[ci] Add linter for PR title and body

ci/jenkins/Prepare.groovy.j2

@@ -138,7 +138,7 @@ def should_skip_ci(pr_number) {
   }
   withCredentials([string(
     credentialsId: 'tvm-bot-jenkins-reader',
-    variable: 'TOKEN',
+    variable: 'GITHUB_TOKEN',
     )]) {
     // Exit code of 1 means run full CI (or the script had an error, so run
     // full CI just in case). Exit code of 0 means skip CI.
@@ -151,12 +151,31 @@ def should_skip_ci(pr_number) {
   return git_skip_ci_code == 0
 }
 
+def check_pr(pr_number) {
+  if (env.BRANCH_NAME == null || !env.BRANCH_NAME.startsWith('PR-')) {
+    // never skip CI on build sourced from a branch
+    return false
+  }
+  withCredentials([string(
+    credentialsId: 'tvm-bot-jenkins-reader',
+    variable: 'GITHUB_TOKEN',
+    )]) {
+    sh (
+      script: "python3 ci/scripts/check_pr.py --pr ${pr_number}",
+      label: 'Check PR title and body',
+    )
+  }
+
+}
+
 def prepare() {
   stage('Prepare') {
     node('CPU-SMALL') {
       ws("workspace/exec_${env.EXECUTOR_NUMBER}/tvm/prepare") {
         init_git()
 
+        check_pr(env.CHANGE_ID)
+
         if (env.DETERMINE_DOCKER_IMAGES == 'yes') {
           sh(
             script: "./ci/scripts/determine_docker_images.py {% for image in images %}{{ image.name }}={% raw %}${{% endraw %}{{ image.name }}{% raw %}}{% endraw %} {% endfor %}",

ci/scripts/check_pr.py

@@ -0,0 +1,150 @@
+#!/usr/bin/env python3
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+import argparse
+import re
+import os
+import textwrap
+from dataclasses import dataclass
+from typing import Any, List, Callable
+
+
+from git_utils import GitHubRepo, parse_remote, git
+from cmd_utils import init_log, tags_from_title
+
+
+GITHUB_USERNAME_REGEX = re.compile(r"(@[a-zA-Z0-9-]+)", flags=re.MULTILINE)
+OK = object()
+FAIL = object()
+
+
+@dataclass
+class Check:
+    # check to run, returning OK means it passed, anything else means it failed
+    check: Callable[[str], Any]
+
+    # function to call to generate the error message
+    error_fn: Callable[[Any], str]
+
+
+def non_empty(s: str):
+    if len(s) == 0:
+        return FAIL
+    return OK
+
+
+def usernames(s: str):
+    m = GITHUB_USERNAME_REGEX.findall(s)
+    return m if m else OK
+
+
+def tags(s: str):
+    items = tags_from_title(s)
+    if len(items) == 0:
+        return FAIL
+    return OK
+
+
+def trailing_period(s: str):
+    if s.endswith("."):
+        return FAIL
+    return OK
+
+
+title_checks = [
+    Check(check=non_empty, error_fn=lambda d: "PR must have a title but title was empty"),
+    Check(check=trailing_period, error_fn=lambda d: "PR must not end in a tailing '.'"),
+    # TODO(driazati): enable this check once https://github.com/apache/tvm/issues/12637 is done
+    # Check(
+    #     check=usernames,
+    #     error_fn=lambda d: f"PR title must not tag anyone but found these usernames: {d}",
+    # ),
+]
+body_checks = [
+    Check(check=non_empty, error_fn=lambda d: "PR must have a body but body was empty"),
+    # TODO(driazati): enable this check once https://github.com/apache/tvm/issues/12637 is done
+    # Check(
+    #     check=usernames,
+    #     error_fn=lambda d: f"PR body must not tag anyone but found these usernames: {d}",
+    # ),
+]
+
+
+def run_checks(checks: List[Check], s: str, name: str) -> bool:
+    print(f"Running checks for {name}")
+    print(textwrap.indent(s, prefix="    "))
+    passed = True
+    print("    Checks:")
+    for i, check in enumerate(checks):
+        result = check.check(s)
+        if result == OK:
+            print(f"        [{i+1}] {check.check.__name__}: PASSED")
+        else:
+            passed = False
+            msg = check.error_fn(result)
+            print(f"        [{i+1}] {check.check.__name__}: FAILED: {msg}")
+
+    return passed
+
+
+if __name__ == "__main__":
+    init_log()
+    help = "Check a PR's title and body for conformance to guidelines"
+    parser = argparse.ArgumentParser(description=help)
+    parser.add_argument("--pr", required=True)
+    parser.add_argument("--remote", default="origin", help="ssh remote to parse")
+    parser.add_argument(
+        "--pr-body", help="(testing) PR body to use instead of fetching from GitHub"
+    )
+    parser.add_argument(
+        "--pr-title", help="(testing) PR title to use instead of fetching from GitHub"
+    )
+    args = parser.parse_args()
+
+    try:
+        pr = int(args.pr)
+    except ValueError:
+        print(f"PR was not a number: {args.pr}")
+        exit(0)
+
+    if args.pr_body:
+        body = args.pr_body
+        title = args.pr_title
+    else:
+        remote = git(["config", "--get", f"remote.{args.remote}.url"])
+        user, repo = parse_remote(remote)
+
+        github = GitHubRepo(token=os.environ["GITHUB_TOKEN"], user=user, repo=repo)
+        pr = github.get(f"pulls/{args.pr}")
+        body = pr["body"]
+        title = pr["title"]
+
+    body = body.strip()
+    title = title.strip()
+
+    title_passed = run_checks(checks=title_checks, s=title, name="PR title")
+    print("")
+    body_passed = run_checks(checks=body_checks, s=body, name="PR body")
+
+    if title_passed and body_passed:
+        print("All checks passed!")
+        exit(0)
+    else:
+        print(
+            "Some checks failed, please review the logs above and edit your PR on GitHub accordingly"
+        )
+        exit(1)

ci/scripts/git_skip_ci.py

@@ -46,7 +46,7 @@ def check_pr_title():
         if args.pr_title:
             title = args.pr_title
         else:
-            github = GitHubRepo(token=os.environ["TOKEN"], user=user, repo=repo)
+            github = GitHubRepo(token=os.environ["GITHUB_TOKEN"], user=user, repo=repo)
             pr = github.get(f"pulls/{args.pr}")
             title = pr["title"]
         logging.info(f"pr title: {title}")