chore: push docker tags from ci

Adds script and ci config to push to docker hub when
- the master or main branch changes
- semver like tags are pushed to the repo

Pushing a semver like tag pushes a docker image with the same tag. The docker latest tag points to the last semver version tag

Pushing changes to main or master gets you a docker tag of the form <branch name>-<date>-<truncated commit sha>
e.g main-2020-f435621. a <branch>-latest docker tag is provided as a convenince if you really want the bleeding edge. The branch name is included in the docker tag name to make that clearer.

This is a tweak on what I set up for go-ipfs in ipfs/kubo#6949

License: MIT
Signed-off-by: Oli Evans <oli@tableflip.io>

.circleci/config.yml

@@ -4,6 +4,11 @@ executors:
   golang:
     docker:
       - image: cimg/go:1.15.2
+  dockerizer:
+    docker:
+      - image: cimg/go:1.15.2
+    environment:
+      IMAGE_NAME: filecoin/sentinel-visor
 
 jobs:
   test:
@@ -17,19 +22,60 @@ jobs:
       - run: make testshort
 
   docker-build:
-    executor: golang
+    executor: dockerizer
     steps:
       - checkout
       - setup_remote_docker:
           version: "18.09.3"
       - run:
           name: Build Docker image
           command: |
-            docker build -t filecoin/sentinel-visor .
+            docker build -t $IMAGE_NAME .
+      - run:
+          name: Archive Docker image
+          command: docker save -o docker-image.tar $IMAGE_NAME
+      - persist_to_workspace:
+          root: .
+          paths:
+            - ./docker-image.tar
+
+  docker-push:
+    executor: dockerizer
+    steps:
+      - checkout
+      - setup_remote_docker:
+          version: "18.09.3"
+      - attach_workspace:
+          at: /tmp/workspace
+      - run:
+          name: Load archived Docker image
+          command: docker load -i /tmp/workspace/docker-image.tar
+      - run:
+          name: Publish Docker Image to Docker Hub
+          command: |
+            echo "$DOCKERHUB_PASS" | docker login -u "$DOCKERHUB_USERNAME" --password-stdin
+            ./scripts/push-docker-tags.sh "$IMAGE_NAME" "$CIRCLE_SHA1" "$CIRCLE_BRANCH" "$CIRCLE_TAG"
 
 workflows:
   version: 2
   check:
+    # `test` runs for all branches
+    # `docker-build` runs for all branches and tags that look like semver
+    # `docker-push` runs master or main branches and tags that look like semver
+    # see: https://circleci.com/docs/2.0/workflows/#executing-workflows-for-a-git-tag
     jobs:
       - test
-      - docker-build
+      - docker-build:
+          filters:
+            tags:
+              only: /^v[0-9].*/
+      - docker-push:
+          requires:
+            - docker-build
+          filters:
+            branches:
+              only:
+                - master
+                - main
+            tags:
+              only: /^v[0-9].*/

scripts/push-docker-tags.sh

@@ -0,0 +1,68 @@
+#!/usr/bin/env bash
+
+# push-docker-tags.sh
+#
+# Run from ci to tag images based on the current branch or tag name. 
+# Like dockerhub autobuild config, but somewhere we can version control it.
+#
+# The `docker-push` job in .circleci/config.yml runs this script to decide 
+# what tag, if any, to push to dockerhub.
+#
+# Usage:
+#   ./push-docker-tags.sh <image name> <git commit sha1> <git branch name> [git tag name] [dry run]
+#
+# Example:
+#   # dry run. pass a 5th arg to have it print what it would do rather than do it.
+#   ./push-docker-tags.sh myiamge testingsha master "" dryrun
+#    
+#   # push tag for commit on the main branch
+#   ./push-docker-tags.sh myimage testingsha main
+#
+#   # push tag for a new release tag
+#   ./push-docker-tags.sh myimage testingsha release v0.5.0
+#
+#   # serving suggestion in circle ci - https://circleci.com/docs/2.0/env-vars/#built-in-environment-variables
+#   ./push-docker-tags.sh filecoin/sentinel-visor $CIRCLE_SHA1 $CIRCLE_BRANCH $CIRCLE_TAG
+#
+set -euo pipefail
+
+if [[ $# -lt 3 ]] ; then
+  echo 'At least 3 args required. Pass 5 args for a dry run.'
+  echo 'Usage:'
+  echo './push-docker-tags.sh <image name> <git commit sha1> <git branch name> [git tag name] [dry run]'
+  exit 1
+fi
+
+IMAGE_NAME=$1
+GIT_SHA1=$2
+GIT_SHA1_SHORT=$(echo "$GIT_SHA1" | cut -c 1-7)
+GIT_BRANCH=$3
+GIT_TAG=${4:-""}
+DRY_RUN=${5:-false}
+DATE_SHORT=$(date -u +%F)
+
+pushTag () {
+  local IMAGE_TAG=$1
+  if [ "$DRY_RUN" != false ]; then
+    echo "DRY RUN!"
+    echo docker tag "$IMAGE_NAME" "$IMAGE_NAME:$IMAGE_TAG"
+    echo docker push "$IMAGE_NAME:$IMAGE_TAG"
+  else
+    echo "Tagging $IMAGE_NAME:$IMAGE_TAG and pushing to dockerhub"
+    docker tag "$IMAGE_NAME" "$IMAGE_NAME:$IMAGE_TAG"
+    docker push "$IMAGE_NAME:$IMAGE_TAG"
+  fi
+}
+
+if [[ $GIT_TAG =~ ^v[0-9]+ ]]; then
+  pushTag "$GIT_TAG"
+  pushTag "latest"
+
+elif [[ $GIT_BRANCH =~ ^(master|main)$ ]]; then
+  pushTag "$GIT_BRANCH-${DATE_SHORT}-${GIT_SHA1_SHORT}"
+  pushTag "$GIT_BRANCH-latest"
+
+else
+  echo "Nothing to do for branch: $GIT_BRANCH, tag: $GIT_TAG"
+
+fi