gerrit: introduce buildbot checks plugin

It's a modified version of @puck's Lix buildbot checks for
gerrit.lix.systems with a slight generalization in the configuration for
many repositories.

Signed-off-by: Raito Bezarius <masterancpp@gmail.com>

services/buildbot/default.nix

@@ -37,6 +37,10 @@ in
     services.nginx.virtualHosts.${cfg.domain} = {
       forceSSL = true;
       enableACME = true;
+      extraConfig = ''
+        add_header Access-Control-Allow-Credentials 'true' always;
+        add_header Access-Control-Allow-Origin 'https://cl.forkos.org' always;
+      '';
     };
 
     services.buildbot-nix.worker = {

services/gerrit/checks.js

@@ -0,0 +1,113 @@
+/* Inspired from the Lix setup.
+ * Original-Author: puckipedia
+ */
+Gerrit.install((plugin) => {
+  // TODO: can we just use `plugin.serverInfo().plugin` and control the settings over there.
+  const configuration = {
+    baseUri: @BASE_URI@,
+    supportedProjects: @SUPPORTED_PROJECTS@,
+  };
+
+  function makeBuildbotUri(suffix) {
+    return `${configuration.baseUri}/${suffix}`;
+  }
+
+  let builders = [];
+  let fetchBuilders = async () => {
+    if (builders.length > 0) return;
+      let data = await (await fetch(makeBuildbotUri(`api/v2/builders`), { credentials: 'include' })).json();
+      builders = data.builders;
+  };
+
+
+  let checksProvider;
+  checksProvider = {
+    async fetch({ repo, patchsetSha, changeNumber, patchsetNumber }, runBefore = false) {
+      if (!configuration.supportedProjects.includes(repo)) {
+        return { responseCode: 'OK' };
+      }
+
+      let num = changeNumber.toString(10);
+
+      let branch = `refs/changes/${num.substr(-2)}/${num}/${patchsetNumber}`;
+
+      let changeFetch = await fetch(makeBuildbotUri(`api/v2/changes?limit=1&order=-changeid&revision=${patchsetSha}&branch=${branch}`), { credentials: 'include' });
+      if (changeFetch.status == 400) {
+        if ((await changeFetch.json()).error === 'invalid origin' && !runBefore) {
+          return await checksProvider.fetch({ repo, patchsetSha, changeNumber, patchsetNumber }, true);
+        }
+
+        return { responseCode: 'OK' };
+      } else if (changeFetch.status === 403) {
+        return { responseCode: 'NOT_LOGGED_IN', loginCallback() {
+          window.open(configuration.baseUri);
+        } };
+      }
+
+      let changes = await changeFetch.json();
+      if (changes.meta.total === 0) {
+        return { responseCode: 'OK' };
+      }
+
+      let { changeid } = changes.changes[0];
+      let { builds } = await (await fetch(makeBuildbotUri(`api/v2/changes/${changeid}/builds?property=owners&property=workername`), { credentials: 'include' })).json();
+      await fetchBuilders();
+      let links = [];
+      let runs = [];
+      for (let build of builds) {
+        let name = `unknown builder ${build.builderid}`;
+        for (let builder of builders) {
+          if (builder.builderid === build.builderid) {
+            name = builder.name;
+            break;
+          }
+        }
+
+        if (name === `${repo}/nix-eval`) {
+            links.push({
+              url: makeBuildbotUri(`#/builders/${build.builderid}/builds/${build.number}`),
+              primary: true,
+              icon: 'external',
+            });
+        }
+
+        let checkrun = {
+          attempt: build.buildrequestid,
+          // FIXME: generalize this accordingly once auto-discovery is available.
+          checkName: name.replace(/^hydraJobs\./, ''),
+          externalId: build.buildrequestid.toString(),
+          status: build.complete ? 'COMPLETED' : (typeof build.started_at !== 'number' ? 'SCHEDULED' : 'RUNNING'),
+          checkLink: makeBuildbotUri(`#/builders/${build.builderid}/builds/${build.number}`),
+          labelName: 'Verified',
+          results: [],
+          links: [{
+            url: makeBuildbotUri(`#/builders/${build.builderid}/builds/${build.number}`),
+            primary: true,
+            icon: 'external',
+          }],
+        };
+
+        if (build.started_at !== null) {
+          checkrun.startedTimestamp = new Date(build.started_at * 1000);
+        }
+
+        if (build.complete_at !== null) {
+          checkrun.finishedTimestamp = new Date(build.complete_at * 1000);
+        }
+
+        if (build.results !== null) {
+          checkrun.results = [{
+            category: build.results < 2 ? 'SUCCESS' : 'ERROR',
+            summary: build.state_string,
+          }];
+        }
+
+        runs.push(checkrun);
+      }
+
+      return { responseCode: 'OK', runs, links };
+    }
+  };
+
+  plugin.checks().register(checksProvider);
+});

services/gerrit/default.nix

@@ -72,6 +72,21 @@ in
       plugins = with pkgs.gerritPlugins; [
         oauth
         metrics-reporter-prometheus
+        # Buildbot checks plugin (writeText because services.gerrit.plugins expects packages)
+        (pkgs.runCommand "checks.js" {
+          BASE_URI = builtins.toJSON "https://buildbot.forkos.org";
+          SUPPORTED_PROJECTS = builtins.toJSON [
+            "infra"
+            "nixpkgs"
+            "buildbot-test"
+          ];
+        }
+        ''
+          echo "configuring buildbot checks plugin for $BASE_URI with $SUPPORTED_PROJECTS project list"
+          substitute ${./checks.js} $out \
+            --replace-fail "@BASE_URI@" "$BASE_URI" \
+            --replace-fail "@SUPPORTED_PROJECTS@" "$SUPPORTED_PROJECTS"
+        '')
       ];
 
       package = pkgs.gerrit;
@@ -126,7 +141,7 @@ in
         # Other settings
         log.jsonLogging = true;
         log.textLogging = false;
-        sshd.advertisedAddress = "${cfg.canonicalDomain}:${cfg.port}";
+        sshd.advertisedAddress = "${cfg.canonicalDomain}:${toString cfg.port}";
         cache.web_sessions.maxAge = "3 months";
         plugins.allowRemoteAdmin = false;
         change.enableAttentionSet = true;