nixos/varnish: turn listen addresses into structured config (#421481)

nixos/doc/manual/release-notes/rl-2511.section.md

···
 - `amdgpu` kernel driver overdrive mode can now be enabled by setting [hardware.amdgpu.overdrive.enable](#opt-hardware.amdgpu.overdrive.enable) and customized through [hardware.amdgpu.overdrive.ppfeaturemask](#opt-hardware.amdgpu.overdrive.ppfeaturemask).
   This allows for fine-grained control over the GPU's performance and maybe required by overclocking softwares like Corectrl and Lact. These new options replace old options such as {option}`programs.corectrl.gpuOverclock.enable` and {option}`programs.tuxclocker.enableAMD`.
 
+- `services.varnish.http_address` has been superseeded by `services.varnish.listen` which is now
+  structured config for all of varnish's `-a` variations.
+
 - [](#opt-services.gnome.gnome-keyring.enable) does not ship with an SSH agent anymore, as this is now handled by the `gcr_4` package instead of `gnome-keyring`. A new module has been added to support this, under [](#opt-services.gnome.gcr-ssh-agent.enable) (its default value has been set to [](#opt-services.gnome.gnome-keyring.enable) to ensure a smooth transition). See the [relevant upstream PR](https://gitlab.gnome.org/GNOME/gcr/-/merge_requests/67) for more details.
 
 - The `nettools` package (ifconfig, arp, mii-tool, netstat, route) is not installed by default anymore. The suite is unmaintained and users should migrate to `iproute2` and `ethtool` instead.

nixos/modules/services/web-servers/varnish/default.nix

···
 }:
 
 let
+  inherit (lib)
+    types
+    mkOption
+    hasPrefix
+    concatMapStringsSep
+    optionalString
+    concatMap
+    ;
+  inherit (builtins) isNull;
+
   cfg = config.services.varnish;
 
   # Varnish has very strong opinions and very complicated code around handling
···
     else
       "/var/run/varnishd";
 
+  # from --help:
+  #   -a [<name>=]address[:port][,proto] # HTTP listen address and port
+  #      [,user=<u>][,group=<g>]   # Can be specified multiple times.
+  #      [,mode=<m>]               #   default: ":80,HTTP"
+  #                                # Proto can be "PROXY" or "HTTP" (default)
+  #                                # user, group and mode set permissions for
+  #                                #   a Unix domain socket.
+  commandLineAddresses =
+    (concatMapStringsSep " " (
+      a:
+      "-a "
+      + optionalString (!isNull a.name) "${a.name}="
+      + a.address
+      + optionalString (!isNull a.port) ":${toString a.port}"
+      + optionalString (!isNull a.proto) ",${a.proto}"
+      + optionalString (!isNull a.user) ",user=${a.user}"
+      + optionalString (!isNull a.group) ",group=${a.group}"
+      + optionalString (!isNull a.mode) ",mode=${a.mode}"
+    ) cfg.listen)
+    + lib.optionalString (!isNull cfg.http_address) " -a ${cfg.http_address}";
+  addressSubmodule = types.submodule {
+    options = {
+      name = mkOption {
+        description = "Name is referenced in logs. If name is not specified, 'a0', 'a1', etc. is used.";
+        default = null;
+        type = with types; nullOr str;
+      };
+      address = mkOption {
+        description = ''
+          If given an IP address, it can be a host name ("localhost"), an IPv4 dotted-quad
+          ("127.0.0.1") or an IPv6  address enclosed in square brackets ("[::1]").
+
+          (VCL4.1 and higher) If given an absolute Path ("/path/to/listen.sock") or "@"
+          followed by the name of an abstract socket ("@myvarnishd") accept connections
+          on a Unix domain socket.
+
+          The user, group and mode sub-arguments may be used to specify the permissions
+          of the socket file. These sub-arguments do not apply to  abstract sockets.
+        '';
+        type = types.str;
+      };
+      port = mkOption {
+        description = "The port to use for IP sockets. If port is not specified, port 80 (http) is used.";
+        default = null;
+        type = with types; nullOr int;
+      };
+      proto = mkOption {
+        description = "PROTO can be 'HTTP' (the default) or 'PROXY'.  Both version 1 and 2 of the proxy protocol can be used.";
+        type = types.enum [
+          "HTTP"
+          "PROXY"
+        ];
+        default = "HTTP";
+      };
+      user = mkOption {
+        description = "User name who owns the socket file.";
+        default = null;
+        type = with lib.types; nullOr str;
+      };
+      group = mkOption {
+        description = "Group name who owns the socket file.";
+        default = null;
+        type = with lib.types; nullOr str;
+      };
+      mode = mkOption {
+        description = "Permission of the socket file (3-digit octal value).";
+        default = null;
+        type = with types; nullOr str;
+      };
+    };
+  };
+  checkedAddressModule = types.addCheck addressSubmodule (
+    m:
+    (
+      if ((hasPrefix "@" m.address) || (hasPrefix "/" m.address)) then
+        # this is a unix socket
+        (m.port != null)
+      else
+      # this is not a path-based unix socket
+      if !(hasPrefix "/" m.address) && (m.group != null) || (m.user != null) || (m.mode != null) then
+        false
+      else
+        true
+    )
+  );
   commandLine =
     "-f ${pkgs.writeText "default.vcl" cfg.config}"
     +
···
       package = lib.mkPackageOption pkgs "varnish" { };
 
