CI: Add release workflow

This github actions workflow will create a draft release for PRs that
updates the version file.

The commit message subject line must be
Release microcom <version>

The commit message body will be used as release description. The release
is converted from draft to an actual release, and the commit thereby
tagged once the PR is merged.

Signed-off-by: Jonas Rebmann <jre@pengutronix.de>

Author: jonrebm

.github/workflows/build.yml

@@ -1,4 +1,3 @@
----
 name: Build test
 on:
   push:

.github/workflows/do-release-pr.yml

@@ -0,0 +1,33 @@
+name: Publish Release
+
+on:
+  pull_request:
+    types: [closed]
+    paths:
+      - VERSION
+    branches: [main]
+
+permissions:
+  contents: write
+
+jobs:
+  publish-release:
+    if: |
+      github.event.pull_request.merged == true &&
+      contains(github.event.pull_request.labels.*.name, 'release')
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Read version from VERSION
+        id: version
+        run: |
+          ver=$(cat VERSION)
+          echo "version=$ver" >> $GITHUB_OUTPUT
+
+      - name: Publish GitHub Release
+        uses: softprops/action-gh-release@v2
+        with:
+          draft: false
+          tag_name: "v${{ steps.version.outputs.version }}"

.github/workflows/draft-release-pr.yml

@@ -0,0 +1,75 @@
+name: Draft Release
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+    paths:
+      - VERSION
+    branches: [main]
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  validate-release-commit:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout merge
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Get release commit info
+        id: version
+        run: |
+          ver=$(cat VERSION)
+          if ! echo "$ver" | grep -Eq '^[0-9]{4}\.[0-9]{2}\.[0-9]+$'; then
+            echo "Invalid version format: $ver"
+            exit 1
+          fi
+
+          echo "version=$ver" >> $GITHUB_OUTPUT
+
+          headline="$(git show --format=%s ${{github.event.pull_request.head.sha}})"
+          if ! echo "$headline" | grep -Eq "^[Rr]elease microcom $ver$"; then
+            echo "Invalid commit headline: $headline"
+            exit 1
+          fi
+
+          body="$(
+            git show -s --format=%b ${{github.event.pull_request.head.sha}} \
+            | sed -E '/^Signed-off-by: /d'
+          )"
+
+          echo 'body<<EOF' >> $GITHUB_OUTPUT
+          echo "$body" >> $GITHUB_OUTPUT
+          echo 'EOF' >> $GITHUB_OUTPUT
+
+      - name: Install Dependencies
+        run: sudo apt install -y libreadline6-dev autoconf automake
+
+      - name: Build release packages
+        run: |
+          autoreconf -i
+          ./configure
+          make dist
+
+      - name: Create or update release draft
+        uses: softprops/action-gh-release@v2
+        with:
+          draft: true
+          tag_name: v${{steps.version.outputs.version}}
+          name: microcom ${{steps.version.outputs.version}}
+          body: ${{steps.version.outputs.body}}
+          files: |
+            microcom-*.tar.gz
+            microcom-*.tar.xz
+
+      - run: gh pr edit "$NUMBER" --add-label "$LABELS"
+        env:
+          GH_TOKEN: ${{secrets.GITHUB_TOKEN}}
+          GH_REPO: ${{github.repository}}
+          NUMBER: ${{github.event.pull_request.number}}
+          LABELS: release

VERSION

@@ -0,0 +1 @@
+2023.09.0

configure.ac

@@ -1,4 +1,4 @@
-AC_INIT([microcom], [2023.09.0], [oss-tools@pengutronix.de])
+AC_INIT([microcom], [m4_esyscmd_s(cat VERSION)], [oss-tools@pengutronix.de])
 AC_CONFIG_AUX_DIR([build-aux])
 AC_CONFIG_MACRO_DIR([m4])
 AM_INIT_AUTOMAKE([dist-xz])