--- id: docker title: Building a Docker image sidebar_label: Docker description: How to build a Backstage Docker image for deployment --- This section describes how to build a Backstage App into a deployable Docker image. It is split into three sections, first covering the host build approach, which is recommended due to its speed and more efficient and often simpler caching. The second section covers a full multi-stage Docker build, and the last section covers how to deploy the frontend and backend as separate images. Something that goes for all of these docker deployment strategies is that they are stateless, so for a production deployment you will want to set up and connect to an external PostgreSQL instance where the backend plugins can store their state, rather than using SQLite. This section assumes that an [app](https://backstage.io/docs/getting-started/create-an-app) has already been created with `@backstage/create-app`, in which the frontend is bundled and served from the backend. This is done using the `@backstage/plugin-app-backend` plugin, which also injects the frontend configuration into the app. This means that you only need to build and deploy a single container in a minimal setup of Backstage. If you wish to separate the serving of the frontend out from the backend, see the [separate frontend](#separate-frontend) topic below. ## Host Build This section describes how to build a Docker image from a Backstage repo with most of the build happening outside of Docker. This is almost always the faster approach, as the build steps tend to execute faster, and it's possible to have more efficient caching of dependencies on the host, where a single change won't bust the entire cache. The required steps in the host build are to install dependencies with `yarn install`, generate type definitions using `yarn tsc`, and build the backend package with `yarn build:backend`. > NOTE: If you created your app prior to 2021-02-18, follow the > [migration step](https://github.com/backstage/backstage/releases/tag/release-2021-02-18) > to move from `backend:build` to `backend:bundle`. In a CI workflow it might look something like this: ```bash yarn install --frozen-lockfile # tsc outputs type definitions to dist-types/ in the repo root, which are then consumed by the build yarn tsc # Build the backend, which bundles it all up into the packages/backend/dist folder. yarn build:backend ``` Once the host build is complete, we are ready to build our image. The following `Dockerfile` is included when creating a new app with `@backstage/create-app`: ```Dockerfile FROM node:16-bullseye-slim # 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 python3 build-essential && \ yarn config set python /usr/bin/python3 # 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 # This switches many Node.js dependencies to production mode. ENV NODE_ENV production # Copy repo skeleton first, to avoid unnecessary docker cache invalidation. # The skeleton contains the package.json of each package in the monorepo, # and along with yarn.lock and the root package.json, that's enough to run yarn install. COPY --chown=node:node yarn.lock package.json packages/backend/dist/skeleton.tar.gz ./ RUN tar xzf skeleton.tar.gz && rm skeleton.tar.gz RUN --mount=type=cache,target=/home/node/.cache/yarn,sharing=locked,uid=1000,gid=1000 \ yarn install --frozen-lockfile --production --network-timeout 300000 # Then copy the rest of the backend bundle, along with any other files we might want. COPY --chown=node:node packages/backend/dist/bundle.tar.gz app-config*.yaml ./ RUN tar xzf bundle.tar.gz && rm bundle.tar.gz CMD ["node", "packages/backend", "--config", "app-config.yaml"] ``` For more details on how the `backend:bundle` command and the `skeleton.tar.gz` file works, see the [`backend:bundle` command docs](../local-dev/cli-commands.md#backendbundle). The `Dockerfile` is located at `packages/backend/Dockerfile`, but needs to be executed with the root of the repo as the build context, in order to get access to the root `yarn.lock` and `package.json`, along with any other files that might be needed, such as `.npmrc`. The `@backstage/create-app` command adds the following `.dockerignore` in the root of the repo to speed up the build by reducing build context size: ```text .git .yarn/cache .yarn/install-state.gz node_modules packages/*/src packages/*/node_modules plugins *.local.yaml ``` With the project built and the `.dockerignore` and `Dockerfile` in place, we are now ready to build the final image. From the root of the repo, execute the build: ```bash docker image build . -f packages/backend/Dockerfile --tag backstage ``` To try out the image locally you can run the following: ```sh docker run -it -p 7007:7007 backstage ``` You should then start to get logs in your terminal, and then you can open your browser at `http://localhost:7007` ## Multi-stage Build > NOTE: The `.dockerignore` is different in this setup, read on for more > details. This section describes how to set up a multi-stage Docker build that builds the entire project within Docker. This is typically