MySQL Variables and Parameters

This article summarizes the variables that are most frequently changed and most likely to affect results in the public mysql_ansible entry playbooks, so you can quickly locate the right configuration entry before deployment, backup, restore, and monitoring integration.

1. General variables

File: playbooks/common_config.yml

Variable	Default value	Function
`mysql_version`	`8.4.8`	MySQL version. Current public capabilities mainly target `5.7`, `8.0`, and `8.4`
`mysql_port`	`3306`	Instance port and the baseline for several derived paths and service names
`server_specs`	`auto`	Server sizing. You can keep auto-detection or set a fixed value such as `4c8g`
`db_type`	`mysql`	Database type. Supports `mysql`, `percona`, and `greatsql`
`mysql_packages_dir`	`../downloads/`	Directory for MySQL installation packages
`mysql_user` / `mysql_group`	`mysql` / `mysql`	Linux runtime user and group for MySQL
`mysql_data_dir_base`	`/database/{{ db_type }}`	Base directory for MySQL data, logs, and configuration
`mysql_service_name`	`mysql{{ mysql_port }}`	systemd service name, derived from the MySQL port by default
`mysql_admin_user` / `mysql_admin_password`	`admin` / `Dbbot_admin@8888`	Administrative account and password
`mysql_rple_user` / `mysql_rple_password`	`repl` / `Dbbot_repl@8888`	Replication account and password
`mysql_backup_user` / `mysql_backup_password`	`backup` / `Dbbot_backup@8888`	Backup account and password
`mysql_monitor_user` / `mysql_monitor_password`	`monitor` / `Dbbot_monitor@8888`	Monitoring account used by `mysqld_exporter`
`mysql_cluster_admin_user` / `mysql_cluster_admin_password`	`clusteradmin` / `Dbbot_clusteradmin@8888`	mysqlshell management account for InnoDB Cluster
`mysql_router_user` / `mysql_router_password`	`mysqlrouter` / `Dbbot_mysqlrouter@8888`	Account used by MySQL Router to read metadata
`mysql_character_set_server`	`utf8mb4`	Server character set
`mysql_transaction_isolation`	`READ-COMMITTED`	Default transaction isolation level
`mysql_default_time_zone`	`+8:00`	Default MySQL time zone
`mysql_max_connections`	`1000`	Maximum number of connections
`mysql_binlog_format`	`row`	Binlog format. This is especially important for MGR and InnoDB Cluster
`fcs_auto_download_packages`	`true`	Whether the control node automatically downloads MySQL, Shell, Router, and Exporter packages
`fcs_allow_dbbot_default_passwd`	`false`	Whether execution is allowed to continue with dbbot public default passwords
`fcs_create_mysql_fast_login`	`true`	Whether to create shortcuts such as `db3306` for the `mysql` user
`fcs_backup_script_create_backup_user`	`true`	Whether the backup playbook creates the backup account automatically
`fcs_role_mysqld_exporter_create_monitor_user`	`true`	Whether `mysqld_exporter` installation creates the monitor account automatically
`fcs_mysql_use_jemalloc`	`false`	Whether to explicitly enable `jemalloc` preload
`fcs_mysql_allow_bundled_jemalloc_fallback`	`false`	Whether dbbot is allowed to fall back to the bundled legacy RPM when the OS repo has no `jemalloc`
`fcs_use_greatsql_ha`	`true`	Whether GreatSQL HA related capabilities are enabled
`dbbot_confirmation_input`	`""`	In automation you can set this to `confirm`; for manual runs, keeping it empty is safer

Notes:

Public default passwords follow the Dbbot_<user>@8888 / Dbbot_<linux_user>@9999 convention. By default, fcs_allow_dbbot_default_passwd: false, so playbooks block those defaults in pre_tasks.
The current default for fcs_mysql_use_jemalloc is false, which means the system allocator remains the default behavior.
When fcs_mysql_use_jemalloc: true, dbbot first tries the OS repository package. It only falls back to the bundled legacy RPM if you explicitly set fcs_mysql_allow_bundled_jemalloc_fallback: true.
mysql_binlog_format is configurable in the common file, but mgr.yml still requires row.

