nixos/postgresql: turn `settings` into a submodule

The main idea behind that was to be able to do more sophisticated
merging for stuff that goes into `postgresql.conf`:
`shared_preload_libraries` is a comma-separated list in a `types.str`
and thus not mergeable. With this change, the option accepts both a
comma-separated string xor a list of strings.

This can be implemented rather quick using `coercedTo` +
freeform modules. The interface still behaves equally, but it allows to
merge declarations for this option together.

One side-effect was that I had to change the `attrsOf (oneOf ...)` part into
a submodule to allow declaring options for certain things. While at it,
I decided to move `log_line_prefix` and `port` into this structure as
well.

nixos/modules/services/databases/postgresql.md

@@ -118,7 +118,7 @@ are already created.
       before = "service1.service";
       after = "postgresql.service";
       serviceConfig.User = "postgres";
-      environment.PSQL = "psql --port=${toString services.postgresql.port}";
+      environment.PSQL = "psql --port=${toString services.postgresql.settings.port}";
       path = [ postgresql ];
       script = ''
         $PSQL service1 -c 'GRANT SELECT ON ALL TABLES IN SCHEMA public TO "extraUser1"'
@@ -139,7 +139,7 @@ are already created.
 
 ```nix
   {
-    environment.PSQL = "psql --port=${toString services.postgresql.port}";
+    environment.PSQL = "psql --port=${toString services.postgresql.settings.port}";
     path = [ postgresql ];
     systemd.services."service1".preStart = ''
       $PSQL -c 'GRANT SELECT ON ALL TABLES IN SCHEMA public TO "extraUser1"'
@@ -159,7 +159,7 @@ are already created.
       before = "service1.service";
       after = "postgresql.service";
       serviceConfig.User = "service1";
-      environment.PSQL = "psql --port=${toString services.postgresql.port}";
+      environment.PSQL = "psql --port=${toString services.postgresql.settings.port}";
       path = [ postgresql ];
       script = ''
         $PSQL -c 'GRANT SELECT ON ALL TABLES IN SCHEMA public TO "extraUser1"'

nixos/modules/services/databases/postgresql.nix

@@ -27,7 +27,7 @@ let
     else toString value;
 
   # The main PostgreSQL configuration file.
-  configFile = pkgs.writeTextDir "postgresql.conf" (concatStringsSep "\n" (mapAttrsToList (n: v: "${n} = ${toStr v}") cfg.settings));
+  configFile = pkgs.writeTextDir "postgresql.conf" (concatStringsSep "\n" (mapAttrsToList (n: v: "${n} = ${toStr v}") (filterAttrs (const (x: x != null)) cfg.settings)));
 
   configFileCheck = pkgs.runCommand "postgresql-configfile-check" {} ''
     ${cfg.package}/bin/postgres -D${configFile} -C config_file >/dev/null
@@ -41,6 +41,9 @@ in
 {
   imports = [
     (mkRemovedOptionModule [ "services" "postgresql" "extraConfig" ] "Use services.postgresql.settings instead.")
+
+    (mkRenamedOptionModule [ "services" "postgresql" "logLinePrefix" ] [ "services" "postgresql" "settings" "log_line_prefix" ])
+    (mkRenamedOptionModule [ "services" "postgresql" "port" ] [ "services" "postgresql" "settings" "port" ])
   ];
 
   ###### interface
@@ -57,14 +60,6 @@ in
         example = "postgresql_15";
       };
 
-      port = mkOption {
-        type = types.port;
-        default = 5432;
-        description = lib.mdDoc ''
-          The port on which PostgreSQL listens.
-        '';
-      };
-
       checkConfig = mkOption {
         type = types.bool;
         default = true;
@@ -352,17 +347,6 @@ in
         '';
       };
 
-      logLinePrefix = mkOption {
-        type = types.str;
-        default = "[%p] ";
-        example = "%m [%p] ";
-        description = lib.mdDoc ''
-          A printf-style string that is output at the beginning of each log line.
-          Upstream default is `'%m [%p] '`, i.e. it includes the timestamp. We do
-          not include the timestamp, because journal has it anyway.
-        '';
-      };
-
       extraPlugins = mkOption {
         type = with types; coercedTo (listOf path) (path: _ignorePg: path) (functionTo (listOf path));
