chore: create a Github release with a changelog for every tag

Fixes #196

.github/workflows/release.yml

@@ -0,0 +1,31 @@
+on:
+  push:
+    tags:
+      - 'v*'
+
+name: Create Release
+
+jobs:
+  build:
+    name: Create Release
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 100
+      - name: Get the version
+        id: version
+        run: echo ::set-output name=tag::${GITHUB_REF:10}
+      - name: Generate change log
+        run: scripts/changelog ${{ steps.version.outputs.tag }} > CHANGELOG.md
+      - name: Create Release
+        uses: actions/create-release@v1
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          tag_name: ${{ github.ref }}
+          release_name: "Release ${{ steps.version.outputs.tag }}"
+          body_path: CHANGELOG.md
+          draft: false
+          prerelease: false

scripts/changelog

@@ -0,0 +1,16 @@
+#!/bin/bash -e
+
+current_tag="$1"
+if [ -z "${current_tag}" ]; then
+  echo "Displays changes since previous tag"
+  echo "Usage: changelog <current tag>"
+  echo "Examples:"
+  echo "  changelog HEAD"
+  echo "  changelog 2.15.0"
+  exit 1
+fi
+
+previous_tag=$(git describe --tags --abbrev=0 "${current_tag}^")
+
+format="- %s ([%h](https://github.com/thumbsup/thumbsup/commit/%h))"
+git log --pretty=format:"${format}" "${previous_tag}".."${current_tag}"