Build and push image to dockerhub

.github/workflows/ci.yml

@@ -3,6 +3,7 @@ name: CI
 on:
   push:
   pull_request:
+  workflow_dispatch:
 
 jobs:
   test:
@@ -31,3 +32,27 @@ jobs:
         run: |
           docker compose run --rm -T pricefeed \
             node -e "const { loadConfig } = require('./src/config-loader'); const c = loadConfig(); if (!Array.isArray(c.rpc_nodes) || c.rpc_nodes.length < 3) { console.error('rpc_nodes missing or too few'); process.exit(1); } console.log('docker compose smoke test OK; account =', c.feed_steem_account);"
+
+  docker_push:
+    name: Build and push image to Docker Hub
+    needs: [test, docker]
+    # Publish :latest only from master (or a manual run). Pull requests are
+    # skipped because they cannot access the environment secrets.
+    if: (github.event_name == 'push' && github.ref == 'refs/heads/master') || github.event_name == 'workflow_dispatch'
+    runs-on: ubuntu-latest
+    environment: dockerhub
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_PASSWORD }}
+      - name: Build and push justyy/pricefeed:latest
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          push: true
+          tags: justyy/pricefeed:latest

README.md

@@ -2,6 +2,7 @@
 
 [![CI](https://github.com/DoctorLai/pricefeed/actions/workflows/ci.yml/badge.svg)](https://github.com/DoctorLai/pricefeed/actions/workflows/ci.yml)
 [![Node.js](https://img.shields.io/badge/node-%3E%3D18-43853d?logo=node.js&logoColor=white)](https://nodejs.org/)
+[![Docker Hub](https://img.shields.io/docker/pulls/justyy/pricefeed?logo=docker&logoColor=white)](https://hub.docker.com/r/justyy/pricefeed)
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](LICENSE)
 
 ![image](https://user-images.githubusercontent.com/1764434/173547905-6366f5eb-22dc-4327-bbda-6a4cc4cd3b96.png)
@@ -116,6 +117,26 @@ $ docker run -itd \
     pricefeed
 ```
 
+#### Use the prebuilt image from Docker Hub
+
+A prebuilt image is published to Docker Hub as
+[`justyy/pricefeed`](https://hub.docker.com/r/justyy/pricefeed), so you can skip
+the build step and pull it directly:
+
+```
+$ docker pull justyy/pricefeed:latest
+
+# Edit config.yaml first, then run the container
+$ docker run -itd \
+    --name pricefeed \
+    -v $(pwd)/config.yaml:/app/config.yaml:ro \
+    justyy/pricefeed:latest
+```
+
+The `latest` tag is rebuilt and pushed automatically by CI on every push to the
+`master` branch (see the `docker_push` job in
+[.github/workflows/ci.yml](.github/workflows/ci.yml)).
+
 ### Run with Docker Compose
 
 ```