       http_address = lib.mkOption {
-        type = lib.types.str;
-        default = "*:6081";
+        type = with lib.types; nullOr str;
+        default = null;
         description = ''
           HTTP listen address and port.
         '';
+      };
+
+      listen = lib.mkOption {
+        description = "Accept for client requests on the specified listen addresses.";
+        type = lib.types.listOf checkedAddressModule;
+        defaultText = lib.literalExpression ''[ { address="*"; port=6081; } ]'';
+        default = lib.optional (isNull cfg.http_address) {
+          address = "*";
+          port = 6081;
+        };
       };
 
       config = lib.mkOption {
···
       serviceConfig = {
         Type = "simple";
         PermissionsStartOnly = true;
-        ExecStart = "${cfg.package}/sbin/varnishd -a ${cfg.http_address} -n ${stateDir} -F ${cfg.extraCommandLine} ${commandLine}";
+        ExecStart = "${cfg.package}/sbin/varnishd ${commandLineAddresses} -n ${stateDir} -F ${cfg.extraCommandLine} ${commandLine}";
         Restart = "always";
         RestartSec = "5s";
         User = "varnish";
···
         ${cfg.package}/bin/varnishd -C ${commandLine} 2> $out || (cat $out; exit 1)
       '')
     ];
+
+    assertions = concatMap (m: [
+      {
+        assertion = (hasPrefix "/" m.address) || (hasPrefix "@" m.address) -> m.port == null;
+        message = "Listen ports must not be specified with UNIX sockets: ${builtins.toJSON m}";
+      }
+      {
+        assertion = !(hasPrefix "/" m.address) -> m.user == null && m.group == null && m.mode == null;
+        message = "Abstract UNIX sockets or IP sockets can not be used with user, group, and mode settings: ${builtins.toJSON m}";
+      }
+    ]) cfg.listen;
+
+    warnings =
+      lib.optional (!isNull cfg.http_address)
+        "The option `services.varnish.http_address` is deprecated. Use `services.varnish.listen` instead.";
 
     users.users.varnish = {
       group = "varnish";

nixos/tests/varnish.nix

···
 
   nodes = {
     varnish =
-      { config, pkgs, ... }:
+      {
+        config,
+        pkgs,
+        lib,
+        ...
+      }:
       {
         services.nix-serve = {
           enable = true;
···
         services.varnish = {
           inherit package;
           enable = true;
-          http_address = "0.0.0.0:80";
+          http_address = "0.0.0.0:81";
+          listen = [
+            {
+              address = "0.0.0.0";
+              port = 80;
+              proto = "HTTP";
+            }
+            {
+              name = "proxyport";
+              address = "0.0.0.0";
+              port = 8080;
+              proto = "PROXY";
+            }
+            { address = "@asdf"; }
+            {
+              address = "/run/varnishd/client.http.sock";
+              user = "varnish";
+              group = "varnish";
+              mode = "660";
+            }
+          ];
           config = ''
-            vcl 4.0;
+            vcl 4.1;
 
             backend nix-serve {
               .host = "127.0.0.1";
···
 
         networking.firewall.allowedTCPPorts = [ 80 ];
         system.extraDependencies = [ testPath ];
+
+        assertions =
+          map
+            (
+              pattern:
+              let
+                cmdline = config.systemd.services.varnish.serviceConfig.ExecStart;
+              in
+              {
+                assertion = lib.hasInfix pattern cmdline;
+                message = "Address argument `${pattern}` missing in commandline `${cmdline}`.";
+              }
+            )
+            [
+              " -a 0.0.0.0:80,HTTP "
+              " -a proxyport=0.0.0.0:8080,PROXY "
+              " -a @asdf,HTTP "
+              " -a /run/varnishd/client.http.sock,HTTP,user=varnish,group=varnish,mode=660 "
+              " -a 0.0.0.0:81 "
+            ];
       };
 
     client =
···
   testScript = ''
     start_all()
     varnish.wait_for_open_port(80)
+
 
     client.wait_until_succeeds("curl -f http://varnish/nix-cache-info");