This post shows how to build a Backstage app image (a single container image that runs the Backstage backend and serves the built frontend), tag it with a short Git commit SHA (7 chars like 3c71ccc), and push it to Harbor using a system robot account.
Target image format:
- harbor.maksonlee.com/backstage/homelab-backstage:<short-sha>
What you’ll build
- Jenkins pipeline triggered by GitHub push
- Docker BuildKit enabled
- Multi-stage Docker build (build happens inside Docker)
- Tag images with short SHA (
git rev-parse --short=7 HEAD) - Push to Harbor using a Harbor system robot (
robot$jenkins) stored as Jenkins credentials
Prerequisites
Jenkins agent requirements
Your Jenkins agent labeled ssh-agent-with-docker must have:
- Docker installed and usable by the Jenkins user
- Network access to
harbor.maksonlee.com - If Harbor uses a private CA certificate, Docker must trust it (see Troubleshooting)
Backstage repository
Your Backstage repo root should contain:
.yarn/,.yarnrc.yml,yarn.lockpackages/(and optionallyplugins/)- runtime configs such as
app-config.yamlandapp-config.production.yaml
- Add the multi-stage Dockerfile
Create Dockerfile.multi in the repo root.
This Dockerfile builds your Backstage app inside Docker:
- installs dependencies with Yarn
- compiles TypeScript
- builds the backend bundle
- produces a runtime image with production dependencies only
Dockerfile.multi
# Stage 1 - Create yarn install skeleton layer
FROM node:22-bookworm-slim AS packages
WORKDIR /app
COPY backstage.json package.json yarn.lock ./
COPY .yarn ./.yarn
COPY .yarnrc.yml ./
COPY packages packages
# Comment this out if you don't have any internal plugins
COPY plugins plugins
RUN find packages \! -name "package.json" -mindepth 2 -maxdepth 2 -exec rm -rf {} \+
# Stage 2 - Install dependencies and build packages
FROM node:22-bookworm-slim AS build
# Set Python interpreter for `node-gyp` to use
ENV PYTHON=/usr/bin/python3
# Install isolate-vm dependencies, these are needed by the @backstage/plugin-scaffolder-backend.
RUN --mount=type=cache,target=/var/cache/apt,sharing=locked \
--mount=type=cache,target=/var/lib/apt,sharing=locked \
apt-get update && \
apt-get install -y --no-install-recommends python3 g++ build-essential && \
rm -rf /var/lib/apt/lists/*
# Install sqlite3 dependencies. You can skip this if you don't use sqlite3 in the image,
# in which case you should also move better-sqlite3 to "devDependencies" in package.json.
RUN --mount=type=cache,target=/var/cache/apt,sharing=locked \
--mount=type=cache,target=/var/lib/apt,sharing=locked \
apt-get update && \
apt-get install -y --no-install-recommends libsqlite3-dev && \
rm -rf /var/lib/apt/lists/*
USER node
WORKDIR /app
COPY --from=packages --chown=node:node /app .
RUN --mount=type=cache,target=/home/node/.cache/yarn,sharing=locked,uid=1000,gid=1000 \
yarn install --immutable
COPY --chown=node:node . .
RUN yarn tsc
RUN yarn --cwd packages/backend build
RUN mkdir packages/backend/dist/skeleton packages/backend/dist/bundle \
&& tar xzf packages/backend/dist/skeleton.tar.gz -C packages/backend/dist/skeleton \