slower than a host build, but is sometimes desired because Docker in Docker is not available in the build environment, or due to other requirements. The build is split into three different stages, where the first stage finds all of the `package.json` files that are relevant for the initial install step enabling us to cache the initial `yarn install` that installs all dependencies. The second stage executes the build itself, and is similar to the steps we execute on the host in the host build. The third and final stage then packages it all together into the final image, and is similar to the `Dockerfile` of the host build. The following `Dockerfile` executes the multi-stage build and should be added to the repo root: ```Dockerfile # Stage 1 - Create yarn install skeleton layer FROM node:16-bullseye-slim AS packages WORKDIR /app COPY package.json yarn.lock ./ 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:16-bullseye-slim AS build # install sqlite3 dependencies 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 python3 build-essential && \ yarn config set python /usr/bin/python3 USER node WORKDIR /app COPY --from=packages --chown=node:node /app . # Stop cypress from downloading it's massive binary. ENV CYPRESS_INSTALL_BINARY=0 RUN --mount=type=cache,target=/home/node/.cache/yarn,sharing=locked,uid=1000,gid=1000 \ yarn install --frozen-lockfile --network-timeout 600000 COPY --chown=node:node . . RUN yarn tsc RUN yarn --cwd packages/backend build # If you have not yet migrated to package roles, use the following command instead: # RUN yarn --cwd packages/backend backstage-cli backend:bundle --build-dependencies 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:16-bullseye-slim # 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 python3 build-essential && \ yarn config set python /usr/bin/python3 # 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.lock /app/package.json /app/packages/backend/dist/skeleton/ ./ RUN --mount=type=cache,target=/home/node/.cache/yarn,sharing=locked,uid=1000,gid=1000 \ yarn install --frozen-lockfile --production --network-timeout 600000 # 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 switches many Node.js dependencies to production mode. ENV NODE_ENV production CMD ["node", "packages/backend", "--config", "app-config.yaml"] ``` Note that a newly created Backstage app will typically not have a `plugins/` folder, so you will want to comment that line out. This build also does not work in the main repo, since the `backstage-cli` which is used for the build doesn't end up being properly installed. To speed up the build when not running in a fresh clone of the repo you should set up a `.dockerignore`. This one is different than the host build one, because we want to have access to the source code of all packages for the build. We can however ignore any existing build output or dependencies on the host. For our new `.dockerignore`, replace the contents of your existing one with this: ```text dist-types node_modules packages/*/dist packages/*/node_modules plugins/*/dist plugins/*/node_modules ``` Once you have added both the `Dockerfile` and `.dockerignore` to the root of your project, run the following to build the container under a specified tag. ```sh docker image build -t backstage . ``` To try out the image locally you can run the following: ```sh docker run -it -p 7007:7007 backstage ``` You should then start to get logs in your terminal, and then you can open your browser at `http://localhost:7007` ## Separate Frontend > NOTE: This is an optional step, and you will lose out on the features of the > `@backstage/plugin-app-backend` plugin. Most notably the frontend configuration > will no longer be injected by the backend, you will instead need to use the > correct configuration when building the frontend bundle. It is sometimes desirable to serve the frontend separately from the backend, either from a separate image or for example a static file serving provider. The first step in doing so is to remove the `app-backend` plugin from the backend package, which is done as follows: 1. Delete `packages/backend/src/plugins/app.ts` 2. Remove the following lines from `packages/backend/src/index.ts`: ```tsx import app from './plugins/app'; // ... const appEnv = useHotMemoize(module, () => createEnv('app')); // ... .addRouter('', await app(appEnv)); ``` 3. Remove the `@backstage/plugin-app-backend` and the app package dependency (e.g. `app`) from `packages/backend/packages.json`. If you don't remove the app package dependency the app will still be built and bundled with the backend. Once the `app-backend` is removed from the backend, you can use your favorite static file serving method for serving the frontend. An example of how to set up an NGINX image is available in the [contrib folder in the main repo](https://github.com/backstage/backstage/blob/master/contrib/docker/frontend-with-nginx) Note that if you're building a separate docker build of the frontend you probably need to adjust `.dockerignore` appropriately. Most likely by making sure `packages/app/dist` is not ignored.