Patroni cluster management commands =================================== You can use Patroni as a single-master failover manager with the M1 architecture using the following command options: .. code:: shell tpaexec configure cluster_name -a M1 --enable-patroni --postgresql 14 You can also use Patroni as a failover manager by setting the following ``config.yml`` option: .. code:: yaml cluster_vars: failover_manager: patroni If deploying to RedHat, you must also add the ``PGDG`` repository to your yum repository list in ``config.yml`` : .. code:: yaml cluster_vars: yum_repository_list: - PGDG TPA ``configure`` adds 3 etcd nodes and 2 haproxy nodes. Etcd is used for the Distributed Configuration Store (DCS). Patroni supports other DCS backends, but they aren’t currently supported by EDB or TPA. TPA uses Patroni’s feature of converting an existing PostgreSQL standalone server. This mechanism allows for TPA to initialize and manage configuration. Once a single PostgreSQL server and database is created, Patroni creates replicas and configures replication. TPA then removes any Postgres configuration files used during setup. Once this is set up, you can continue to manage Postgres using TPA and settings in ``config.yml`` for the cluster. You can also use Patroni interfaces, such as the command line ``patronictl`` and the REST API, but we recommend using TPA methods wherever possible. Configuration options --------------------- You can use these configuration variables to control certain behaviors when deploying Patroni in TPA. .. csv-table:: :header: Variable,Default value,Description :widths: 12,12,18 :align: left :class: longtable `patroni_super_user`,postgres,User to create in Postgres for superuser role. `patroni_replication_user`,replicator,Username to create in Postgres for replication role. `patroni_restapi_user`,patroni,Username to configure for the Patroni REST API. `patroni_rewind_user`,rewind,Username to create in postgres for pg_rewind function. `patroni_installation_method`,pkg,"Install Patroni from packages or source (for example, Git repo or local source directory if Docker)." `patroni_ssl_enabled`,no,Whether to enable SSL for REST API and ctl connection. Uses the cluster SSL cert and CA if available. `patroni_rewind_enabled`,yes,Whether to enable Postgres rewind; creates a user defined by patroni_rewind_user and adds config section. `patroni_watchdog_enabled`,no,Whether to configure the kernel watchdog for additional split-brain prevention. `patroni_dcs`,etcd,"The backend to use for the DCS. Currently, the only option is etcd." `patroni_listen_port`,8008,REST API TCP port number. `patroni_conf_settings`,{},A structured data object with overrides for Patroni configuration. Partial data can be provided and will be merged with the generated config. Be careful to not override values that are generated based on instance information known at runtime. `patroni_dynamic_conf_settings`,{},Optional structured data just for DCS settings. This will be merged onto `patroni_conf_settings`. `patroni_repl_max_lag`,None,This is used in the haproxy backend health check only when `haproxy_read_only_load_balancer_enabled` is true. See :ref:`Configuring lvm-direct for production ` for possible values for `/replica?lag`. Patroni configuration file settings ----------------------------------- Configuration for Patroni is built from three layers, starting with defaults set by the Patroni daemon, config loaded from the DCS, and finally from local configuration. The last can be controlled from either configuration file and overrides by way of the environment. TPA controls the configuration file, and values are built up in this order. DCS config to be sent to the API and stored in the bootstrap section of the config file: - TPA vars for ``postgres`` are loaded into the DCS settings. See :ref:`postgresql.conf.md ` . Some features aren’t supported. See notes that follow. - Patroni defaults for DCS settings. - User-supplied defaults in ``patroni_dynamic_conf_settings`` . If you want to override any DCS settings, you can do that here. Local config stored in the YAML configuration file: - ``bootstrap.dcs`` loaded from previous steps. - Configuration enabled by feature flags, such as ``patroni_ssl_enabled`` . See the table in :ref:`Overview of configuration options ` . - Then, finally, overloaded from user-supplied settings, the ``patroni_conf_settings`` option. If you want to change or add a configuration not controlled by a feature flag, then this is the best place to do it. Configuration is merged on top of the configuration generated by TPA from cluster information, such as IP addresses, port numbers, cluster roles, and so on. Use caution in what you override, as this might affect the stable operation of the cluster. As Patroni stores all Postgres configuration in the DCS and controls how and when this is distributed to Postgres, some features of TPA are incompatible with Patroni: - You can’t change the template used to generate ``postgresql.conf`` with the setting ``postgres_conf_template`` . - You can’t change the location of Postgres config files with the setting ``postgres_conf_dir`` . Patroni configuration in TPA ``config.yml`` ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ You can override single values: .. code:: yaml cluster_vars: patroni_conf_settings: bootstrap: dcs: ttl: 120 You can also override full blocks (with an example from Patroni documentation): .. code:: yaml cluster_vars: patroni_conf_settings: restapi: http_extra_headers: X-Frame-Options: SAMEORIGIN X-XSS-Protection: 1; mode=block X-Content-Type-Options: nosniff https_extra_headers: Strict-Transport-Security: max-age=31536000; includeSubDomains If you want to negate a value or section that’s present in the default TPA config vars, you can set the value to ``null`` . This causes Patroni to ignore this section when loading the config file. For example, the default TPA config for ``log`` is: .. code:: yaml log: dir: /var/log/patroni To turn off logging, add this to ``config.yml`` : .. code:: yaml cluster_vars: patroni_conf_settings: log: null TPA provides this minimal set of tools for managing Patroni clusters. Status ------ To see the current status of the TPA cluster according to Patroni, run: .. code:: shell tpaexec status cluster_name Switchover ---------- To perform a switchover to a replica node (for example, to perform maintenance) run: .. code:: shell tpaexec switchover cluster_name The ``new_primary`` argument must be the name of an existing cluster node that’s currently running as a healthy replica. Checks are performed to ensure this is true before a switchover is performed. Once a switchover has been performed, we recommend that you run ``deploy`` and ``test`` to ensure a healthy cluster: .. code:: shell tpaexec deploy cluster_name tpaexec test cluster_name TPA detects the current role of nodes during deploy regardless of what ``config.yml`` contains, for example, if a different node is the leader.