services/postsrsd: updates for postsrsd 2

postsrsd 2 expects a config file, and has some breaking changes that
make it incompatible with some of our old options.

doc/release-notes/rl-2505.section.md

@@ -58,6 +58,10 @@
   OpenSMTPD 7.6.0 or later. The package has been removed in favor of a set of new
   `opensmtpd-table-*` packages.
 
+- `postsrsd` upgraded to `>= 2.0.0`, with some different behaviors and
+  configuration settings. Notably, it now defaults to listening on a socket
+  rather than a port. See [Migrating from version 1.x](https://github.com/roehling/postsrsd/blob/2.0.10/README.rst#migrating-from-version-1x) and [Postfix Setup](https://github.com/roehling/postsrsd?tab=readme-ov-file#postfix-setup) for details.
+
 - The hand written `perlPackages.SearchXapian` bindings have been dropped in favor of the (mostly compatible)
   `perlPackages.Xapian`.
 

nixos/modules/services/mail/postsrsd.nix

@@ -7,16 +7,52 @@
 let
 
   cfg = config.services.postsrsd;
+  runtimeDirectoryName = "postsrsd";
+  runtimeDirectory = "/run/${runtimeDirectoryName}";
+  # TODO: follow RFC 42, but we need a libconfuse format first:
+  #       https://github.com/NixOS/nixpkgs/issues/401565
+  # Arrays in `libconfuse` look like this: {"Life", "Universe", "Everything"}
+  # See https://www.nongnu.org/confuse/tutorial-html/ar01s03.html.
+  #
+  # Note: We're using `builtins.toJSON` to escape strings, but JSON strings
+  # don't have exactly the same semantics as libconfuse strings. For example,
+  # "${F}" gets treated as an env var reference, see above issue for details.
+  libconfuseDomains = "{ " + lib.concatMapStringsSep ", " builtins.toJSON cfg.domains + " }";
+  configFile = pkgs.writeText "postsrsd.conf" ''
+    secrets-file = "''${CREDENTIALS_DIRECTORY}/secrets-file"
+    domains = ${libconfuseDomains}
+    separator = "${cfg.separator}"
+    socketmap = "unix:${runtimeDirectory}/socket"
+
+    # Disable postsrsd's jailing in favor of confinement with systemd.
+    unprivileged-user = ""
+    chroot-dir = ""
+  '';
 
 in
 {
-
-  ###### interface
+  imports =
+    map
+      (
+        name:
+        lib.mkRemovedOptionModule [ "services" "postsrsd" name ] ''
+          `postsrsd` was upgraded to `>= 2.0.0`, with some different behaviors and configuration settings:
+            - NixOS Release Notes: https://nixos.org/manual/nixos/unstable/release-notes#sec-nixpkgs-release-25.05-incompatibilities
+            - NixOS Options Reference: https://nixos.org/manual/nixos/unstable/options#opt-services.postsrsd.enable
+            - Migration instructions: https://github.com/roehling/postsrsd/blob/2.0.10/README.rst#migrating-from-version-1x
+            - Postfix Setup: https://github.com/roehling/postsrsd/blob/2.0.10/README.rst#postfix-setup
+        ''
+      )
+      [
+        "domain"
+        "forwardPort"
+        "reversePort"
+        "timeout"
+        "excludeDomains"
+      ];
 
   options = {
-
     services.postsrsd = {
-
       enable = lib.mkOption {
         type = lib.types.bool;
         default = false;
@@ -29,9 +65,11 @@ in
         description = "Secret keys used for signing and verification";
       };
 
-      domain = lib.mkOption {
-        type = lib.types.str;
-        description = "Domain name for rewrite";
+      domains = lib.mkOption {
+        type = lib.types.listOf lib.types.str;
+        description = "Domain names for rewrite";
+        default = [ config.networking.hostName ];
+        defaultText = lib.literalExpression "[ config.networking.hostName ]";
       };
 
       separator = lib.mkOption {
@@ -44,36 +82,6 @@ in
         description = "First separator character in generated addresses";
       };
 
