feat: PostgreSQL migration

postgresql/upgrade12to16.nix

@@ -0,0 +1,130 @@
+{ config, lib, pkgs, ... }:
+
+let
+  cfg = config.services.postgresqlUpgrade12to16;
+  mkIf = lib.mkIf;
+  mkOption = lib.mkOption;
+  types = lib.types;
+  optional = lib.optional;
+in
+
+{
+  options.services.postgresqlUpgrade12to16 = {
+    enable = mkOption {
+      type = types.bool;
+      default = false;
+      description = ''
+        Enables an automatic one-shot upgrade from PostgreSQL 12 to 16 if a
+        version 12 data directory is found. This will run pg_upgrade and may
+        take time depending on database size. Use with caution.
+      '';
+    };
+    dataDir12 = mkOption {
+      type = types.str;
+      default = "/var/lib/postgresql/12";
+      description = "Location of the old PostgreSQL 12 data directory.";
+    };
+    dataDir16 = mkOption {
+      type = types.str;
+      default = "/var/lib/postgresql/16";
+      description = "Location of the new PostgreSQL 16 data directory.";
+    };
+    pleromaEnabled = mkOption {
+      type = types.bool;
+      default = false;
+      description = ''
+        Whether Pleroma service is present and needs to be stopped/started
+        during the PostgreSQL upgrade process.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    assertions = [
+      {
+        assertion = config.services.postgresql.package == pkgs.postgresql_16;
+        message = "PostgreSQL package must be set to postgresql_16 for the upgrade to work correctly.";
+      }
+      {
+        assertion = config.services.postgresql.dataDir == cfg.dataDir16;
+        message = "PostgreSQL data directory must be set to ${cfg.dataDir16} for the upgrade to work correctly. The current value is ${config.services.postgresql.dataDir}.";
+      }
+    ];
+
+    systemd.services."postgresql-upgrade12to16" = {
+      description = "Upgrade PostgreSQL 12 database to PostgreSQL 16";
+      wantedBy = [ "multi-user.target" ];
+      before = [ "postgresql.service" ];
+      after = [ "network-online.target" ];
+      wants = [ "network-online.target" ];
+      serviceConfig = {
+        Type = "oneshot";
+
+        ExecStartPre =
+          # Stop Pleroma only if pleromaEnabled is true
+          optional cfg.pleromaEnabled "${pkgs.writeShellScript "postgresql-upgrade12to16-pre.sh" ''
+            if [ -d "${cfg.dataDir12}" ] && [ ! -d "${cfg.dataDir16}" ]; then
+              ${pkgs.systemd}/bin/systemctl stop pleroma.service
+            fi
+            ''
+            }";
+
+        ExecStart = "${pkgs.writeShellScript "postgresql-upgrade12to16.sh" ''
+            set -e
+
+            oldDataDir="${cfg.dataDir12}"
+            newDataDir="${cfg.dataDir16}"
+
+            # Only upgrade if old data directory exists, and the new one doesn't yet
+            if [ -d "$oldDataDir" ] && [ ! -d "$newDataDir" ]; then
+              echo "Detected PostgreSQL 12 data directory at $oldDataDir"
+              echo "Upgrading to PostgreSQL 16 data directory at $newDataDir"
+
+              # Stop the old PostgreSQL if it's running
+              if systemctl is-active --quiet postgresql.service; then
+                systemctl stop postgresql.service
+              fi
+
+              # Create the new data directory (if not already present)
+              mkdir -p "$newDataDir"
+              chown -R postgres:postgres "$(dirname "$newDataDir")"
+
+              # Create a temporary working directory
+              tempDir=$(mktemp -d)
+              chown -R postgres:postgres "$tempDir"
+              trap 'rm -rf "$tempDir"' EXIT
+
+              # Change to the temporary working directory
+              cd "$tempDir"
+
+              # Initialize the new PostgreSQL 16 data directory
+              ${pkgs.sudo}/bin/sudo -u postgres ${pkgs.postgresql_16.out}/bin/initdb -D "$newDataDir" -U postgres
+
+              # Run pg_upgrade as the postgres user
+              ${pkgs.sudo}/bin/sudo -u postgres ${pkgs.postgresql_16.out}/bin/pg_upgrade \
+                --old-datadir "$oldDataDir" \
+                --new-datadir "$newDataDir" \
+                --old-bindir ${pkgs.postgresql_12.out}/bin \
+                --new-bindir ${pkgs.postgresql_16.out}/bin \
+                --jobs "$(nproc)" \
+                --link \
+                --verbose
+
+              echo "PostgreSQL upgrade from 12 to 16 completed."
+            else
+              echo "No PostgreSQL 12 data directory detected or already upgraded. Skipping."
+            fi
+          ''}";
+
+        # Start Pleroma only if pleromaEnabled is true
+        ExecStartPost =
+          optional cfg.pleromaEnabled "${pkgs.writeShellScript "postgresql-upgrade12to16-pre.sh" ''
+            if [ -d "${cfg.dataDir12}" ] && [ ! -d "${cfg.dataDir16}" ]; then
+              ${pkgs.systemd}/bin/systemctl start --no-block pleroma.service
+            fi
+            ''
+            }";
+      };
+    };
+  };
+}