         default = _: [];
@@ -373,7 +357,38 @@ in
       };
 
       settings = mkOption {
-        type = with types; attrsOf (oneOf [ bool float int str ]);
+        type = with types; submodule {
+          freeformType = attrsOf (oneOf [ bool float int str ]);
+          options = {
+            shared_preload_libraries = mkOption {
+              type = nullOr (coercedTo (listOf str) (concatStringsSep ", ") str);
+              default = null;
+              example = literalExpression ''[ "auto_explain" "anon" ]'';
+              description = mdDoc ''
+                List of libraries to be preloaded.
+              '';
+            };
+
+            log_line_prefix = mkOption {
+              type = types.str;
+              default = "[%p] ";
+              example = "%m [%p] ";
+              description = lib.mdDoc ''
+                A printf-style string that is output at the beginning of each log line.
+                Upstream default is `'%m [%p] '`, i.e. it includes the timestamp. We do
+                not include the timestamp, because journal has it anyway.
+              '';
+            };
+
+            port = mkOption {
+              type = types.port;
+              default = 5432;
+              description = lib.mdDoc ''
+                The port on which PostgreSQL listens.
+              '';
+            };
+          };
+        };
         default = {};
         description = lib.mdDoc ''
           PostgreSQL configuration. Refer to
@@ -439,9 +454,7 @@ in
         hba_file = "${pkgs.writeText "pg_hba.conf" cfg.authentication}";
         ident_file = "${pkgs.writeText "pg_ident.conf" cfg.identMap}";
         log_destination = "stderr";
-        log_line_prefix = cfg.logLinePrefix;
         listen_addresses = if cfg.enableTCPIP then "*" else "localhost";
-        port = cfg.port;
         jit = mkDefault (if cfg.enableJIT then "on" else "off");
       };
 
@@ -524,7 +537,7 @@ in
         # Wait for PostgreSQL to be ready to accept connections.
         postStart =
           ''
-            PSQL="psql --port=${toString cfg.port}"
+            PSQL="psql --port=${toString cfg.settings.port}"
 
             while ! $PSQL -d postgres -c "" 2> /dev/null; do
                 if ! kill -0 "$MAINPID"; then exit 1; fi

nixos/modules/services/misc/forgejo.nix

@@ -114,11 +114,11 @@ in
 
         port = mkOption {
           type = types.port;
-          default = if !usePostgresql then 3306 else pg.port;
+          default = if usePostgresql then pg.settings.port else 3306;
           defaultText = literalExpression ''
             if config.${opt.database.type} != "postgresql"
             then 3306
-            else config.${options.services.postgresql.port}
+            else 5432
           '';
           description = mdDoc "Database host port.";
         };

nixos/modules/services/misc/gitea.nix

@@ -100,11 +100,11 @@ in
 
         port = mkOption {
           type = types.port;
-          default = if !usePostgresql then 3306 else pg.port;
+          default = if usePostgresql then pg.settings.port else 3306;
           defaultText = literalExpression ''
             if config.${opt.database.type} != "postgresql"
             then 3306
-            else config.${options.services.postgresql.port}
+            else 5432
           '';
           description = lib.mdDoc "Database host port.";
         };

nixos/modules/services/monitoring/zabbix-proxy.nix

@@ -103,11 +103,11 @@ in
 
         port = mkOption {
           type = types.port;
-          default = if cfg.database.type == "mysql" then mysql.port else pgsql.port;
+          default = if cfg.database.type == "mysql" then mysql.port else pgsql.services.port;
           defaultText = literalExpression ''
             if config.${opt.database.type} == "mysql"
             then config.${options.services.mysql.port}
-            else config.${options.services.postgresql.port}
+            else config.services.postgresql.settings.port