-      # bindAddress = lib.mkOption { # uncomment once 1.5 is released
-      #   type = lib.types.str;
-      #   default = "127.0.0.1";
-      #   description = "Socket listen address";
-      # };
-
-      forwardPort = lib.mkOption {
-        type = lib.types.int;
-        default = 10001;
-        description = "Port for the forward SRS lookup";
-      };
-
-      reversePort = lib.mkOption {
-        type = lib.types.int;
-        default = 10002;
-        description = "Port for the reverse SRS lookup";
-      };
-
-      timeout = lib.mkOption {
-        type = lib.types.int;
-        default = 1800;
-        description = "Timeout for idle client connections in seconds";
-      };
-
-      excludeDomains = lib.mkOption {
-        type = lib.types.listOf lib.types.str;
-        default = [ ];
-        description = "Origin domains to exclude from rewriting in addition to primary domain";
-      };
-
       user = lib.mkOption {
         type = lib.types.str;
         default = "postsrsd";
@@ -85,17 +93,10 @@ in
         default = "postsrsd";
         description = "Group for the daemon";
       };
-
     };
-
   };
 
-  ###### implementation
-
   config = lib.mkIf cfg.enable {
-
-    services.postsrsd.domain = lib.mkDefault config.networking.hostName;
-
     users.users = lib.optionalAttrs (cfg.user == "postsrsd") {
       postsrsd = {
         group = cfg.group;
@@ -107,30 +108,42 @@ in
       postsrsd.gid = config.ids.gids.postsrsd;
     };
 
-    systemd.services.postsrsd = {
-      description = "PostSRSd SRS rewriting server";
-      after = [ "network.target" ];
-      before = [ "postfix.service" ];
-      wantedBy = [ "multi-user.target" ];
-
+    systemd.services.postsrsd-generate-secrets = {
       path = [ pkgs.coreutils ];
-
-      serviceConfig = {
-        ExecStart = ''${pkgs.postsrsd}/sbin/postsrsd "-s${cfg.secretsFile}" "-d${cfg.domain}" -a${cfg.separator} -f${toString cfg.forwardPort} -r${toString cfg.reversePort} -t${toString cfg.timeout} "-X${lib.concatStringsSep "," cfg.excludeDomains}"'';
-        User = cfg.user;
-        Group = cfg.group;
-        PermissionsStartOnly = true;
-      };
-
-      preStart = ''
-        if [ ! -e "${cfg.secretsFile}" ]; then
+      script = ''
+        if [ -e "${cfg.secretsFile}" ]; then
+          echo "Secrets file exists. Nothing to do!"
+        else
           echo "WARNING: secrets file not found, autogenerating!"
           DIR="$(dirname "${cfg.secretsFile}")"
           install -m 750 -o ${cfg.user} -g ${cfg.group} -d "$DIR"
           install -m 600 -o ${cfg.user} -g ${cfg.group} <(dd if=/dev/random bs=18 count=1 | base64) "${cfg.secretsFile}"
         fi
       '';
+      serviceConfig = {
+        Type = "oneshot";
+      };
     };
 
+    systemd.services.postsrsd = {
+      description = "PostSRSd SRS rewriting server";
+      after = [
+        "network.target"
+        "postsrsd-generate-secrets.service"
+      ];
+      before = [ "postfix.service" ];
+      wantedBy = [ "multi-user.target" ];
+      requires = [ "postsrsd-generate-secrets.service" ];
+      confinement.enable = true;
+
+      serviceConfig = {
+        ExecStart = "${lib.getExe pkgs.postsrsd} -C ${configFile}";
+        User = cfg.user;
+        Group = cfg.group;
+        PermissionsStartOnly = true;
+        RuntimeDirectory = runtimeDirectoryName;
+        LoadCredential = "secrets-file:${cfg.secretsFile}";
+      };
+    };
   };
 }