From a7868e4e17a6257b8b82b1714d1493e14e4c5e3f Mon Sep 17 00:00:00 2001
From: Vincent Ambo <mail@tazj.in>
Date: Mon, 17 Aug 2020 22:03:08 +0100
Subject: [PATCH] feat(nixos/clbot): Add ability to post in multiple channels

Adds the ability to post to multiple channels by simply running
multiple instances of clbot.

We should probably implement support for this in clbot itself, but
right now I can't be bothered to write Go.

Change-Id: I5cffd0dc10a7f6cc19c37c5834c5610166b4ae23
Reviewed-on: https://cl.tvl.fyi/c/depot/+/1771
Tested-by: BuildkiteCI
Reviewed-by: kanepyork <rikingcoding@gmail.com>
Reviewed-by: lukegb <lukegb@tvl.fyi>
---
 ops/nixos/clbot.nix          | 49 ++++++++++++++++++++++++++----------
 ops/nixos/whitby/default.nix |  5 ++++
 2 files changed, 41 insertions(+), 13 deletions(-)

diff --git a/ops/nixos/clbot.nix b/ops/nixos/clbot.nix
index adcbebd57..0c45badd2 100644
--- a/ops/nixos/clbot.nix
+++ b/ops/nixos/clbot.nix
@@ -2,26 +2,59 @@
 { config, lib, pkgs, ... }:
 
 let
-  inherit (builtins) concatStringsSep attrValues mapAttrs;
+  inherit (builtins) attrValues concatStringsSep mapAttrs readFile;
+  inherit (pkgs) runCommandNoCC;
+
   inherit (lib)
+    listToAttrs
     mkEnableOption
     mkIf
     mkOption
+    removeSuffix
     types;
 
-  description = "CLBot forwards Gerrit notifications to IRC";
+  description = "Bot to forward CL notifications";
   cfg = config.services.depot.clbot;
 
   mkFlags = flags:
     concatStringsSep " "
       (attrValues (mapAttrs (key: value: "-${key} \"${toString value}\"") flags));
+
+  # Escapes a unit name for use in systemd
+  systemdEscape = name: removeSuffix "\n" (readFile (runCommandNoCC "unit-name" {} ''
+    ${pkgs.systemd}/bin/systemd-escape '${name}' >> $out
+  ''));
+
+  mkUnit = flags: channel: {
+    name = "clbot-${systemdEscape channel}";
+    value = {
+      description = "${description} to ${channel}";
+      wantedBy = [ "multi-user.target" ];
+
+      script = "${config.depot.fun.clbot}/bin/clbot ${mkFlags (cfg.flags // {
+        irc_channel = channel;
+      })} -alsologtostderr";
+
+      serviceConfig = {
+        User = "clbot";
+        EnvironmentFile = "/etc/secrets/clbot";
+        Restart = "always";
+      };
+    };
+  };
 in {
   options.services.depot.clbot = {
     enable = mkEnableOption description;
+
     flags = mkOption {
       type = types.attrsOf types.str;
       description = "Key value pairs for command line flags";
     };
+
+    channels = mkOption {
+      type = with types; listOf str;
+      description = "Channels in which to post (generates one unit per channel)";
+    };
   };
 
   config = mkIf cfg.enable {
@@ -37,16 +70,6 @@ in {
       };
     };
 
-    systemd.services.clbot = {
-      inherit description;
-      script = "${config.depot.fun.clbot}/bin/clbot ${mkFlags cfg.flags} -alsologtostderr";
-      wantedBy = [ "multi-user.target" ];
-
-      serviceConfig = {
-        User = "clbot";
-        EnvironmentFile = "/etc/secrets/clbot";
-        Restart = "always";
-      };
-    };
+    systemd.services = listToAttrs (map (mkUnit cfg.flags) cfg.channels);
   };
 }
diff --git a/ops/nixos/whitby/default.nix b/ops/nixos/whitby/default.nix
index 456dac8a4..c05cb324f 100644
--- a/ops/nixos/whitby/default.nix
+++ b/ops/nixos/whitby/default.nix
@@ -218,6 +218,11 @@ in lib.fix(self: {
       # populated from /etc/secrets/clbot
       irc_pass = "$CLBOT_PASS";
     };
+
+    channels = [
+      "##tvl"
+      "##tvl-dev"
+    ];
   };
 
   services.depot = {