MariaDB MaxScale.
MaxScale> list servers Servers. -------------------+-----------------+-------+-------------+-------------------- Server | Address | Port | Connections | Status -------------------+-----------------+-------+-------------+-------------------- server1 | 127.0.0.1 | 3000 | 0 | Master, Running server2 | 127.0.0.1 | 3001 | 0 | Slave, Running server3 | 127.0.0.1 | 3002 | 0 | Slave, Running server4 | 127.0.0.1 | 3003 | 0 | Slave, Running -------------------+-----------------+-------+-------------+-------------------- MaxScale>
Server Details
It is possible to see more details regarding a given server using the show server command.
MaxScale> show server server2
Server 0x6501d0 (server2)
Server: 127.0.0.1
Status: Slave, Running
Protocol: MySQLBackend
Port: 3001
Server Version: 10.1.22-MariaDB
Node Id: 3001
Master Id: 3000
Slave Ids:
Repl Depth: 1
Number of connections: 0
Current no. of conns: 0
Current no. of operations: 0
MaxScale>
If the server has a non-zero value set for the server configuration item "persistpoolmax", then additional information will be shown:
Persistent pool size: 1
Persistent measured pool size: 1
Persistent pool max size: 10
Persistent max time (secs): 3660
The distinction between pool size and measured pool size is that the first is a counter that is updated when operations affect the persistent connections pool, whereas the measured size is the result of checking how many persistent connections are currently in the pool. It can be slightly different, since any expired connections are removed during the check.
Setting The State Of A Server
MariaDB MaxScale maintains a number of status flags for each server that is configured. These status flags are normally maintained by the monitors but there are two commands in the user interface that can be used to manually set these flags; the set server and clear server commands.
| Flag | Description |
|---|---|
| running | The server is responding to requests, accepting connections and executing database commands |
| master | The server is a master in a replication or it can be used for database writes |
| slave | The server is a replication slave or is considered as a read only database |
| synced | The server is a fully fledged member of a Galera cluster |
| maintenance | The server is in maintenance mode. It won't be used by services or monitored by monitors |
| stale | The server is a stale master server |
All status flags, with the exception of the maintenance flag, will be set by the monitors that are monitoring the server. If manual control is required the monitor should be stopped.
MaxScale> set server server3 maintenance MaxScale> clear server server3 maintenance MaxScale>
Viewing the persistent pool of DCB
The DCBs that are in the pool for a particular server can be displayed (in the format described below in the DCB section) with a command like:
MaxScale> show persistent server1 Number of persistent DCBs: 0
Working With Sessions
The MariaDB MaxScale session represents the state within MariaDB MaxScale. Sessions are dynamic entities and not named in the configuration file, this means that sessions can not be easily named within the user interface. The sessions are referenced using ID values, these are actually memory address, however the important thing is that no two session have the same ID.
What Sessions Are Active in MariaDB MaxScale?
There are a number of ways to find out what sessions are active, the most comprehensive being the list sessions command.
MaxScale> list sessions -----------------+-----------------+----------------+-------------------------- Session | Client | Service | State -----------------+-----------------+----------------+-------------------------- 10 | localhost | CLI | Session ready for routing 11 | ::ffff:127.0.0.1 | RWSplit | Session ready for routing -----------------+-----------------+----------------+-------------------------- MaxScale>
This will give a list of client connections.
Display Session Details
Once the session ID has been determined using one of the above method it is possible to determine more detail regarding a session by using the show session command.
MaxScale> show session 11
Session 11
State: Session ready for routing
Service: RWSplit
Client Address: maxuser@::ffff:127.0.0.1
Connected: Thu Apr 20 09:51:31 2017
Idle: 82 seconds
MaxScale>
Descriptor Control Blocks
The Descriptor Control Block or DCB is a very important entity within MariaDB MaxScale, it represents the state of each connection within MariaDB MaxScale. A DCB is allocated for every connection from a client, every network listener and every connection to a backend database. Statistics for each of these connections are maintained within these DCB’s.
