feat(ci): add docker publish job

.github/workflows/docker-publish.yml

@@ -0,0 +1,115 @@
+name: Publish Docker Image
+
+on:
+  push:
+    branches:
+      - master
+    tags:
+      - "*"
+  workflow_dispatch:
+
+concurrency:
+  group: docker-publish-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  resolve:
+    runs-on: ubuntu-latest
+    outputs:
+      should_publish: ${{ steps.publish.outputs.should_publish }}
+      image_tag: ${{ steps.publish.outputs.image_tag }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Resolve publish tag
+        id: publish
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          should_publish=false
+          image_tag=""
+
+          if [[ "${GITHUB_REF_TYPE}" == "branch" && "${GITHUB_REF_NAME}" == "master" ]]; then
+            should_publish=true
+            image_tag="latest"
+          elif [[ "${GITHUB_REF_TYPE}" == "tag" ]]; then
+            should_publish=true
+            image_tag="${GITHUB_REF_NAME}"
+          fi
+
+          echo "should_publish=${should_publish}" >> "${GITHUB_OUTPUT}"
+          echo "image_tag=${image_tag}" >> "${GITHUB_OUTPUT}"
+
+  build:
+    needs: resolve
+    if: needs.resolve.outputs.should_publish == 'true'
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - arch: amd64
+            platform: linux/amd64
+            runner: ubuntu-latest
+          - arch: arm64
+            platform: linux/arm64
+            runner: ubuntu-24.04-arm
+    runs-on: ${{ matrix.runner }}
+    permissions:
+      contents: read
+    steps:
+      - name: Checkout
+        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: blockstream
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Build and push ${{ matrix.arch }}
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: ./Dockerfile
+          platforms: ${{ matrix.platform }}
+          push: true
+          tags: blockstream/waterfalls:${{ needs.resolve.outputs.image_tag }}-${{ matrix.arch }}
+          cache-from: type=gha,scope=waterfalls-${{ matrix.arch }}
+          cache-to: type=gha,mode=max,scope=waterfalls-${{ matrix.arch }}
+
+  manifest:
+    needs:
+      - resolve
+      - build
+    if: needs.resolve.outputs.should_publish == 'true'
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    steps:
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: blockstream
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Create multi-arch manifest
+        shell: bash
+        run: |
+          set -euo pipefail
+          docker buildx imagetools create \
+            -t blockstream/waterfalls:${{ needs.resolve.outputs.image_tag }} \
+            blockstream/waterfalls:${{ needs.resolve.outputs.image_tag }}-amd64 \
+            blockstream/waterfalls:${{ needs.resolve.outputs.image_tag }}-arm64
+
+      - name: Inspect manifest
+        run: docker buildx imagetools inspect blockstream/waterfalls:${{ needs.resolve.outputs.image_tag }}

AGENTS.md

@@ -66,6 +66,7 @@ No `rustfmt.toml` or `clippy.toml` — default settings are used.
 ### Imports
 
 Grouped in this order (separated by blank lines when practical):
+
 1. `std::` — standard library
 2. External crates — `anyhow`, `elements`, `hyper`, `serde`, `tokio`, etc.
 3. `crate::` / `super::` — internal modules
@@ -128,13 +129,38 @@ tests/integration.rs    # Integration tests
 benches/benches.rs      # Criterion benchmarks
 ```
 
-## CI (`.github/workflows/rust.yml`)
+## CI
+
+### Rust checks (`.github/workflows/rust.yml`)
 
 Runs on push/PR to `master`:
+
 - **tests**: downloads bitcoind 28.0 & elementsd 23.2.4, runs `cargo test` and `cargo test -- --ignored`
 - **checks**: `cargo check` with various feature combinations
 - **nix**: `nix build .` with cachix
 
+### Docker publish (`.github/workflows/docker-publish.yml`)
+
+Runs on push to `master`, tag creation, and manual dispatch:
+
+- Push to `master` publishes `blockstream/waterfalls:latest`
+- Tag push publishes `blockstream/waterfalls:<git-tag>`
+
+The workflow builds native images on:
+
+- `ubuntu-latest` for `linux/amd64`
+- `ubuntu-24.04-arm` for `linux/arm64`
+
+Then it creates a multi-arch manifest tag from per-arch tags:
+
+- `blockstream/waterfalls:<final-tag>-amd64`
+- `blockstream/waterfalls:<final-tag>-arm64`
+- `blockstream/waterfalls:<final-tag>` (manifest list with both architectures)
+
+Required GitHub repository secret:
+
+- `DOCKERHUB_TOKEN`
+
 ## Cursor Rules
 
 From `.cursor/rules/my-custom-rule.mdc` (always applied):