Add a plugin to monitor changes created by cherry-pick-bot

This plugin monitors for new patchsets and integration failures
among changes owned by the cherry-pick-bot.
When a user who is not the original author uploads a new patchset,
this plugin adds the original author or approving reviewer to the
attention set of the bot-owned cherry-pick.
When a bot-owned cherry-pick fails to integrate, the author
of the most recent patchset or of the original change is
added to the attention set.

This updates the current behavior where the cherry-pick-bot
in most cases forgets about a change when it is successfully
staged or has a merge conflict. This behavior has sometimes
resulted in cherry-picks getting lost, as the cherry-pick-bot
becomes the owner of new cherry-pick changes it creates and
the original author is never notified of problems.

Task-number: QTQAINFRA-4611
Change-Id: I3ab61e38aadb31ff5ce0ab7bf0d13b601340890e
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

4 files changed, 199 insertions, 9 deletions

diff --git a/scripts/gerrit/cherry-pick_automation/README.md b/scripts/gerrit/cherry-pick_automation/README.md
index 444542f..eaffb20 100644
--- a/scripts/gerrit/cherry-pick_automation/README.md
+++ b/scripts/gerrit/cherry-pick_automation/README.md
@@ -46,14 +46,6 @@ to restore any in-process items and listeners upon restarting the service.
        conflicts and should not have any direct dependencies on
        any other changes.
 
-
-
-### What this proof-of-concept does NOT (yet) do
-1. This does not currently listen for an automatically staged cherry-pick
-   to pass or fail integration.
-2. Branch validation does not currently verify that the target branch
-   is open to receiving changes.
-
 ### Installation and running
 