As with session above the DCB’s are not named and are therefore referred to by the use of a unique ID, the memory address of the DCB.
Finding DCB’s
There are several ways to determine what DCB’s are active within a MariaDB MaxScale server, the most straightforward being the list dcbs command.
MaxScale> list dcbs Descriptor Control Blocks ------------------+----------------------------+--------------------+---------- DCB | State | Service | Remote ------------------+----------------------------+--------------------+---------- 0x68c0a0 | DCB for listening socket | RWSplit | 0x6e23f0 | DCB for listening socket | CLI | 0x691710 | DCB for listening socket | SchemaRouter | 0x7fffe40130f0 | DCB in the polling loop | CLI | localhost 0x6b7540 | DCB for listening socket | RWSplit-Hint | 0x6cd020 | DCB for listening socket | ReadConn | 0x7fffd80130f0 | DCB in the polling loop | RWSplit | ::ffff:127.0.0.1 0x7fffdc014590 | DCB in the polling loop | RWSplit | 0x7fffdc0148d0 | DCB in the polling loop | RWSplit | 0x7fffdc014c60 | DCB in the polling loop | RWSplit | 0x7fffdc014ff0 | DCB in the polling loop | RWSplit | ------------------+----------------------------+--------------------+---------- MaxScale>
A MariaDB MaxScale server that has activity on it will however have many more DCB’s than in the example above, making it hard to find the DCB that you require. The DCB ID is also included in a number of other command outputs, depending on the information you have it may be easier to use other methods to locate a particular DCB.
DCB Of A Client Connection
To find the DCB for a particular client connection it may be best to start with the list clients command and then look at each DCB for a particular client address to determine the one of interest.
DCB Details
The details of DCBs can be obtained by use of the show dcbs command
DCB: 0x68c0a0
DCB state: DCB for listening socket
Service: RWSplit
Role: Service Listener
Statistics:
No. of Reads: 0
No. of Writes: 0
No. of Buffered Writes: 0
No. of Accepts: 1
No. of High Water Events: 0
No. of Low Water Events: 0
DCB: 0x7fffd80130f0
DCB state: DCB in the polling loop
Service: RWSplit
Connected to: ::ffff:127.0.0.1
Username: maxuser
Role: Client Request Handler
Statistics:
No. of Reads: 5
No. of Writes: 0
No. of Buffered Writes: 6
No. of Accepts: 0
No. of High Water Events: 0
No. of Low Water Events: 0
DCB: 0x7fffdc014590
DCB state: DCB in the polling loop
Service: RWSplit
Server name/IP: 127.0.0.1
Port number: 3000
Protocol: MySQLBackend
Server status: Master, Running
Role: Backend Request Handler
Statistics:
No. of Reads: 4
No. of Writes: 0
No. of Buffered Writes: 3
No. of Accepts: 0
No. of High Water Events: 0
No. of Low Water Events: 0
The information Username, Protocol, Server Status are not always relevant, and will not be shown when they are null. The time the DCB was added to the persistent pool is only shown for a DCB that is in a persistent pool.
Working with Filters
Filters allow the request contents and result sets from a database to be modified for a client connection, pipelines of filters can be created between the client connection and MariaDB MaxScale router modules.
What Filters Are Configured?
Filters are configured in the configuration file for MariaDB MaxScale, they are given names and may be included in the definition of a service. The list filters command can be used to determine which filters are defined.
MaxScale> list filters Filters --------------------+-----------------+---------------------------------------- Filter | Module | Options --------------------+-----------------+---------------------------------------- counter | testfilter | QLA | qlafilter | /tmp/QueryLog Replicate | tee | QLA_BLR | qlafilter | /tmp/QueryLog.blr0 regex | regexfilter | MySQL5.1 | regexfilter | top10 | topfilter | --------------------+-----------------+---------------------------------------- MaxScale>
Retrieve Details Of A Filter Configuration
The command show filter can be used to display information related to a particular filter.
