modules: services: postgres: add migration script

The process to upgrade is:

* Make sure the version number of the script is one major version over
  the service version.

* Activate the script, rebuild configuration.

* Run `upgrade-pg-cluster` as `root`. One can give arguments like
  `--link` or `--jobs 4` to speedup the process. See documentation for
  some details.

* Change package to new version once the upgrade is finished, rebuild
  configuration.

* Optionally, `ANALYZE` the new database.
This commit is contained in:
Bruno BELANYI 2021-07-29 12:44:42 +02:00
parent 9f00d8a38e
commit bbb1231ad3

View file

@ -5,6 +5,9 @@ in
{
options.my.services.postgresql = with lib; {
enable = my.mkDisableOption "postgres configuration";
# Transient option to be enabled for migrations
upgradeScript = mkEnableOption "postgres upgrade script";
};
config = lib.mkMerge [
@ -14,5 +17,45 @@ in
package = pkgs.postgresql_12;
};
})
# Taken from the manual
(lib.mkIf cfg.upgradeScript {
containers.temp-pg.config.services.postgresql = {
enable = true;
package = pkgs.postgresql_13;
};
environment.systemPackages =
let
newpg = config.containers.temp-pg.config.services.postgresql;
in
[
(pkgs.writeScriptBin "upgrade-pg-cluster" ''
#!/usr/bin/env bash
set -x
export OLDDATA="${config.services.postgresql.dataDir}"
export NEWDATA="${newpg.dataDir}"
export OLDBIN="${config.services.postgresql.package}/bin"
export NEWBIN="${newpg.package}/bin"
if [ "$OLDDATA" -ef "$NEWDATA" ]; then
echo "Cannot migrate to same data directory" >&2
exit 1
fi
install -d -m 0700 -o postgres -g postgres "$NEWDATA"
cd "$NEWDATA"
sudo -u postgres $NEWBIN/initdb -D "$NEWDATA"
systemctl stop postgresql # old one
sudo -u postgres $NEWBIN/pg_upgrade \
--old-datadir "$OLDDATA" --new-datadir "$NEWDATA" \
--old-bindir $OLDBIN --new-bindir $NEWBIN \
"$@"
'')
];
})
];
}