Meta: Add GitHub release action

The action is executed on every tag and creates a GitHub release. The
release contains a .tar.gz asset and a changelog consisting of all
commit messages since the previous tag. Commits with a commit message
starting with "Meta" are excluded from the changelog.

.github/scripts/changelog.sh

@@ -0,0 +1,27 @@
+#!/bin/bash
+
+url=$(git remote get-url origin | sed -r 's/(.*)\.git/\1/')
+
+previous_tag=$(git describe --tags --abbrev=0 HEAD~)
+
+echo "Changes since $previous_tag:"
+echo
+
+# Loop through all commits since previous tag
+for rev in $(git log $previous_tag..HEAD --format="%H" --reverse --no-merges)
+do
+    summary=$(git log $rev~..$rev --format="%s")
+    # Exclude commits starting with "Meta"
+    if [[ $summary != Meta* ]]
+    then
+        # Print markdown list of commit headlines
+        echo "* [$summary]($url/commit/$rev)"
+        # Append commit body indented (blank lines and signoff trailer removed)
+        git log $rev~..$rev --format="%b" | sed '/^\s*$/d' | sed '/^Signed-off-by:/d' | \
+        while read -r line
+        do
+            # Escape markdown formatting symbols _ * `
+            echo "  $line" | sed 's/_/\\_/g' | sed 's/`/\\`/g' | sed 's/\*/\\\*/g'
+        done
+    fi
+done

.github/workflows/ci.yaml

@@ -4,7 +4,13 @@ name: ci
 
 # Controls when the action will run. Triggers the workflow on push or pull request
 # events, but only for the master branch
-on: [push, pull_request]
+on:
+  push:
+    branches:
+      - '**'
+  pull_request:
+    branches:
+      - '**'
 
 # A workflow run is made up of one or more jobs that can run sequentially or in parallel
 jobs:

.github/workflows/release.yaml

@@ -0,0 +1,29 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - '**'
+
+jobs:
+
+  release:
+    runs-on: ubuntu-latest
+    steps:
+
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+
+      - name: Create Package
+        run: tar -czf forgit-${{github.ref_name}}.tar.gz --exclude LICENSE --exclude README.md *
+
+      - name: Generate Changelog
+        run: .github/scripts/changelog.sh > CHANGELOG.md
+
+      - name: Release
+        uses: softprops/action-gh-release@v1
+        with:
+          body_path: CHANGELOG.md
+          files: forgit-${{github.ref_name}}.tar.gz