MaxScale> show filter QLA
Filter 0x719460 (QLA)
Module: qlafilter
Options: /tmp/QueryLog
Limit logging to connections from 127.0.0.1
Include queries that match select.*from.*user.*where
MaxScale>
Filter Usage
The show session command will include details for each of the filters in use within a session. First use list sessions or list clients to find the session of interest and then run the show session command
MaxScale> list sessions
-----------------+-----------------+----------------+--------------------------
Session | Client | Service | State
-----------------+-----------------+----------------+--------------------------
6 | ::ffff:127.0.0.1 | RWSplit-Top | Session ready for routing
7 | localhost | CLI | Session ready for routing
-----------------+-----------------+----------------+--------------------------
MaxScale> show session 6
Session 6
State: Session ready for routing
Service: RWSplit-Top
Client Address: maxuser@::ffff:127.0.0.1
Connected: Thu Apr 20 09:58:38 2017
Idle: 9 seconds
Filter: Top
Report size 10
Logging to file /tmp/top.1.
Current Top 10:
1 place:
Execution time: 0.000 seconds
SQL: show tables from information_schema
2 place:
Execution time: 0.000 seconds
SQL: show databases
3 place:
Execution time: 0.000 seconds
SQL: show tables
4 place:
Execution time: 0.000 seconds
SQL: select @@version_comment limit 1
The data displayed varies from filter to filter, the example above is the top filter. This filter prints a report of the current top queries at the time the show session command is run.
Working With Monitors
Monitors are used to monitor the state of databases within MariaDB MaxScale in order to supply information to other modules, specifically the routers within MariaDB MaxScale.
What Monitors Are Running?
To see what monitors are running within MariaDB MaxScale use the list monitors command.
MaxScale> list monitors ---------------------+--------------------- Monitor | Status ---------------------+--------------------- MySQL-Monitor | Running ---------------------+--------------------- MaxScale>
Details Of A Particular Monitor
To see the details of a particular monitor use the show monitor command.
MaxScale> show monitor MySQL-Monitor Monitor: 0x6577e0 Name: MySQL-Monitor State: Running Sampling interval: 10000 milliseconds Connect Timeout: 3 seconds Read Timeout: 1 seconds Write Timeout: 2 seconds Monitored servers: [127.0.0.1]:3000, [127.0.0.1]:3001, [127.0.0.1]:3002, [127.0.0.1]:3003 MaxScale MonitorId: 0 Replication lag: disabled Detect Stale Master: enabled Server information Server: server1 Server ID: 3000 Read only: OFF Slave configured: NO Slave IO running: NO Slave SQL running: NO Master ID: -1 Master binlog file: Master binlog position: 0 Server: server2 Server ID: 3001 Read only: OFF Slave configured: YES Slave IO running: YES Slave SQL running: YES Master ID: 3000 Master binlog file: binlog.000001 Master binlog position: 435 Server: server3 Server ID: 3002 Read only: OFF Slave configured: YES Slave IO running: YES Slave SQL running: YES Master ID: 3000 Master binlog file: binlog.000001 Master binlog position: 435 Server: server4 Server ID: 3003 Read only: OFF Slave configured: YES Slave IO running: YES Slave SQL running: YES Master ID: 3000 Master binlog file: binlog.000001 Master binlog position: 435 MaxScale>
Shutting Down A Monitor
A monitor may be shutdown using the shutdown monitor command. This allows for manual control of the status of servers using the set server and clear server commands.
MaxScale> shutdown monitor MySQL-Monitor MaxScale> list monitors ---------------------+--------------------- Monitor | Status ---------------------+--------------------- MySQL-Monitor | Stopped ---------------------+--------------------- MaxScale>
Restarting A Monitor
A monitor that has been shutdown may be restarted using the restart monitor command.
