Deploying Multiple MySQL Instances with MySQL Shell DBA Component

The author, a senior database expert, continues the tutorial on MySQL Shell's DBA component, showing how to extend its usage for custom MySQL instance deployment.

1. Deploying multiple MySQL versions: By default the DBA component picks the mysqld found in the current $PATH , which on the author's machine is MySQL 8.0. Using dba.deploy_sandbox_instance(3350) creates a sandbox on port 3350 with version 8.0.29. To deploy a different version, add the desired MySQL binary directory to the front of $PATH (e.g., export PATH=/root/opt/mysql/5.7.34/bin:$PATH ) and then run the same command on a new port (3351) to get a 5.7.34 instance.

2. Changing the base directory of deployments: By default instances are created under ~/mysql-sandboxes with a sub‑directory named after the port. Two methods are provided:

Specify sandboxDir when calling dba.deploy_sandbox_instance , e.g., dba.deploy_sandbox_instance(3352, {"sandboxDir":"/tmp/mysql-sandbox"}) .

Set the global option --persist sandboxDir /tmp/mysql-sandbox in the Shell component, which applies to all subsequent deployments.

After setting the global option, a loop such as for i in range(3353,3355): dba.deploy_sandbox_instance(i) creates instances 3353 and 3354 under /tmp/mysql-sandbox .

3. Modifying instance parameters: Parameters can be set at deployment time by passing a mysqldOptions array, e.g., dba.deploy_sandbox_instance(3355, {"mysqldOptions":["server_id=1000","tmp_table_size=64M","read_buffer_size=1M"]}) . The resulting my.cnf can be verified with grep "server_id\|tmp_table_size\|read_buffer_size" my.cnf . For bulk changes, edit my.cnf directly and restart the instance.

Summary: MySQL Shell's DBA component provides a convenient way to spin up sandbox MySQL instances for testing or development, but it is not recommended for production use because the instances are easily mutable from the Shell, increasing operational risk.