&& tar xzf packages/backend/dist/bundle.tar.gz -C packages/backend/dist/bundle
# Stage 3 - Build the actual backend image and install production dependencies
FROM node:22-bookworm-slim
# Set Python interpreter for `node-gyp` to use
ENV PYTHON=/usr/bin/python3
# Install isolate-vm dependencies, these are needed by the @backstage/plugin-scaffolder-backend.
RUN --mount=type=cache,target=/var/cache/apt,sharing=locked \
--mount=type=cache,target=/var/lib/apt,sharing=locked \
apt-get update && \
apt-get install -y --no-install-recommends python3 g++ build-essential && \
rm -rf /var/lib/apt/lists/*
# Install sqlite3 dependencies. You can skip this if you don't use sqlite3 in the image,
# in which case you should also move better-sqlite3 to "devDependencies" in package.json.
RUN --mount=type=cache,target=/var/cache/apt,sharing=locked \
--mount=type=cache,target=/var/lib/apt,sharing=locked \
apt-get update && \
apt-get install -y --no-install-recommends libsqlite3-dev && \
rm -rf /var/lib/apt/lists/*
# From here on we use the least-privileged `node` user to run the backend.
USER node
# This should create the app dir as `node`.
# If it is instead created as `root` then the `tar` command below will
# fail: `can't create directory 'packages/': Permission denied`.
# If this occurs, then ensure BuildKit is enabled (`DOCKER_BUILDKIT=1`)
# so the app dir is correctly created as `node`.
WORKDIR /app
# Copy the install dependencies from the build stage and context
COPY --from=build --chown=node:node /app/.yarn ./.yarn
COPY --from=build --chown=node:node /app/.yarnrc.yml ./
COPY --from=build --chown=node:node /app/backstage.json ./
COPY --from=build --chown=node:node /app/yarn.lock /app/package.json /app/packages/backend/dist/skeleton/ ./
# Note: The skeleton bundle only includes package.json files -- if your app has
# plugins that define a `bin` export, the bin files need to be copied as well to
# be linked in node_modules/.bin during yarn install.
RUN --mount=type=cache,target=/home/node/.cache/yarn,sharing=locked,uid=1000,gid=1000 \
yarn workspaces focus --all --production && rm -rf "$(yarn cache clean)"
# Copy the built packages from the build stage
COPY --from=build --chown=node:node /app/packages/backend/dist/bundle/ ./
# Copy any other files that we need at runtime
COPY --chown=node:node app-config*.yaml ./
# This will include the examples, if you don't need these simply remove this line
COPY --chown=node:node examples ./examples
# This switches many Node.js dependencies to production mode.
ENV NODE_ENV=production
# This disables node snapshot for Node 20 to work with the Scaffolder
ENV NODE_OPTIONS="--no-node-snapshot"
CMD ["node", "packages/backend", "--config", "app-config.yaml", "--config", "app-config.production.yaml"]
- Add a Dockerfile-specific ignore file
If your existing .dockerignore is optimized for host-build (for example it ignores packages/*/src or ignores plugins/), it will break multi-stage builds.
Create Dockerfile.multi.dockerignore in repo root:
dist-types
node_modules
packages/*/dist
packages/*/node_modules
plugins/*/dist
plugins/*/node_modules
*.local.yaml
This keeps the build context clean while still including all source code required by the multi-stage build.
- Create a Harbor system robot account for Jenkins
In Harbor UI (system admin):
- Administration → Robot Accounts → New Robot Account
- Choose System robot account
- Name it:
jenkins
Harbor login user becomes:robot$jenkins - System permissions: none
- Project permissions: for the project you will push to (example:
backstage), grant:- Repository → Pull
- Repository → Push
- Create the account and copy the secret/token (shown once)
- Add the robot credentials to Jenkins
Jenkins → Manage Jenkins → Credentials → System → Global credentials → Add Credentials:
- Kind: Username with password
- Username:
robot$jenkins - Password:
<robot secret/token> - ID:
harbor-system-robot - Description:
Harbor system robot for pushing Backstage images
Click Create.
- Jenkinsfile: build and push with short SHA tags
pipeline {
agent { label 'ssh-agent-with-docker' }
triggers {
githubPush()
}
environment {
DOCKER_BUILDKIT = '1'
HARBOR_REGISTRY = 'harbor.maksonlee.com'
HARBOR_PROJECT = 'backstage'
IMAGE_NAME = 'homelab-backstage'
}
stages {
stage('Fetch code') {
steps {
deleteDir()
git credentialsId: 'vault-github-ssh',
url: 'git@github.com:maksonlee/homelab-backstage.git',
branch: 'main'
}
}
stage('Build') {
steps {
sh '''#!/usr/bin/env bash
set -euo pipefail
TAG="$(git rev-parse --short=7 HEAD)"
IMAGE_SHA="${HARBOR_REGISTRY}/${HARBOR_PROJECT}/${IMAGE_NAME}:${TAG}"
IMAGE_TEST="${HARBOR_REGISTRY}/${HARBOR_PROJECT}/${IMAGE_NAME}:test"
docker build -f Dockerfile.multi -t "$IMAGE_SHA" -t "$IMAGE_TEST" .
'''
}
}
stage('Push to Harbor') {
steps {
withCredentials([usernamePassword(
credentialsId: 'harbor-system-robot',
usernameVariable: 'HARBOR_USER',
passwordVariable: 'HARBOR_PASS'
)]) {
sh '''#!/usr/bin/env bash
set -euo pipefail
TAG="$(git rev-parse --short=7 HEAD)"
IMAGE_SHA="${HARBOR_REGISTRY}/${HARBOR_PROJECT}/${IMAGE_NAME}:${TAG}"
IMAGE_TEST="${HARBOR_REGISTRY}/${HARBOR_PROJECT}/${IMAGE_NAME}:test"
echo "$HARBOR_PASS" | docker login "$HARBOR_REGISTRY" -u "$HARBOR_USER" --password-stdin
docker push "$IMAGE_SHA"
docker push "$IMAGE_TEST"
docker logout "$HARBOR_REGISTRY"
'''
}
}
}
}
post {
always {
cleanWs(deleteDirs: true, notFailBuild: true)
}
}
}
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