2. Directory and package variables

File: playbooks/advanced_config.yml

Variable	Default value	Function
`mycnf_dir`	`{{ mysql_data_dir_base }}/{{ mysql_port }}/etc`	Directory that stores `my.cnf`
`datadir`	`{{ mysql_data_dir_base }}/{{ mysql_port }}/data`	Data directory
`tmpdir`	`{{ mysql_data_dir_base }}/{{ mysql_port }}/tmp`	Temporary directory
`binlog_dir` / `relaylog_dir`	`{{ mysql_data_dir_base }}/{{ mysql_port }}/log`	Directories for binlog and relay log files
`redolog_dir`	`{{ datadir }}`	Redo log directory, which defaults back to `datadir`
`socket` / `mysqlx_socket`	Derived from `datadir`	MySQL and MySQL X socket paths
`mysql_linux_glibc_tag`	Auto-calculated by version and OS	glibc tag used in the MySQL package name
`mysql_linux_archive_suffix`	Auto-calculated by version and OS	Archive suffix used in the MySQL package name
`mysql_package`	Derived from the variables above	Final MySQL package file name expected by the playbook

Recommendations:

Only change these variables when you need a custom directory layout, custom offline package naming, or a special restore path.
The cleanup scope of unsafe_uninstall.yml also depends on these directory variables. With the current default layout, it removes both the instance data and log directories.

3. Primary-replica and MHA variables

Files:

playbooks/vars/var_master_slave.yml
playbooks/vars/var_mha.yml

Variable	Default value	Function
`master_ip`	`192.0.2.131`	Primary server IP
`slave_ips`	`['192.0.2.132', '192.0.2.133']`	Replica IP list
`sub_nets`	`1%`	Trusted subnet, domain, or IP range for MySQL
`manager_ip`	`192.0.2.133`	Node used by the MHA manager
`net_work_interface`	`ens33`	NIC used to bind the MHA VIP
`vip`	`192.0.2.130`	MHA VIP
`vip_netmask`	`32`	MHA VIP netmask

Notes:

master_ip and slave_ips must match the hosts in the inventory.
manager_ip must not be the same as master_ip; it is usually placed on a replica node.
The actual variable name is slave_ips, not replica_ips.

4. MGR variables

File: playbooks/vars/var_mgr.yml

Variable	Default value	Function
`mysql_binlog_format`	`row`	Overrides the common setting so MGR uses `row`
`mysql_mgr_port`	Auto-calculated, for example `33061` when `mysql_port=3306`	Group Replication communication port
`mysql_mgr_hosts`	`['192.0.2.131', '192.0.2.132', '192.0.2.133']`	List of MGR members
`sub_nets`	`1%`	Trusted source range
`greatsql_vip`	`192.0.2.134`	VIP for GreatSQL HA scenarios
`greatsql_net_work_interface`	`ens33`	NIC used by the GreatSQL HA VIP
`greatsql_netmask`	`255.255.255.255`	Netmask used by GreatSQL HA
`greatsql_group_replication_arbitrator`	`false`	Whether to enable an arbitrator node
`greatsql_group_replication_arbitrator_hosts`	`['192.0.2.133']`	Arbitrator node list

Notes:

greatsql_* variables only apply when db_type: greatsql.
mgr.yml deploys single-primary mode by default.