MaxScale> restart monitor MySQL-Monitor MaxScale> list monitors ---------------------+--------------------- Monitor | Status ---------------------+--------------------- MySQL-Monitor | Running ---------------------+--------------------- MaxScale>
MaxScale Status Commands
A number of commands exists that enable the internal MariaDB MaxScale status to be revealed, these commands give an insight to how MariaDB MaxScale is using resource internally and are used to allow the tuning process to take place.
MariaDB MaxScale Thread Usage
MariaDB MaxScale uses a number of threads, as defined in the MariaDB MaxScale configuration file, to execute the processing of requests received from clients and the handling of responses. The show threads command can be used to determine what each thread is currently being used for.
MaxScale> show threads Polling Threads. Historic Thread Load Average: 1.06. Current Thread Load Average: 0.00. 15 Minute Average: 0.10, 5 Minute Average: 0.30, 1 Minute Average: 0.67 Pending event queue length averages: 15 Minute Average: 0.00, 5 Minute Average: 0.00, 1 Minute Average: 0.00 ID | State | # fds | Descriptor | Running | Event ----+------------+--------+------------------+----------+--------------- 0 | Polling | | | | 1 | Polling | | | | 2 | Processing | 1 | 0x6e0dd0 | <202400ms | IN|OUT 3 | Polling | | | | MaxScale>
The resultant output returns data as to the average thread utilization for the past minutes 5 minutes and 15 minutes. It also gives a table, with a row per thread that shows what DCB that thread is currently processing events for, the events it is processing and how long, to the nearest 100ms has been send processing these events.
The Housekeeper Tasks
Internally MariaDB MaxScale has a housekeeper thread that is used to perform periodic tasks, it is possible to use the command show tasks to see what tasks are outstanding within the housekeeper.
MaxScale> show tasks Name | Type | Frequency | Next Due --------------------------+----------+-----------+------------------------- Load Average | Repeated | 10 | Thu Apr 20 10:02:26 2017 MaxScale>
Administration Commands
What Modules Are In use?
In order to determine what modules are in use, and the version and status of those modules the list modules command can be used.
MaxScale> list modules Modules. ----------------+-----------------+---------+-------+------------------------- Module Name | Module Type | Version | API | Status ----------------+-----------------+---------+-------+------------------------- qc_sqlite | QueryClassifier | V1.0.0 | 1.1.0 | Beta MySQLAuth | Authenticator | V1.1.0 | 1.1.0 | GA MySQLClient | Protocol | V1.1.0 | 1.1.0 | GA MaxAdminAuth | Authenticator | V2.1.0 | 1.1.0 | GA maxscaled | Protocol | V2.0.0 | 1.1.0 | GA MySQLBackendAuth| Authenticator | V1.0.0 | 1.1.0 | GA MySQLBackend | Protocol | V2.0.0 | 1.1.0 | GA mysqlmon | Monitor | V1.5.0 | 3.0.0 | GA schemarouter | Router | V1.0.0 | 2.0.0 | Beta readwritesplit | Router | V1.1.0 | 2.0.0 | GA topfilter | Filter | V1.0.1 | 2.2.0 | GA readconnroute | Router | V1.1.0 | 2.0.0 | GA cli | Router | V1.0.0 | 2.0.0 | GA ----------------+-----------------+---------+-------+------------------------- MaxScale>
This command provides important version information for the module. Each module has two versions; the version of the module itself and the version of the module API that it supports. Also included in the output is the status of the module, this may be "In Development", “Alpha”, “Beta”, “GA” or “Experimental”.
Enabling syslog and maxlog logging
MariaDB MaxScale can log messages to syslog, to a log file or to both. The approach can be set in the config file, but can also be changed from maxadmin. Syslog logging is identified by syslog and file logging by maxlog.
MaxScale> enable syslog MaxScale> disable maxlog
NOTE If you disable both, then you will see no messages at all.
Rotating the log file
MariaDB MaxScale logs messages to a log file in the log directory of MariaDB MaxScale. As the log file grows continuously, it is recommended to periodically rotate it. When rotated, the current log file will be closed and a new one with the same name opened.
