clouvider-lon01: set up as cache builder

.gitlab-ci.yml

@@ -13,6 +13,8 @@ nixCache:
     - "nix run -f ./ third_party.nixpkgs.bash -c ./hack/populate_secrets.sh"
     - "nix build -v -f ./ci-root.nix --substituters \"https://cache.nixos.org s3://lukegb-nix-cache?endpoint=storage.googleapis.com&trusted=1\""
     - "nix copy -v --to 's3://lukegb-nix-cache?endpoint=storage.googleapis.com' ./result"
+  tags:
+    - cacher
 
 .deploy:
   stage: deploy

ops/nixos/clouvider-lon01/default.nix

@@ -220,5 +220,31 @@ in {
     "d /run/minotarproxy 0700 minotarproxy - -"
   ];
 
+  environment.etc."secrets/gitlab-runner-registration" = {
+    text = ''
+      CI_SERVER_URL=https://hg.lukegb.com
+      REGISTRATION_TOKEN=${depot.ops.secrets.deployer.registrationToken}
+    '';
+    mode = "0600";
+  };
+  services.gitlab-runner = {
+    enable = true;
+    concurrent = 1;
+    services = {
+      deployer = {
+        registrationConfigFile = "/etc/secrets/gitlab-runner-registration";
+        executor = "shell";
+        tagList = [ "cacher" ];
+      };
+    };
+    gracefulTermination = true;
+    gracefulTimeout = "4min";
+    package = depot.nix.pkgs.heptapod-runner;
+  };
+  users.users.gitlab-runner = {
+    createHome = true;
+    home = "/srv/gitlab-runner";
+  };
+
   system.stateVersion = "20.09";
 }