feat(ops/nixos): Add a module for hound r/854

This module sets up hound, a generic code search engine.

1 files changed, 62 insertions, 0 deletions

diff --git a/ops/nixos/modules/hound.nix b/ops/nixos/modules/hound.nix
new file mode 100644
index 000000000000..690055bde3b6
--- /dev/null
+++ b/ops/nixos/modules/hound.nix
@@ -0,0 +1,62 @@
+# This module serves hound.
+#
+# https://github.com/hound-search/hound
+{ pkgs, config, lib, ... }:
+
+let
+  cfg = config.services.depot.hound;
+  configJson = with builtins; toFile "config.json" (toJSON {
+    inherit (cfg) title repos;
+    max-concurrent-indexers = cfg.maxConcurrentIndexers;
+    dbpath = "/var/lib/hound";
+    health-check-uri = "/healthz";
+  });
+in {
+  options.services.depot.hound = with lib; {
+    enable = mkOption {
+      type        = types.bool;
+      default     = false;
+      description = ''
+        Whether to enable the hound code search engine to forward
+        journald logs to Stackdriver Logging.
+      '';
+    };
+
+    repos = mkOption {
+      type = lib.types.attrs;
+      description = "Repository configuration for hound.";
+    };
+
+    port = mkOption {
+      type = lib.types.int;
+      default = 6080;
+      description = "The port hound should listen on.";
+    };
+
+    title = mkOption {
+      type = lib.types.str;
+      description = "Page title for this hound instance";
+    };
+
+    maxConcurrentIndexers = mkOption {
+      type = lib.types.int;
+      default = 2;
+    };
+  };
+
+  config = {
+    systemd.services.hound = {
+      description = "Code search engine";
+      script = "${config.depot.third_party.hound}/bin/houndd -addr ':${toString cfg.port}' -conf '${configJson}'";
+      wantedBy = [ "multi-user.target" ];
+      path = [ pkgs.git ];
+
+      serviceConfig = {
+        Restart = "always";
+        DynamicUser = true;
+        StateDirectory = "hound";
+        SupplementaryGroups = "git";
+      };
+    };
+  };
+}