 #### Pre-requisites
diff --git a/scripts/gerrit/cherry-pick_automation/notifier.js b/scripts/gerrit/cherry-pick_automation/notifier.js
index cc5993e..598c134 100644
--- a/scripts/gerrit/cherry-pick_automation/notifier.js
+++ b/scripts/gerrit/cherry-pick_automation/notifier.js
@@ -36,7 +36,7 @@ exports.registerCustomListener = registerCustomListener;
 function envOrConfig(ID, configFile) {
   if (process.env[ID]) {
     return process.env[ID];
-  } else if (configFile) {
+  } else if (configFile && fs.existsSync(configFile)) {
     const config = require(configFile);
     return config[ID];
   }
diff --git a/scripts/gerrit/cherry-pick_automation/plugin_bots/integration_monitor/config.json b/scripts/gerrit/cherry-pick_automation/plugin_bots/integration_monitor/config.json
new file mode 100644
index 0000000..6e9b1c7
--- /dev/null
+++ b/scripts/gerrit/cherry-pick_automation/plugin_bots/integration_monitor/config.json
@@ -0,0 +1,3 @@
+{
+    "INTEGRATION_MONITOR_ENABLED" : true
+}
diff --git a/scripts/gerrit/cherry-pick_automation/plugin_bots/integration_monitor/integration_monitor.js b/scripts/gerrit/cherry-pick_automation/plugin_bots/integration_monitor/integration_monitor.js
new file mode 100644
index 0000000..dd6b638
--- /dev/null
+++ b/scripts/gerrit/cherry-pick_automation/plugin_bots/integration_monitor/integration_monitor.js
@@ -0,0 +1,195 @@
+/* eslint-disable no-unused-vars */
+/****************************************************************************
+ **
+ ** Copyright (C) 2022 The Qt Company Ltd.
+ ** Contact: https://www.qt.io/licensing/
+ **
+ ** This file is part of the qtqa module of the Qt Toolkit.
+ **
+ ** $QT_BEGIN_LICENSE:LGPL$
+ ** Commercial License Usage
+ ** Licensees holding valid commercial Qt licenses may use this file in
+ ** accordance with the commercial license agreement provided with the
+ ** Software or, alternatively, in accordance with the terms contained in
+ ** a written agreement between you and The Qt Company. For licensing terms
+ ** and conditions see https://www.qt.io/terms-conditions. For further
+ ** information use the contact form at https://www.qt.io/contact-us.
+ **
+ ** GNU Lesser General Public License Usage
+ ** Alternatively, this file may be used under the terms of the GNU Lesser
+ ** General Public License version 3 as published by the Free Software
+ ** Foundation and appearing in the file LICENSE.LGPL3 included in the
+ ** packaging of this file. Please review the following information to
+ ** ensure the GNU Lesser General Public License version 3 requirements
+ ** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+ **
+ ** GNU General Public License Usage
+ ** Alternatively, this file may be used under the terms of the GNU
+ ** General Public License version 2.0 or (at your option) the GNU General
+ ** Public license version 3 or any later version approved by the KDE Free
+ ** Qt Foundation. The licenses are as published by the Free Software
+ ** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+ ** included in the packaging of this file. Please review the following
+ ** information to ensure the GNU General Public License requirements will
+ ** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+ ** https://www.gnu.org/licenses/gpl-3.0.html.
+ **
+ ** $QT_END_LICENSE$
+ **
+ ****************************************************************************/
+
+exports.id = "integration_monitor";
+
+const gerritTools = require("../../gerritRESTTools");
+
+// This plugin requires no additional config, and relies
+// on the base cherry-pick-bot credentials.
+
+// This plugin listens for failed integrations owned by the cherry-pick
+// bot (The owner of a change is the uploader of the first patch set and cannot
+// be changed). When such a change fails to integrate, this plugin adds
+// the author of the most recent patch set to the attention set and posts
+// a basic message.
+class integration_monitor {
+  constructor(notifier) {
+    this.notifier = notifier;
+    this.logger = notifier.logger;
+    this.retryProcessor = notifier.retryProcessor;
+    this.requestProcessor = notifier.requestProcessor;
+
+    this.handleIntegrationFailed = this.handleIntegrationFailed.bind(this);
+    this.handlePatchsetCreated = this.handlePatchsetCreated.bind(this);
+
+    function pickbotIsOwner(userEmail) {
+      return userEmail == "cherrypick_bot@qt-project.org";
+    }
+
+    notifier.registerCustomListener(notifier.server, "integration_monitor_failed",
+                                    this.handleIntegrationFailed);
+    notifier.server.registerCustomEvent("integration_monitor_failed", "change-integration-fail",
+      function (req) {
+        // The change-integration-fail event doesn't have the patchset author,
+        // so query gerrit for the full change details.
+        gerritTools.queryChange(req.uuid, req.fullChangeID, undefined, undefined,
+          function(success, changeData) {
+            if (success) {
+              let author = changeData.revisions[changeData.current_revision].commit.author.email;
+              let pickbotIsAuthor = author == "cherrypick_bot@qt-project.org";
+              if (pickbotIsOwner(req.change.owner.email) && !pickbotIsAuthor) {