To retain the earlier log entries, you need to first rename the log file and then instruct MaxScale to rotate it.
$ mv maxscale.log maxscale1.log $ # MaxScale continues to write to maxscale1.log $ kill -SIGUSR1 <maxscale-pid> $ # MaxScale closes the file (i.e. maxscale1.log) and reopens maxscale.log
There are two ways for rotating the log - flush log maxscale and flush logs; the result is identical. The two alternatives are due to historical reasons; earlier MariaDB MaxScale had several different log files.
MaxScale> flush log maxscale MaxScale> flush logs MaxScale>
Change MariaDB MaxScale Logging Options
From version 1.3 onwards, MariaDB MaxScale has a single log file where messages of various priority (aka severity) are logged. Consequently, you no longer enable or disable log files but log priorities. The priorities are the same as those of syslog and the ones that can be enabled or disabled are debug, info, notice and warning. Error and any more severe messages can not be disabled.
MaxScale> enable log-priority info MaxScale> disable log-priority notice MaxScale>
Please note that changes made via this interface will not persist across restarts of MariaDB MaxScale. To make a permanent change edit the maxscale.cnf file.
Adjusting the Log Throttling
From 2.0 onwards, MariaDB MaxScale will throttle messages that are logged too frequently, which typically is a sign that MaxScale encounters some error that just keeps on repeating. The aim is to prevent the log from flooding. The configuration specifies how many times a particular error may be logged during a period of a specified length, before it is suppressed for a period of a specified other length.
The current log throttling configuration can be queried with
MaxScale> show log_throttling 10 1000 100000
where the numbers are the count, the length (in milliseconds) of the period during which the counting is made, and the length (in milliseconds) of the period the message is subsequently suppressed.
The configuration can be set with
MaxScale> set log_throttling 10 1000 10000
where numbers are specified in the same order as in the show case. Setting any of the values to 0, disables the throttling.
Reloading The Configuration
A command, reload config, is available that will cause MariaDB MaxScale to reload the maxscale.cnf configuration file. Note that not all configuration changes are taken into effect when the configuration is reloaded. Refer to the Configuration Guide for a list of parameters that can be changed with it.
Shutting Down MariaDB MaxScale
The MariaDB MaxScale server may be shutdown using the shutdown maxscale command.
MaxScale> shutdown maxscale MaxScale>
Runtime Configuration Changes
Starting with the 2.1 version of MaxScale, you can modify the runtime configuration. This means that new objects (servers, listeners, monitors) can be created, altered and removed at runtime.
Servers
Creating a New Server
In order to add new servers into MaxScale, they must first be created. They can
be created with the create server command. Any runtime configuration changes
to servers are persisted meaning that they will still be in effect even after a
restart.
create server - Create a new server Usage: create server NAME HOST [PORT] [PROTOCOL] [AUTHENTICATOR] [OPTIONS] Parameters: NAME Server name HOST Server host address PORT Server port (default 3306) PROTOCOL Server protocol (default MySQLBackend) AUTHENTICATOR Authenticator module name (default MySQLAuth) OPTIONS Comma separated list of options for the authenticator The first two parameters are required, the others are optional. Example: create server my-db-1 192.168.0.102 3306
Adding Servers to Services and Monitors
To add a server to a service or a monitor, use the add server command. Any
changes to the servers of a service or a monitor are persisted meaning that they
will still be in effect even after a restart.
