simple-repctl is a utility to configure, reconfigure, start, stop, crash, generate workloads, dump, restore, benchmark, and monitor a set of MySQL servers for development environments where all the MySQL instances run on a single computer. Replication relationships can be set up among the instances with a single command. While running a load generator or benchmark, the replication status, including current lag, can be seen in a continuously updated display. A slave can be added to an existing server that already has data.
simple-repctl is written in Ruby as a Thor script. It can be viewed as a specialized version of Guiseppe Maxia’s MySQL Sandbox (launchpad.net/mysql-sandbox), but it is derived from a more sophisticated version of a repctl tool that works across multiple virtual machine instances in a cloud computing environment.
tethys:repctl mbs$ thor list mysql ----- thor mysql:change_master MASTER SLAVE FILE POSITION # Execute CHANGE MASTER TO on the SLAVE. thor mysql:cluster_user INSTANCE # Create the cluster user account on a MySQL instance. thor mysql:config INSTANCE # Initialize the data directory for a new instance. thor mysql:config_all # Initialize the data directories for all instances. thor mysql:crash INSTANCE # Crash a running MySQL server. thor mysql:dump INSTANCE [DUMPFILE] # Dump all databases after FLUSH TABLES WITH READ LOCK thor mysql:repl_user INSTANCE # Create the replication user account on a MySQL insta... thor mysql:reset INSTANCE # Remove database and restart MySQL server. thor mysql:reset_all # Remove all databases and restart MySQL instances. thor mysql:restore INSTANCE [DUMPFILE] # Restore INSTANCE from a 'mysqldump' file DUMPFILE. thor mysql:start_slave SLAVE # Issue START SLAVE on the SLAVE MySQL instance. thor mysql:status # Show the status of replication. thor mysql:stop INSTANCE # Stop a running MySQL server instance. thor mysql:stop_all # Stop all the MySQL servers. setup ----- thor setup:add_slave MASTER SLAVE # Master has some data that is used to initialize the slave. thor setup:repl_pair MASTER SLAVE # Set up a single master/slave replication pair from the very beginning. utils ----- thor utils:bench [INSTANCE] [PROPS] # Run the Tungsten Bristlecone benchmarker. The INSTAN... thor utils:create_db [INSTANCE] [DBNAME] # "Create a database on a MySQL instance. INSTANCE de... thor utils:create_tbl [INSTANCE] [DBNAME] [TBLNAME] # Create a database table. INSTANCE defaults to DEFAU... thor utils:gen_rows [INSTANCE], [DBNAME], [TBLNAME] # Add rows to a table that was created by "utils:crea...
This tool needs some configuration before you can use it.
You should have an valid MySQL installation and the Thor gem installed. Your existing MySQL server will not be affected by the repctl script. However, binaries from this installation will be reused. In the config.rb file set the constants:
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MYSQL_HOME – the location of the local MySQL installation
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DATA_HOME – the location of the directory where per-MySQL server data directories are created.
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DUMP_DIR – the location where you want dump files to be stored
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RELAY_LOG – adjust this according to your hostname
Next, define the potential instances you want to create. Edit the servers.yml file as appropriate.
Finally, edit the existing my*.cnf* files to at least have the correct datadir defined.
You are now ready to rock. Run thor mysql:start_all to start up all the servers listed in your servers.yml file. Instead or subsequently, you can run thor setup:repl_pair 1 2 to reset everything and create a master/slave replication pair. Start up some load to the MySQL master (at socket /tmp/mysql1.sock, by default), then watch the replication status change by running thor mysql:status -s 1 2 -c 5 to see a continuous update of the status, updated every 5 seconds. Add a new slave using instance 3, which may or may not be running and may or may not have its data directory initialized, by running thor setup:add_slave 1 3. This does a dump on the master and a restore on the slave and restarts replication using the proper replication coordinates.