Add circleci config

.circleci/config.yml

@@ -0,0 +1,70 @@
+version: 2.1
+executors:
+  docker-executor:
+    environment:
+      IMAGE_NAME: peterevans/dockerhub-description
+    docker:
+      - image: circleci/buildpack-deps:stretch
+jobs:
+  build:
+    executor: docker-executor
+    steps:
+      - checkout
+      - setup_remote_docker:
+          docker_layer_caching: true
+      - run:
+          name: Build Docker image
+          command: |
+            docker build -t $IMAGE_NAME:latest . --label "org.opencontainers.image.version=${CIRCLE_TAG/v/''}"
+      - run:
+          name: Cache Docker image
+          command: docker save -o image.tar $IMAGE_NAME
+      - persist_to_workspace:
+          root: .
+          paths:
+            - ./image.tar
+  publish-tag:
+    executor: docker-executor
+    steps:
+      - attach_workspace:
+          at: /tmp/workspace
+      - setup_remote_docker
+      - run:
+          name: Load cached Docker image
+          command: docker load -i /tmp/workspace/image.tar
+      - run:
+          name: Publish Docker Image to Docker Hub
+          command: |
+            echo "$DOCKERHUB_PASSWORD" | docker login -u "$DOCKERHUB_USERNAME" --password-stdin
+            IMAGE_TAG=${CIRCLE_TAG/v/''}
+            docker tag $IMAGE_NAME:latest $IMAGE_NAME:$IMAGE_TAG
+            docker push $IMAGE_NAME:latest
+            docker push $IMAGE_NAME:$IMAGE_TAG
+            # If the minor version can be extracted then tag and push
+            MINOR_VERSION=$(echo $CIRCLE_TAG | sed -n "s/^v\([0-9]*.[0-9]*\).[0-9]*$/\1/p")
+            if [[ ${#MINOR_VERSION} -gt 0 ]]; then
+              docker tag $IMAGE_NAME:latest $IMAGE_NAME:$MINOR_VERSION
+              docker push $IMAGE_NAME:$MINOR_VERSION
+            fi
+workflows:
+  version: 2
+  build:
+    jobs:
+      - build
+  build-and-publish-tags:
+    jobs:
+      - build:
+          filters:
+            tags:
+              only: /^v.*/
+            branches:
+              ignore: /.*/
+      - publish-tag:
+          context: org-global
+          requires:
+            - build
+          filters:
+            tags:
+              only: /^v.*/
+            branches:
+              ignore: /.*/