Servers added to services will only be taken into use by new sessions. Old sessions will only use the servers that were a part of the service when they were created.
add server - Add a new server to a service Usage: add server SERVER TARGET... Parameters: SERVER The server that is added to TARGET TARGET List of service and/or monitor names separated by spaces A server can be assigned to a maximum of 11 objects in one command Example: add server my-db my-service "Cluster Monitor"
Removing Servers from Services and Monitors
To remove servers from a service or a monitor, use the remove server
command. The same rules about server usage for services that apply to add
server also apply to remove server. The servers will only be removed from new
sessions created after the command is executed.
remove server - Remove a server from a service or a monitor Usage: remove server SERVER TARGET... Parameters: SERVER The server that is removed from TARGET TARGET List of service and/or monitor names separated by spaces A server can be removed from a maximum of 11 objects in one command Example: remove server my-db my-service "Cluster Monitor"
Altering Servers
You can alter server parameters with the alter server command. Any changes to
the address or port of the server will take effect for new connections
only. Changes to other parameters will take effect immediately.
Please note that in order for SSL to be enabled for a created server, all of the
required SSL parameters (ssl, ssl_key, ssl_cert and ssl_ca_cert) must be
given in the same command.
alter server - Alter server parameters Usage: alter server NAME KEY=VALUE ... Parameters: NAME Server name KEY=VALUE List of `key=value` pairs separated by spaces This will alter an existing parameter of a server. The accepted values for KEY are: address Server address port Server port monuser Monitor user for this server monpw Monitor password for this server ssl Enable SSL, value must be 'required' ssl_key Path to SSL private key ssl_cert Path to SSL certificate ssl_ca_cert Path to SSL CA certificate ssl_version SSL version ssl_cert_verify_depth Certificate verification depth To configure SSL for a newly created server, the 'ssl', 'ssl_cert', 'ssl_key' and 'ssl_ca_cert' parameters must be given at the same time. Example: alter server my-db-1 address=192.168.0.202 port=3307
Destroying Servers
You can destroy created servers with the destroy server command. Only servers
created with the create server command should be destroyed. A server can only
be destroyed once it has been removed from all services and monitors.
destroy server - Destroy a server Usage: destroy server NAME Parameters: NAME Server to destroy Example: destroy server my-db-1
Listeners
Creating New Listeners
To create a new listener for a service, use the create listener command. This
will create and start a new listener for a service which will immediately start
listening for new connections on the specified port.
Please note that in order for SSL to be enabled for a created listeners, all of
the required SSL parameters (ssl, ssl_key, ssl_cert and ssl_ca_cert)
must be given. All the create listener parameters do not need to be defined in
order for SSL to be enabled. The default parameter can be used to signal that
MaxScale should use a default value for the parameter in question.
create listener - Create a new listener for a service
Usage: create listener SERVICE NAME [HOST] [PORT] [PROTOCOL] [AUTHENTICATOR] [OPTIONS]
[SSL_KEY] [SSL_CERT] [SSL_CA] [SSL_VERSION] [SSL_VERIFY_DEPTH]
Parameters
SERVICE Service where this listener is added
NAME Listener name
HOST Listener host address (default [::])
PORT Listener port (default 3306)
PROTOCOL Listener protocol (default MySQLClient)
AUTHENTICATOR Authenticator module name (default MySQLAuth)
OPTIONS Options for the authenticator module
SSL_KEY Path to SSL private key
SSL_CERT Path to SSL certificate
SSL_CA Path to CA certificate
SSL_VERSION SSL version (default MAX)
SSL_VERIFY_DEPTH Certificate verification depth
The first two parameters are required, the others are optional.
Any of the optional parameters can also have the value 'default'
which will be replaced with the default value.
Example: create listener my-service my-new-listener 192.168.0.101 4006
Destroying Listeners
You can destroy created listeners with the destroy listener command. This will
remove the persisted configuration and it will not be created on the next
startup. The listener is stopped but it will remain a part of the runtime
configuration until the next restart.
destroy listener - Destroy a listener Usage: destroy listener SERVICE NAME Parameters: NAME Listener to destroy The listener is stopped and it will be removed on the next restart of MaxScale Example: destroy listener my-listener
Monitors
Creating New Monitors
The create monitor command creates a new monitor that is initially
stopped. Configure the monitor with the alter monitor command and then start
it with the restart monitor command. The user and password parameters of
the monitor must be defined before the monitor is started.
