Updating configuration of YDB clusters deployed with Ansible
During initial deployment, the Ansible playbook used the provided config file to create the initial cluster configuration. Technically, it generates two variants of the original config file and deploys them to all hosts via Ansible's mechanism for cross-server file copy. This article explains which options are available to change the cluster's configuration after the initial deployment.
Update configuration via Ansible playbook
ydb-ansible repository contains a playbook called ydb_platform.ydb.update_config that can be used to update YDB cluster's configuration. Go to the same directory used for the initial deployment, edit files/config.yaml as needed, and then run this playbook:
ansible-playbook ydb_platform.ydb.update_config
The playbook deploys the new version of the config files and then performs a rolling restart.
Filter by node type
Tasks in the ydb_platform.ydb.update_config playbook are tagged with node types, so you can use Ansible's tags functionality to filter nodes by their kind.
These two commands are equivalent and will change the configuration of all storage nodes:
ansible-playbook ydb_platform.ydb.update_config --tags storage
ansible-playbook ydb_platform.ydb.update_config --tags static
These two commands are equivalent and will change the configuration of all database nodes:
ansible-playbook ydb_platform.ydb.update_config --tags database
ansible-playbook ydb_platform.ydb.update_config --tags dynamic
Skip restart
There's a no_restart tag to only deploy the config files and skip the cluster restart. This might be useful if the cluster will be restarted later manually or as part of some other maintenance tasks. Example:
ansible-playbook ydb_platform.ydb.update_config --tags no_restart
Dynamic configuration
YDB has its own configuration management mechanism called dynamic configuration. It is agnostic of the chosen cluster deployment method and allows for flexible cluster configuration even in multitenant environments.
Consider switching to dynamic configuration if manually deploying config files and doing a complete rolling restart on any change is no longer feasible.