backup: add a way to stop services before restoring a state.

checks/postgresql/default.nix

@@ -11,8 +11,19 @@
       ];
       clan.postgresql.users.test = { };
       clan.postgresql.databases.test.create.options.OWNER = "test";
+      clan.postgresql.databases.test.restore.stopOnRestore = [ "sample-service" ];
       clan.localbackup.targets.hdd.directory = "/mnt/external-disk";
 
+      systemd.services.sample-service = {
+        wantedBy = [ "multi-user.target" ];
+        script = ''
+          while true; do
+            echo "Hello, world!"
+            sleep 5
+          done
+        '';
+      };
+
       environment.systemPackages = [ config.services.postgresql.package ];
     };
   testScript =
@@ -20,20 +31,22 @@
     ''
       start_all()
       machine.wait_for_unit("postgresql")
+      machine.wait_for_unit("sample-service")
       # Create a test table
       machine.succeed("runuser -u postgres -- /run/current-system/sw/bin/psql -c 'CREATE TABLE test (id serial PRIMARY KEY);' test")
 
       machine.succeed("/run/current-system/sw/bin/localbackup-create >&2")
+      timestamp_before = int(machine.succeed("systemctl show --property=ExecMainStartTimestampMonotonic sample-service | cut -d= -f2").strip())
 
-      machine.succeed("test -e /mnt/external-disk/snapshot.0/machine/var/backup/postgres/test/dump.sql.zstd || { echo 'dump.sql.zstd not found'; exit 1; }")
+      machine.succeed("test -e /mnt/external-disk/snapshot.0/machine/var/backup/postgres/test/pg-dump || { echo 'pg-dump not found'; exit 1; }")
       machine.succeed("runuser -u postgres -- /run/current-system/sw/bin/psql -d test -c 'INSERT INTO test DEFAULT VALUES;'")
       machine.succeed("runuser -u postgres -- /run/current-system/sw/bin/psql -d test -c 'DROP TABLE test;'")
-      machine.succeed("test -e /var/backup/postgres/test/dump.sql.zstd || { echo 'backup.info not found'; exit 1; }")
+      machine.succeed("test -e /var/backup/postgres/test/pg-dump || { echo 'pg-dump not found'; exit 1; }")
 
       machine.succeed("rm -rf /var/backup/postgres")
 
       machine.succeed("NAME=/mnt/external-disk/snapshot.0 FOLDERS=/var/backup/postgres/test /run/current-system/sw/bin/localbackup-restore >&2")
-      machine.succeed("test -e /var/backup/postgres/test/dump.sql.zstd || { echo 'backup.info not found'; exit 1; }")
+      machine.succeed("test -e /var/backup/postgres/test/pg-dump || { echo 'pg-dump not found'; exit 1; }")
 
       machine.succeed("""
       set -x
@@ -42,6 +55,9 @@
       machine.succeed("runuser -u postgres -- /run/current-system/sw/bin/psql -l >&2")
       machine.succeed("runuser -u postgres -- /run/current-system/sw/bin/psql -d test -c '\dt' >&2")
 
+      timestamp_after = int(machine.succeed("systemctl show --property=ExecMainStartTimestampMonotonic sample-service | cut -d= -f2").strip())
+      assert timestamp_before < timestamp_after, f"{timestamp_before} >= {timestamp_after}: expected sample-service to be restarted after restore"
+
       # Check that the table is still there
       machine.succeed("runuser -u postgres -- /run/current-system/sw/bin/psql -d test -c 'SELECT * FROM test;'")
       output = machine.succeed("runuser -u postgres -- /run/current-system/sw/bin/psql --csv -c \"SELECT datdba::regrole FROM pg_database WHERE datname = 'test'\"")

clanModules/postgresql/default.nix

@@ -9,7 +9,8 @@ let
     db:
     let
       folder = "/var/backup/postgres/${db.name}";
-      current = "${folder}/dump.sql.zstd";
+      current = "${folder}/pg-dump";
+      compression = lib.optionalString (lib.versionAtLeast config.services.postgresql.package.version "16") "--compress=zstd";
     in
     {
       folders = [ folder ];
@@ -28,10 +29,9 @@ let
         done
 
         mkdir -p "${folder}"
-        runuser -u postgres -- pg_dump --compress=zstd --dbname=${db.name} -Fc -c > "${current}.tmp"
+        runuser -u postgres -- pg_dump ${compression} --dbname=${db.name} -Fc -c > "${current}.tmp"
         mv "${current}.tmp" ${current}
       '';
-
       postRestoreCommand = ''
         export PATH=${
           lib.makeBinPath [
@@ -52,10 +52,14 @@ let
         done
 
         if [[ -e "${current}" ]]; then
-          umask 077 # only root can read the backup
-          mkdir -p "${folder}"
-          runuser -u postgres -- dropdb "${db.name}"
-          runuser -u postgres -- pg_restore -C -d postgres "${current}"
+          (
+            systemctl stop ${lib.concatStringsSep " " db.restore.stopOnRestore}
+            trap "systemctl start ${lib.concatStringsSep " " db.restore.stopOnRestore}" EXIT
+
+            mkdir -p "${folder}"
+            runuser -u postgres -- dropdb "${db.name}"
+            runuser -u postgres -- pg_restore -C -d postgres "${current}"
+          )
         else
           echo No database backup found, skipping restore
         fi
@@ -111,10 +115,10 @@ in
                   OWNER = "foo";
                 };
               };
-              backup.enable = lib.mkOption {
-                type = lib.types.bool;
-                default = true;
-                description = "Backup the database.";
+              restore.stopOnRestore = lib.mkOption {
+                type = lib.types.listOf lib.types.str;
+                default = [ ];
+                description = "List of services to stop before restoring the database.";
               };
             };
           }

nixosModules/clanCore/state.nix

@@ -33,6 +33,18 @@
                 e.g. a database dump
               '';
             };
+
+            # TODO: implement this
+            #stopOnRestore = lib.mkOption {
+            #  type = lib.types.listOf lib.types.str;
+            #  default = [];
+            #  description = ''
+            #    List of services to stop before restoring the state dir from a backup
+
+            #    Utilize this to stop services which currently access these folders or or other services affected by the restore
+            #  '';
+            #};
+
             preRestoreCommand = lib.mkOption {
               type = lib.types.nullOr lib.types.str;
               default = null;
@@ -42,6 +54,7 @@
                 Utilize this to stop services which currently access these folders
               '';
             };
+
             postRestoreCommand = lib.mkOption {
               type = lib.types.nullOr lib.types.str;
               default = null;