           '';
           description = lib.mdDoc "Database host port.";
         };

nixos/modules/services/monitoring/zabbix-server.nix

@@ -95,11 +95,11 @@ in
 
         port = mkOption {
           type = types.port;
-          default = if cfg.database.type == "mysql" then mysql.port else pgsql.port;
+          default = if cfg.database.type == "mysql" then mysql.port else pgsql.settings.port;
           defaultText = literalExpression ''
             if config.${opt.database.type} == "mysql"
             then config.${options.services.mysql.port}
-            else config.${options.services.postgresql.port}
+            else config.services.postgresql.settings.port
           '';
           description = lib.mdDoc "Database host port.";
         };

nixos/modules/services/web-apps/invidious.nix

@@ -346,8 +346,8 @@ in
 
       port = lib.mkOption {
         type = types.port;
-        default = options.services.postgresql.port.default;
-        defaultText = lib.literalExpression "options.services.postgresql.port.default";
+        default = config.services.postgresql.settings.port;
+        defaultText = lib.literalExpression "config.services.postgresql.settings.port";
         description = lib.mdDoc ''
           The port of the database Invidious should use.
 

nixos/modules/services/web-apps/zabbix.nix

@@ -76,11 +76,11 @@ in
           type = types.port;
           default =
             if cfg.database.type == "mysql" then config.services.mysql.port
-            else if cfg.database.type == "pgsql" then config.services.postgresql.port
+            else if cfg.database.type == "pgsql" then config.services.postgresql.settings.port
             else 1521;
           defaultText = literalExpression ''
             if config.${opt.database.type} == "mysql" then config.${options.services.mysql.port}
-            else if config.${opt.database.type} == "pgsql" then config.${options.services.postgresql.port}
+            else if config.${opt.database.type} == "pgsql" then config.services.postgresql.settings.port
             else 1521
           '';
           description = lib.mdDoc "Database host port.";

nixos/tests/invidious.nix

@@ -18,7 +18,7 @@ import ./make-test-python.nix ({ pkgs, ... }: {
           host invidious invidious samenet scram-sha-256
         '';
       };
-      networking.firewall.allowedTCPPorts = [ config.services.postgresql.port ];
+      networking.firewall.allowedTCPPorts = [ config.services.postgresql.settings.port ];
     };
     machine = { config, lib, pkgs, ... }: {
       services.invidious = {

nixos/tests/miniflux.nix

@@ -76,7 +76,7 @@ in
       systemd.services.postgresql.postStart = lib.mkAfter ''
         $PSQL -tAd miniflux -c 'CREATE EXTENSION hstore;'
       '';
-      networking.firewall.allowedTCPPorts = [ config.services.postgresql.port ];
+      networking.firewall.allowedTCPPorts = [ config.services.postgresql.settings.port ];
     };
     externalDb = { ... }: {
       security.apparmor.enable = true;

nixos/tests/pg_anonymizer.nix

@@ -7,7 +7,7 @@ import ./make-test-python.nix ({ pkgs, lib, ... }: {
     services.postgresql = {
       enable = true;
       extraPlugins = ps: [ ps.anonymizer ];
-      settings.shared_preload_libraries = "anon";
+      settings.shared_preload_libraries = [ "anon" ];
     };
   };
 

nixos/tests/pgmanage.nix

@@ -21,7 +21,7 @@ in
         pgmanage = {
           enable = true;
           connections = {
-            ${conn} = "hostaddr=127.0.0.1 port=${toString config.services.postgresql.port} dbname=postgres";
+            ${conn} = "hostaddr=127.0.0.1 port=${toString config.services.postgresql.settings.port} dbname=postgres";
           };
         };
       };

nixos/tests/web-apps/mastodon/remote-databases.nix

@@ -33,7 +33,7 @@ in
         extraHosts = hosts;
         firewall.allowedTCPPorts = [
           config.services.redis.servers.mastodon.port
-          config.services.postgresql.port
+          config.services.postgresql.settings.port
         ];
       };