5. InnoDB Cluster and Router variables

Files:

playbooks/vars/var_innodb_cluster.yml
playbooks/vars/var_innodb_cluster_router.yml

InnoDB Cluster variables:

Variable	Default value	Function
`innodb_cluster_name`	`myCluster{{ mysql_port }}`	Cluster name
`innodb_cluster_primary`	`192.0.2.131`	Initial primary node
`innodb_cluster_members`	`['192.0.2.131', '192.0.2.132', '192.0.2.133']`	Cluster member list
`mysql_mgr_port`	Auto-calculated, for example `33061` when `mysql_port=3306`	InnoDB Cluster still relies on the underlying MGR port
`mysql_mgr_hosts`	`{{ innodb_cluster_members }}`	Underlying MGR member list
`mysql_cluster_admin_user` / `mysql_cluster_admin_password`	`clusteradmin` / `Dbbot_clusteradmin@8888`	mysqlshell management account

Router variables:

Variable	Default value	Function
`router_enable_ha`	`true`	Whether Router HA is enabled with keepalived
`router_bootstrap_server`	`192.0.2.131`	Cluster node used for Router bootstrap
`router_vip`	`198.51.100.150`	Router HA VIP
`router_net_work_interface`	`ens33`	NIC used by the VIP
`router_ha_nodes`	Two-node example	Router HA nodes, roles, and priorities
`router_vip_netmask`	`32`	Router VIP netmask
`router_ports`	`rw/ro/http...` dictionary	Router ports, enable flags, and health-check participation
`max_total_connections`	`1000`	Global Router connection limit
`router_rest_api_bind_address`	`127.0.0.1`	REST API bind address
`router_rest_api_auth_mode`	`file`	REST API authentication mode
`router_rest_api_file_user` / `router_rest_api_file_password`	`router_api_user` / `Dbbot_router_api_user@8888`	File-based REST API credentials

Notes:

router_ha_nodes only matters when router_enable_ha: true.
By default, router_ports.http.port is 8443, and mysqlrouter_exporter reads Router metrics from this REST API endpoint.

6. Exporter variables

Files:

playbooks/vars/var_exporter_install.yml
playbooks/vars/var_router_exporter_install.yml

Variable	Default value	Function
`node_exporter_install`	`true`	Whether to install `node_exporter`
`node_exporter_port`	`9100`	Listening port for `node_exporter`
`node_exporter_install_type`	`dbbot`	Installation mode: `dbbot`, `pmm`, or `package`
`mysqld_exporter_install`	`true`	Whether to install `mysqld_exporter`
`mysqld_exporter_topology`	`ms`	Topology type: `ms` or `mgr`
`mysqld_exporter_port`	`auto`	Exporter port. Can be auto-calculated or explicitly set
`mysqld_exporter_port_auto_base`	`9104`	Start of the auto-generated exporter port range
`mysqld_exporter_port_auto_mysql_base`	`3306`	MySQL baseline port used in the auto port calculation
`mysqld_exporter_install_type`	`dbbot`	Installation mode: `dbbot`, `pmm`, or `package`
`mysqlrouter_exporter_install`	`true`	Whether to install `mysqlrouter_exporter`
`mysqlrouter_exporter_port`	`9165`	Listening port for `mysqlrouter_exporter`
`mysqlrouter_exporter_api_base_url`	`https://127.0.0.1:8443/api/20190715`	Router REST API endpoint
`mysqlrouter_exporter_api_user` / `mysqlrouter_exporter_api_password`	`router_api_user` / `Dbbot_router_api_user@8888`	Router API credentials
`mysqlrouter_exporter_insecure_skip_verify`	`true`	Whether to skip HTTPS certificate verification

Auto port rule:

When mysqld_exporter_port: auto, the port is calculated as 9104 + mysql_port - 3306.
mysqlrouter_exporter depends on the Router REST API by default, so if you change the Router HTTP port or bind address, update the exporter settings as well.