+                // A real user is the author and should be added to the attention set.
+                notifier.server.emit("integration_monitor_failed", req, author);
+              }
+            } else {
+              logger.log(`Failed to query gerrit for ${req.fullChangeID}`, "error", req.uuid);
+            }
+          }
+        );
+      }
+    );
+
+    notifier.registerCustomListener(notifier.server, "integration_monitor_patchset-created",
+                                    this.handlePatchsetCreated);
+    notifier.server.registerCustomEvent("integration_monitor_patchset-created", "patchset-created",
+      function(req) {
+        if (req.change.status == "MERGED")
+          return;  // The CI created a new patchset upon change merge.
+        let uploader = req.uploader.email;
+        let pickbotIsUploader = uploader == "cherrypick_bot@qt-project.org";
+        if (pickbotIsOwner(req.change.owner.email) && !pickbotIsUploader) {
+          // A real user is the uploader and should be added to the attention set.
+          notifier.server.emit("integration_monitor_patchset-created", req, uploader);
+        }
+      }
+    );
+  }
+
+  doAddToAttentionSet(req, user, comment) {
+    let _this = this;
+    gerritTools.addToAttentionSet(
+      req.uuid, req.change, user, undefined,
+      function (success, msg) {
+        // No need to do anything after adding.
+      }
+    );
+  }
+
+  handleIntegrationFailed(req, author) {
+    let _this = this;
+    _this.logger.log(
+      `Received integration failure notification for cherry-picked change ${req.fullChangeID}`,
+      "info", req.uuid
+    );
+    req.change.fullChangeID = req.fullChangeID // Tack on the full change ID so it gets used
+    _this.doAddToAttentionSet(req, author);
+  }
+
+  handlePatchsetCreated(req, uploader) {
+    let _this = this;
+    _this.logger.log(
+      `Received patchset-created by ${uploader} for cherry-picked change ${req.change.project}`,
+      "info", req.uuid
+    );
+
+    // Patchset-created does not include a full change ID. Assemble one.
+    req.fullChangeID = encodeURIComponent(`${req.change.project}~${req.change.branch}~${req.change.id}`);
+    req.change.fullChangeID = req.fullChangeID;
+    // Query the cherry-pick's original branch change to identify the original
+    // author.
+    let ReviewRegex = /^Reviewed-by: .+<(.+)>$/m;
+    let commitMessage = req.change.commitMessage;
+    let originalApprover = undefined;
+    try {
+      originalApprover = commitMessage.match(ReviewRegex)[1];
+    } catch {
+      // Should really never fail, since cherry-picks should always be created
+      // with the original Review footers intact.
+      _this.logger.log(`Failed to locate a reviewer from commit message:\n${commitMessage}`,
+      "error", req.uuid);
+    }
+    if (originalApprover && originalApprover != uploader) {
+      // The approver from the original change should be able to help.
+      gerritTools.setChangeReviewers(req.uuid, req.change.fullChangeID, [originalApprover], undefined,
+        function(){})
+      _this.doAddToAttentionSet(req, originalApprover,
+         `Attention set updated: Added original patch Approver: ${originalApprover}`);
+      return;
+    }
+    // This insane regex is the same as used in the commit message sanitizer,
+    // So it should always find the right footer which references the
+    // picked-from sha.
+    let cherryPickRegex = /^\((?:partial(?:ly)? )?(?:cherry[- ]pick|(?:back-?)?port|adapt)(?:ed)?(?: from| of)?(?: commit)? (\w+\/)?([0-9a-fA-F]{7,40})/m;
+    let originSha = undefined;
+    try{
+      originSha = commitMessage.match(cherryPickRegex)[0];
+    } catch {
+      _this.logger.log(`Failed to match a cherry-pick footer for ${req.change.fullChangeID}`,
+       "error", req.uuid);
+      return // No point in continuing. Log the error and move on.
+    }
+    gerritTools.queryChange(req.uuid, originSha, undefined, undefined,
+      function(success, changeData) {
+        if (success) {
+          let originalAuthor = changeData.revisions[changeData.current_revision].commit.author.email;
+          if (uploader != originalAuthor) {
+            // Add the author of the original change's final patchset to the
+            // attention set of the cherry-pick.
+            gerritTools.setChangeReviewers(req.uuid, req.change.fullChangeID, [originalAuthor],
+              undefined, function(){})
+            _this.doAddToAttentionSet(req, originalAuthor,
+              `Attention set updated: Added original patch author: ${originalAuthor}`);
+          } else {
+            // Now we have a problem. The uploader is the original author, but
+            // they also appear to have self-approved the original patch.
+            // Try to copy all the reviewers from the original change (hopefully there are some).
+            // Adding them as a reviewer will also add them to the attention set.
+            gerritTools.copyChangeReviewers(req.uuid, changeData.id, req.change.fullChangeID);
+          }
+        } else {
+          _this.logger.log(`Failed to query gerrit for ${originSha}`, "error", req.uuid);
+        }
+      }
+    );
+  }
+}
+
+module.exports = integration_monitor;