create monitor - Create a new monitor Usage: create monitor NAME MODULE Parameters: NAME Monitor name MODULE Monitor module Example: create monitor my-monitor mysqlmon
Altering Monitors
To alter a monitor, use the alter monitor command. Module specific parameters
can also be altered.
alter monitor - Alter monitor parameters Usage: alter monitor NAME KEY=VALUE ... Parameters: NAME Monitor name KEY=VALUE List of `key=value` pairs separated by spaces All monitors support the following values for KEY: user Username used when connecting to servers password Password used when connecting to servers monitor_interval Monitoring interval in milliseconds backend_connect_timeout Server coneection timeout in seconds backend_write_timeout Server write timeout in seconds backend_read_timeout Server read timeout in seconds This will alter an existing parameter of a monitor. To remove parameters, pass an empty value for a key e.g. 'maxadmin alter monitor my-monitor my-key=' Example: alter monitor my-monitor user=maxuser password=maxpwd
Destroying Monitors
To destroy a monitor, use the destroy monitor command. All servers need to be
removed from the monitor before it can be destroyed. Only created monitors
should be destroyed and they will remain a part of the runtime configuration
until the next restart.
destroy monitor - Destroy a monitor Usage: destroy monitor NAME Parameters: NAME Monitor to destroy The monitor is stopped and it will be removed on the next restart of MaxScale Example: destroy monitor my-monitor
Other Modules
Modules can implement custom commands called module commands. These are intended to allow modules to perform very specific tasks.
To list all module commands, execute list commands in maxadmin. This shows all
commands that the modules have exposed. It also explains what they do and what
sort of arguments they take.
list commands - List registered commands Usage: list commands [MODULE] [COMMAND] Parameters: MODULE Regular expressions for filtering module names COMMAND Regular expressions for filtering module command names Example: list commands my-module my-command
If no module commands are registered, no output will be generated. Refer to the module specific documentation for more details about module commands.
To call a module commands, execute call command <module> <command> in
maxadmin. The <module> is the name of the module and list commands.
call command - Call module command Usage: call command MODULE COMMAND ARGS... Parameters: MODULE The module name COMMAND The command to call ARGS... Arguments for the command To list all registered commands, run 'list commands'. Example: call command my-module my-command hello world!
An example of this is the dbfwfilter module that implements a rule reloading
mechanism as a module command. This command takes a filter name as a parameter.
maxadmin call command dbfwfilter rules/reload my-firewall-filter /home/user/rules.txt
Here the name of the filter is my-firewall-filter and the optional rule file
path is /home/user/rules.txt.
Tuning MariaDB MaxScale
The way that MariaDB MaxScale does its polling is that each of the polling threads, as defined by the threads parameter in the configuration file, will call epoll_wait to obtain the events that are to be processed. The events are then added to a queue for execution. Any thread can read from this queue, not just the thread that added the event.
Once the thread has done an epoll call with no timeout it will either do an epoll_wait call with a timeout or it will take an event from the queue if there is one. These two new parameters affect this behavior.
The first parameter, which may be set by using the non_blocking_polls option in the configuration file, controls the number of epoll_wait calls that will be issued without a timeout before MariaDB MaxScale will make a call with a timeout value. The advantage of performing a call without a timeout is that the kernel treats this case as different and will not rescheduled the process in this case. If a timeout is passed then the system call will cause the MariaDB MaxScale thread to be put back in the scheduling queue and may result in lost CPU time to MariaDB MaxScale. Setting the value of this parameter too high will cause MariaDB MaxScale to consume a lot of CPU when there is infrequent work to be done. The default value of this parameter is 3.
This parameter may also be set via the maxadmin client using the command set nbpolls <number>.
