nixos/pomerium: init

nixos/modules/module-list.nix

@@ -948,6 +948,7 @@
   ./services/web-servers/nginx/default.nix
   ./services/web-servers/nginx/gitweb.nix
   ./services/web-servers/phpfpm/default.nix
+  ./services/web-servers/pomerium.nix
   ./services/web-servers/unit/default.nix
   ./services/web-servers/shellinabox.nix
   ./services/web-servers/tomcat.nix

nixos/modules/services/web-servers/pomerium.nix

@@ -0,0 +1,115 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  format = pkgs.formats.yaml {};
+in
+{
+  options.services.pomerium = {
+    enable = mkEnableOption "the Pomerium authenticating reverse proxy";
+
+    configFile = mkOption {
+      type = with types; nullOr path;
+      default = null;
+      description = "Path to Pomerium config YAML. If set, overrides services.pomerium.settings.";
+    };
+
+    useACMEHost = mkOption {
+      type = with types; nullOr str;
+      default = null;
+      description = ''
+        If set, use a NixOS-generated ACME certificate with the specified name.
+
+        Note that this will require you to use a non-HTTP-based challenge, or
+        disable Pomerium's in-built HTTP redirect server by setting
+        http_redirect_addr to null and use a different HTTP server for serving
+        the challenge response.
+
+        If you're using an HTTP-based challenge, you should use the
+        Pomerium-native autocert option instead.
+      '';
+    };
+
+    settings = mkOption {
+      description = ''
+        The contents of Pomerium's config.yaml, in Nix expressions.
+
+        Specifying configFile will override this in its entirety.
+
+        See <link xlink:href="https://pomerium.io/reference/">the Pomerium
+        configuration reference</link> for more information about what to put
+        here.
+      '';
+      default = {};
+      type = format.type;
+    };
+
+    secretsFile = mkOption {
+      type = with types; nullOr path;
+      default = null;
+      description = ''
+        Path to file containing secrets for Pomerium, in systemd
+        EnvironmentFile format. See the systemd.exec(5) man page.
+      '';
+    };
+  };
+
+  config = let
+    cfg = config.services.pomerium;
+    cfgFile = if cfg.configFile != null then cfg.configFile else (format.generate "pomerium.yaml" cfg.settings);
+  in mkIf cfg.enable ({
+    systemd.services.pomerium = {
+      description = "Pomerium authenticating reverse proxy";
+      wants = [ "network.target" ] ++ (optional (cfg.useACMEHost != null) "acme-finished-${cfg.useACMEHost}.target");
+      after = [ "network.target" ] ++ (optional (cfg.useACMEHost != null) "acme-finished-${cfg.useACMEHost}.target");
+      wantedBy = [ "multi-user.target" ];
+      environment = optionalAttrs (cfg.useACMEHost != null) {
+        CERTIFICATE_FILE = "fullchain.pem";
+        CERTIFICATE_KEY_FILE = "key.pem";
+      };
+      startLimitIntervalSec = 60;
+
+      serviceConfig = {
+        DynamicUser = true;
+        StateDirectory = [ "pomerium" ];
+        ExecStart = "${pkgs.pomerium}/bin/pomerium -config ${cfgFile}";
+
+        PrivateUsers = false;  # breaks CAP_NET_BIND_SERVICE
+        MemoryDenyWriteExecute = false;  # breaks LuaJIT
+
+        NoNewPrivileges = true;
+        PrivateTmp = true;
+        PrivateDevices = true;
+        DevicePolicy = "closed";
+        ProtectSystem = "strict";
+        ProtectHome = true;
+        ProtectControlGroups = true;
+        ProtectKernelModules = true;
+        ProtectKernelTunables = true;
+        ProtectKernelLogs = true;
+        RestrictAddressFamilies = "AF_UNIX AF_INET AF_INET6 AF_NETLINK";
+        RestrictNamespaces = true;
+        RestrictRealtime = true;
+        RestrictSUIDSGID = true;
+        LockPersonality = true;
+        SystemCallArchitectures = "native";
+
+        EnvironmentFile = cfg.secretsFile;
+        AmbientCapabilities = [ "CAP_NET_BIND_SERVICE" ];
+        CapabilityBoundingSet = [ "CAP_NET_BIND_SERVICE" ];
+
+        WorkingDirectory = mkIf (cfg.useACMEHost != null) "$CREDENTIALS_DIRECTORY";
+        LoadCredential = optionals (cfg.useACMEHost != null) [
+          "fullchain.pem:/var/lib/acme/${cfg.useACMEHost}/fullchain.pem"
+          "key.pem:/var/lib/acme/${cfg.useACMEHost}/key.pem"
+        ];
+      };
+    };
+    security.acme.certs = mkIf (cfg.useACMEHost != null) {
+      ${cfg.useACMEHost}.postRun = mkAfter ''
+        /run/current-system/systemd/bin/systemctl -q is-active pomerium.service && /run/current-system/systemd/bin/systemctl restart pomerium.service
+      '';
+    };
+  });
+}