GitHub Actions: Notify Go Module Major Version Updates

When Go modules mature and their major version has exceeded one, the
module path requires a version suffix, such as "/v2"[0]. Unfortunately,
the Dependabot is unable to detect such a Go module major version bump
for suffixed major versions[1], resulting in stalling dependencies.

By introducing another GitHub Actions Workflow utilizing gomajor[2],
those major version updates for Go modules can be identified. As a
scheduled workflow, running each Monday morning, it will either create
or update an open GitHub issue with all currently available major
version updates for referenced Go modules.

[0]: https://go.dev/ref/mod#major-version-suffixes
[1]: dependabot/dependabot-core#2213
[2]: https://github.com/icholy/gomajor

.github/workflows/go-mod-major.sh

@@ -0,0 +1,70 @@
+#!/bin/sh
+
+# A GitHub issue with this title and those labels (might be just one)
+# will be created or, if it already exists and is open, will be reused.
+GH_ISSUE_TITLE="Go Module Major Version Updates"
+GH_ISSUE_LABELS="dependencies"
+
+set -eu
+
+# UPDATE_MSG will be altered from within check_updates()
+UPDATE_MSG=""
+
+# check_updates DIR check if any major updates are within DIR.
+# Found updates are being added to UPDATE_MSG
+check_updates() {
+  cd "$1"
+  available_updates="$(gomajor list -major 2>&1 \
+    | grep -v "no module versions found" \
+    | awk '{ print NR ". `" $0 "`" }')"
+  cd - > /dev/null
+
+  if [ -z "$available_updates" ]; then
+    echo "Nothing to do in $1"
+    return
+  fi
+
+  echo "Found $(echo "$available_updates" | wc -l) updates in $1"
+  UPDATE_MSG="$(cat <<EOF
+$UPDATE_MSG
+
+### Updates in \`$1\`
+$available_updates
+
+EOF
+  )"
+}
+
+for DIR in "$@"; do
+  check_updates "$DIR"
+done
+
+if [ -z "$UPDATE_MSG" ]; then
+  echo "Nothing to do at all :-)"
+  exit 0
+fi
+
+UPDATE_MSG="$(cat <<EOF
+## $GH_ISSUE_TITLE
+There are major version updates available for used Go modules.
+
+$UPDATE_MSG
+EOF
+  )"
+
+active_issue="$(gh issue list \
+  --label "$GH_ISSUE_LABELS" \
+  --state "open" \
+  --search "in:title \"$GH_ISSUE_TITLE\"" \
+  --json "number" \
+  --jq ".[0].number")"
+
+if [ -n "$active_issue" ]; then
+  gh issue comment "$active_issue" \
+    --body "$UPDATE_MSG"
+else
+  gh issue create \
+    --title "$GH_ISSUE_TITLE" \
+    --label "$GH_ISSUE_LABELS" \
+    --body "$UPDATE_MSG"
+fi

.github/workflows/go-mod-major.yml

@@ -0,0 +1,25 @@
+name: Go Module Major Update Check
+on:
+  schedule:
+    - cron: '30 6 * * 1' # at 06:30 every Monday morning
+
+jobs:
+  go_mod_update_issue:
+    name: Go Module Major Update Check and Issue Creation
+    runs-on: ubuntu-latest
+
+    permissions:
+      issues: write
+
+    steps:
+    - uses: actions/checkout@v4
+    - uses: actions/setup-go@v5
+      with:
+        go-version: stable
+
+    - run: go install github.com/icholy/gomajor@latest
+
+    - run: ./.github/workflows/go-mod-major.sh "." "tests"
+      env:
+        GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        GH_REPO: ${{ github.repository }}