The second parameter is the maximum sleep value that MariaDB MaxScale will pass to epoll_wait. What normally happens is that MariaDB MaxScale will do an epoll_wait call with a sleep value that is 10% of the maximum, each time the returns and there is no more work to be done MariaDB MaxScale will increase this percentage by 10%. This will continue until the maximum value is reached or until there is some work to be done. Once the thread finds some work to be done it will reset the sleep time it uses to 10% of the maximum.
The maximum sleep time is set in milliseconds and can be placed in the [maxscale] section of the configuration file with the poll_sleep parameter. Alternatively it may be set in the maxadmin client using the command set pollsleep <number>. The default value of this parameter is 1000.
Setting this value too high means that if a thread collects a large number of events and adds to the event queue, the other threads might not return from the epoll_wait calls they are running for some time resulting in less overall performance. Setting the sleep time too low will cause MariaDB MaxScale to wake up too often and consume CPU time when there is no work to be done.
The show epoll command can be used to see how often we actually poll with a timeout, the first two values output are significant. Also the "Number of wake with pending events" is a good measure. This is the count of the number of times a blocking call returned to find there was some work waiting from another thread. If the value is increasing rapidly reducing the maximum sleep value and increasing the number of non-blocking polls should help the situation.
MaxScale> show epoll
Poll Statistics.
No. of epoll cycles: 343
No. of epoll cycles with wait: 66
No. of epoll calls returning events: 19
No. of non-blocking calls returning events: 10
No. of read events: 2
No. of write events: 15
No. of error events: 0
No. of hangup events: 0
No. of accept events: 4
No. of times no threads polling: 4
Total event queue length: 1
Average event queue length: 1
Maximum event queue length: 1
No of poll completions with descriptors
No. of descriptors No. of poll completions.
1 19
2 0
3 0
4 0
5 0
6 0
7 0
8 0
9 0
>= 10 0
MaxScale>
If the "Number of DCBs with pending events" grows rapidly it is an indication that MariaDB MaxScale needs more threads to be able to keep up with the load it is under.
The show threads command can be used to see the historic average for the pending events queue, it gives 15 minute, 5 minute and 1 minute averages. The load average it displays is the event count per poll cycle data. An idea load is 1, in this case MariaDB MaxScale threads and fully occupied but nothing is waiting for threads to become available for processing.
The show eventstats command can be used to see statistics about how long events have been queued before processing takes place and also how long the events took to execute once they have been allocated a thread to run on.
MaxScale> show eventstats
Event statistics.
Maximum queue time: 000ms
Maximum execution time: 000ms
Maximum event queue length: 1
Total event queue length: 4
Average event queue length: 1
| Number of events
Duration | Queued | Executed
---------------+------------+-----------
< 100ms | 27 | 26
100 - 200ms | 0 | 0
200 - 300ms | 0 | 0
300 - 400ms | 0 | 0
400 - 500ms | 0 | 0
500 - 600ms | 0 | 0
600 - 700ms | 0 | 0
700 - 800ms | 0 | 0
800 - 900ms | 0 | 0
900 - 1000ms | 0 | 0
1000 - 1100ms | 0 | 0
1100 - 1200ms | 0 | 0
1200 - 1300ms | 0 | 0
1300 - 1400ms | 0 | 0
1400 - 1500ms | 0 | 0
1500 - 1600ms | 0 | 0
1600 - 1700ms | 0 | 0
1700 - 1800ms | 0 | 0
1800 - 1900ms | 0 | 0
1900 - 2000ms | 0 | 0
2000 - 2100ms | 0 | 0
2100 - 2200ms | 0 | 0
2200 - 2300ms | 0 | 0
2300 - 2400ms | 0 | 0
2400 - 2500ms | 0 | 0
2500 - 2600ms | 0 | 0
2600 - 2700ms | 0 | 0
2700 - 2800ms | 0 | 0
2800 - 2900ms | 0 | 0
2900 - 3000ms | 0 | 0
> 3000ms | 0 | 0
MaxScale>
The statics are defined in 100ms buckets, with the count of the events that fell into that bucket being recorded.
