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diff --git a/nixos/modules/services/databases/postgresql.md b/nixos/modules/services/databases/postgresql.md new file mode 100644 index 000000000000..1805bafe3be3 --- /dev/null +++ b/nixos/modules/services/databases/postgresql.md @@ -0,0 +1,173 @@ +# PostgreSQL {#module-postgresql} + +<!-- FIXME: render nicely --> +<!-- FIXME: source can be added automatically --> + +*Source:* {file}`modules/services/databases/postgresql.nix` + +*Upstream documentation:* <http://www.postgresql.org/docs/> + +<!-- FIXME: more stuff, like maintainer? --> + +PostgreSQL is an advanced, free relational database. +<!-- MORE --> + +## Configuring {#module-services-postgres-configuring} + +To enable PostgreSQL, add the following to your {file}`configuration.nix`: +``` +services.postgresql.enable = true; +services.postgresql.package = pkgs.postgresql_11; +``` +Note that you are required to specify the desired version of PostgreSQL (e.g. `pkgs.postgresql_11`). Since upgrading your PostgreSQL version requires a database dump and reload (see below), NixOS cannot provide a default value for [](#opt-services.postgresql.package) such as the most recent release of PostgreSQL. + +<!-- +After running {command}`nixos-rebuild`, you can verify +whether PostgreSQL works by running {command}`psql`: + +```ShellSession +$ psql +psql (9.2.9) +Type "help" for help. + +alice=> +``` +--> + +By default, PostgreSQL stores its databases in {file}`/var/lib/postgresql/$psqlSchema`. You can override this using [](#opt-services.postgresql.dataDir), e.g. +``` +services.postgresql.dataDir = "/data/postgresql"; +``` + +## Upgrading {#module-services-postgres-upgrading} + +::: {.note} +The steps below demonstrate how to upgrade from an older version to `pkgs.postgresql_13`. +These instructions are also applicable to other versions. +::: + +Major PostgreSQL upgrades require a downtime and a few imperative steps to be called. This is the case because +each major version has some internal changes in the databases' state during major releases. Because of that, +NixOS places the state into {file}`/var/lib/postgresql/<version>` where each `version` +can be obtained like this: +``` +$ nix-instantiate --eval -A postgresql_13.psqlSchema +"13" +``` +For an upgrade, a script like this can be used to simplify the process: +``` +{ config, pkgs, ... }: +{ + environment.systemPackages = [ + (let + # XXX specify the postgresql package you'd like to upgrade to. + # Do not forget to list the extensions you need. + newPostgres = pkgs.postgresql_13.withPackages (pp: [ + # pp.plv8 + ]); + in pkgs.writeScriptBin "upgrade-pg-cluster" '' + set -eux + # XXX it's perhaps advisable to stop all services that depend on postgresql + systemctl stop postgresql + + export NEWDATA="/var/lib/postgresql/${newPostgres.psqlSchema}" + + export NEWBIN="${newPostgres}/bin" + + export OLDDATA="${config.services.postgresql.dataDir}" + export OLDBIN="${config.services.postgresql.package}/bin" + + install -d -m 0700 -o postgres -g postgres "$NEWDATA" + cd "$NEWDATA" + sudo -u postgres $NEWBIN/initdb -D "$NEWDATA" + + sudo -u postgres $NEWBIN/pg_upgrade \ + --old-datadir "$OLDDATA" --new-datadir "$NEWDATA" \ + --old-bindir $OLDBIN --new-bindir $NEWBIN \ + "$@" + '') + ]; +} +``` + +The upgrade process is: + + 1. Rebuild nixos configuration with the configuration above added to your {file}`configuration.nix`. Alternatively, add that into separate file and reference it in `imports` list. + 2. Login as root (`sudo su -`) + 3. Run `upgrade-pg-cluster`. It will stop old postgresql, initialize a new one and migrate the old one to the new one. You may supply arguments like `--jobs 4` and `--link` to speedup migration process. See <https://www.postgresql.org/docs/current/pgupgrade.html> for details. + 4. Change postgresql package in NixOS configuration to the one you were upgrading to via [](#opt-services.postgresql.package). Rebuild NixOS. This should start new postgres using upgraded data directory and all services you stopped during the upgrade. + 5. After the upgrade it's advisable to analyze the new cluster. + + - For PostgreSQL ≥ 14, use the `vacuumdb` command printed by the upgrades script. + - For PostgreSQL < 14, run (as `su -l postgres` in the [](#opt-services.postgresql.dataDir), in this example {file}`/var/lib/postgresql/13`): + + ``` + $ ./analyze_new_cluster.sh + ``` + + ::: {.warning} + The next step removes the old state-directory! + ::: + + ``` + $ ./delete_old_cluster.sh + ``` + +## Options {#module-services-postgres-options} + +A complete list of options for the PostgreSQL module may be found [here](#opt-services.postgresql.enable). + +## Plugins {#module-services-postgres-plugins} + +Plugins collection for each PostgreSQL version can be accessed with `.pkgs`. For example, for `pkgs.postgresql_11` package, its plugin collection is accessed by `pkgs.postgresql_11.pkgs`: +```ShellSession +$ nix repl '<nixpkgs>' + +Loading '<nixpkgs>'... +Added 10574 variables. + +nix-repl> postgresql_11.pkgs.<TAB><TAB> +postgresql_11.pkgs.cstore_fdw postgresql_11.pkgs.pg_repack +postgresql_11.pkgs.pg_auto_failover postgresql_11.pkgs.pg_safeupdate +postgresql_11.pkgs.pg_bigm postgresql_11.pkgs.pg_similarity +postgresql_11.pkgs.pg_cron postgresql_11.pkgs.pg_topn +postgresql_11.pkgs.pg_hll postgresql_11.pkgs.pgjwt +postgresql_11.pkgs.pg_partman postgresql_11.pkgs.pgroonga +... +``` + +To add plugins via NixOS configuration, set `services.postgresql.extraPlugins`: +``` +services.postgresql.package = pkgs.postgresql_11; +services.postgresql.extraPlugins = with pkgs.postgresql_11.pkgs; [ + pg_repack + postgis +]; +``` + +You can build custom PostgreSQL-with-plugins (to be used outside of NixOS) using function `.withPackages`. For example, creating a custom PostgreSQL package in an overlay can look like: +``` +self: super: { + postgresql_custom = self.postgresql_11.withPackages (ps: [ + ps.pg_repack + ps.postgis + ]); +} +``` + +Here's a recipe on how to override a particular plugin through an overlay: +``` +self: super: { + postgresql_11 = super.postgresql_11.override { this = self.postgresql_11; } // { + pkgs = super.postgresql_11.pkgs // { + pg_repack = super.postgresql_11.pkgs.pg_repack.overrideAttrs (_: { + name = "pg_repack-v20181024"; + src = self.fetchzip { + url = "https://github.com/reorg/pg_repack/archive/923fa2f3c709a506e111cc963034bf2fd127aa00.tar.gz"; + sha256 = "17k6hq9xaax87yz79j773qyigm4fwk8z4zh5cyp6z0sxnwfqxxw5"; + }; + }); + }; + }; +} +``` |