7. MySQL 8.4 clone backup variables

File: playbooks/vars/var_backup_script_8.4.yml

Variable	Default value	Function
`backup_topology`	`auto`	Topology detection mode. Supports `auto`, `ms`, `mgr`, `mic`, and `single`
`backup_scope`	`primary_only`	Backup target scope. Supports `primary_only`, `replica_one`, `replica_all`, `all`, and `selected`
`backup_preferred_host`	`""`	Required when `backup_scope=selected`
`backup_base_dir`	`/backup`	Base backup directory
`backup_script_dir`	`{{ mysql_data_dir_base }}/scripts`	Directory that stores backup scripts
`backup_script_path`	`{{ backup_script_dir }}/backup_clone{{ mysql_port }}.sh`	Clone backup script path
`backup_schedule_script_path`	`{{ backup_script_dir }}/backup_schedule{{ mysql_port }}.sh`	Scheduler script path
`backup_purge_script_path`	`{{ backup_script_dir }}/backup_purge{{ mysql_port }}.sh`	Purge script path
`backup_config_path`	`{{ backup_script_dir }}/backup_clone{{ mysql_port }}.conf`	Backup configuration file path
`backup_keep_full`	`2`	Number of full snapshots to retain
`backup_keep_binlog_days`	`7`	Number of days to retain binlogs
`backup_cron`	`0 2 * * *`	Cron expression used by the scheduled backup

Notes:

When backup_scope=selected, backup_preferred_host must be set explicitly.
backup_cron is validated as a five-field cron expression in pre_tasks.

8. MySQL 8.4 PITR restore variables

File: playbooks/vars/var_restore_pitr_8.4.yml

Variable	Default value	Function
`restore_mode`	`new_instance`	Restore mode: `new_instance` or `existing_instance`
`backup_snapshot_id`	`""`	Backup snapshot identifier. Required
`backup_source_mysql_port`	`3306`	Source MySQL port used by the backup
`restore_target_mysql_port`	`3388`	Target MySQL port for the restored instance
`backup_root_dir`	`/backup`	Base backup directory on the restore host
`backup_dir`	`{{ backup_root_dir }}/mysql{{ backup_source_mysql_port }}/{{ backup_snapshot_id }}`	Resolved backup directory
`enable_pitr`	`true`	Whether to apply binlogs after the clone restore
`pitr_target_time`	`""`	Stop point based on wall-clock time, format `YYYY-MM-DD HH:MM:SS`
`pitr_target_gtid`	`""`	Stop point based on a single GTID, format `uuid:seq`
`pitr_target_gtid_inclusive`	`false`	Whether the target GTID itself is included
`restore_mysql_host` / `restore_mysql_user` / `restore_mysql_password`	`127.0.0.1` / `{{ mysql_admin_user }}` / `{{ mysql_admin_127_password }}`	Connection settings used when replaying binlogs
`restore_allow_nonempty_datadir`	`false`	Whether restore is allowed when the target datadir already contains data
`restore_mysql_start_timeout`	`300`	Timeout in seconds when waiting for MySQL to start
`mysql_port`	`{{ restore_target_mysql_port }}`	Keeps the restore flow aligned with the target MySQL port

Restore constraints:

When enable_pitr: true, set exactly one of pitr_target_time or pitr_target_gtid.
restore_pitr_8.4.yml only supports db_type: mysql and mysql_version: 8.4.x.

9. Notes for the 5.7 backup script and uninstall

backup_script.yml and unsafe_uninstall.yml do not have dedicated vars/*.yml files. They mainly depend on the following configuration sources:

The MySQL 5.7 backup script relies on common_config.yml and advanced_config.yml
Whether the backup user is created automatically is controlled by fcs_backup_script_create_backup_user
The delete scope of unsafe_uninstall.yml follows datadir, tmpdir, binlog_dir, relaylog_dir, and redolog_dir from advanced_config.yml

Additional notes:

backup_script.yml is currently for MySQL 5.7, and its retention behavior is mainly defined inside the role template rather than a public variable file.
unsafe_uninstall.yml keeps the software base directory, Linux user, and my.cnf, but its delete scope still follows advanced_config.yml. With the current default layout, it removes both the instance data and log directories. It still requires manual confirmation before execution.

MySQL Variables and Parameters

1. General variables

2. Directory and package variables

3. Primary-replica and MHA variables

4. MGR variables

5. InnoDB Cluster and Router variables

6. Exporter variables

7. MySQL 8.4 clone backup variables

8. MySQL 8.4 PITR restore variables

9. Notes for the 5.7 backup script and uninstall

10. Recommended reading order