Migrate from CircleCI to GitHub Actions (#15)

* Migrate from CircleCI to GitHub Actions

* Adjust if logic

* Test it

* Safer matching + test it further

* Checkout code so we can use the Makefile

* :aff:

* Stop the várzea

.github/workflows/main.yaml

@@ -0,0 +1,87 @@
+name: build_and_push
+
+on:
+  pull_request:
+  push:
+    branches: [master]
+    tags:
+      - 'v[0-9]+.[0-9]+.[0-9]+*'
+
+jobs:
+
+  build_docker:
+    name: Build Docker image
+    runs-on: ubuntu-20.04
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+      - name: Build Docker image and save it to a file
+        run: |
+          DOCKER_REPO=vivareal make docker_image
+          mkdir -p /tmp/docker-cache
+          docker save -o /tmp/docker-cache/x9.tar vivareal/x9:latest
+      - name: Cache Docker image for further jobs in this workflow run
+        uses: actions/upload-artifact@v2
+        with:
+          name: docker-image-cache
+          path: /tmp/docker-cache/
+          retention-days: 1
+
+  push_master_docker:
+    if: github.ref == 'refs/heads/master'
+    name: Push Docker image with tag master
+    needs: build_docker
+    runs-on: ubuntu-20.04
+    env:
+      DOCKER_REPO: vivareal
+      DOCKER_IMAGE_VERSION: master
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+      - name: Download cached Docker image
+        uses: actions/download-artifact@v2
+        with:
+          name: docker-image-cache
+          path: /tmp/docker-cache/
+      - name: Load Docker image and tag it as master
+        run: |
+          docker load < /tmp/docker-cache/x9.tar
+          make docker_tag
+      - uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_PASSWORD }}
+      - name: Push Docker image with tag master
+        run: make docker_push
+
+  push_release_docker:
+    if: "startsWith(github.ref, 'refs/tags/v')"
+    name: Push Docker image according to release
+    needs: build_docker
+    runs-on: ubuntu-20.04
+    env:
+      DOCKER_REPO: vivareal
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+      - name: Download cached Docker image
+        uses: actions/download-artifact@v2
+        with:
+          name: docker-image-cache
+          path: /tmp/docker-cache/
+      - name: Load Docker image and tag it according to current release
+        run: |
+          docker load < /tmp/docker-cache/x9.tar
+          make docker_tag DOCKER_IMAGE_VERSION=${GITHUB_REF#refs/tags/}
+      - uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_PASSWORD }}
+      - name: Push Docker image with release tag
+        run: make docker_push DOCKER_IMAGE_VERSION=${GITHUB_REF#refs/tags/}
+      - name: Push Docker image with latest tag if this version is stable
+        run: |
+          if [[ "${{ github.ref }}" =~ "^refs/tags/v[0-9]+\.[0-9]+\.[0-9]+$" ]]; then
+            make docker_push DOCKER_IMAGE_VERSION=latest
+          fi
+