Adding a job that checks the PR and commit formats.

This job will make sure that:

    * All commits in a PR were squashed to a single commit
    * The PR title and commit title are identical
    * the PR description and commit message are identical

Signed-off-by: Yoni Bettan <[email protected]>

Author: ybettan

ci/prow/check-commit

@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+
+set -euxo pipefail
+
+#FIXME: check if there is a prow github token that can be use to increase the api rate limit from 60 req/h to 5000 req/h
+
+header='Accept: application/vnd.github+json'
+
+api_call() {
+    res=$(curl -H 'Accept: application/vnd.github+json' https://api.github.com/repos/${REPO_OWNER}/${REPO_NAME}/${1})
+    echo ${res}
+}
+
+get_field_from_json() {
+    echo ${1} | jq ".${2}"
+}
+
+pr=$(api_call pulls/${PULL_NUMBER})
+
+number_of_commits=$(get_field_from_json "${pr}" "commits")
+if [[ ${number_of_commits} != 1 ]]; then
+    echo '
+    All PRs must contain a single commit. Please refer to https://github.com/kubernetes-sigs/kernel-module-management/blob/main/CONTRIBUTING.md
+    '
+    exit 1
+fi
+
+commits=$(api_call pulls/${PULL_NUMBER}/commits)
+
+# The PR title and body are interpreted differently than the commit message in the folowing ways:
+# 1. The PR title and body are different json objects while the commit message is a single json.
+#    - We combine the PR title and body for the comparison.
+#    - We remove quots because we combined multiple strings.
+# 2. PR data is using \r\n for new paragraphs while the commit message is using \n\n.
+#    - We replace all instances of \r\n and \n\n with spaces for the comparison.
+# 3. Those manipulation messes the number of spaces in the strings.
+#    - We trim all the redundant occurences of spaces for the comparison.
+pr_title=$(get_field_from_json "${pr}" "title" | sed 's/"//g' | sed 's/\\r\\n/ /g' | sed 's/ \+/ /g')
+pr_body=$(get_field_from_json "${pr}" "body" | sed 's/"//g' | sed 's/\\r\\n/ /g' | sed 's/ \+/ /g')
+pr_title_and_body="${pr_title} ${pr_body}"
+commit_message=$(get_field_from_json "${commits}" "[].commit.message" | sed 's/"//g' | sed 's/\\n\\n/ /g' | sed 's/\\n/ /g' | sed 's/ \+/ /g')
+
+if [[ "${pr_title_and_body}" != "${commit_message}" ]]; then
+    echo "
+    Commit and PR are out of sync. Make sure the following are identical:
+        * PR title          <-->        commit title
+        * PR description    <-->        commit message
+    "
+
+    echo "
+    PR:
+
+    ${pr_title_and_body}
+
+    Commit:
+
+    ${commit_message}
+    "
+    exit 1
+fi