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Base Docker Image for Meteor Apps

This repo contains a base Docker image for use by Meteor apps built using a multistage Dockerfile. You might want to use this base because:

  • You can build/bundle your Meteor app as part of building your Docker image, rather than outside of Docker before the Docker build. This means the machine doing the building need not have Node or Meteor installed, which is important for continuous integration setups; and ensures repeatable builds, since the build environment is isolated and controlled.

  • Using a multistage Dockerfile on your app’s side means that you can publish a much smaller final Docker image that doesn’t have Meteor included, and you can also use an Alpine Linux base which is good for passing security scans (as it presents much less surface area in which scanners might find vulnerabilities).

Quickstart

Step 1: Bootstrap Dockerfile from template

Copy example/default.dockerfile (or example/app-with-native-dependencies.dockerfile if your app has native dependencies that require compilation such as bcrypt, or if your app is using a version of Meteor older than 1.8.1) into the root of your project and rename it Dockerfile. This file assumes that your Meteor app is one level down from the root in a folder named app; either move your app there, or edit Dockerfile to point to your desired path (or the root of your project). Leave Dockerfile at the root.

Step 2: Set the correct Meteor version in the Dockerfile

Edit the Dockerfile you copied into your project, changing the first line so that the numbers at the end match the version of Meteor of your project. You can find your project’s Meteor version in your app’s .meteor/release file.

For example, if your project is running under Meteor 2.7.2:

FROM geoffreybooth/meteor-base:2.7.2

This version must match an available tag from geoffreybooth/meteor-base.

If necessary, update version in the FROM node line to use the Node version appropriate for your release of Meteor. From your application folder, you can get this version via the following command:

docker run --rm geoffreybooth/meteor-base:$(cat ./.meteor/release | cut -c8-99) meteor node --version | cut -c2-99 | grep -o "[0-9\.]*"

Step 3: Configure .dockerignore to speed up builds

Copy example/.dockerignore to your project’s root and edit it appropriately to avoid copying unnecessary files into the Docker context.

Step 4: Build and run

Copy example/docker-compose.yml to your project’s root. Then, from the root of your project, run:

docker-compose up

This builds an image for your app and starts it, along with a linked container for MongoDB. Go to http://localhost/ to see your app running.

Going further

Feel free to edit the Dockerfile you copied into your project, for example to add Linux dependencies. The beauty of the multistage build pattern is that this base image can stay lean, without needing ONBUILD triggers or configuration files for you to influence the image that gets built. You control the final image via your own Dockerfile, so you can do whatever you want.

If you want any command run on startup before the Meteor app itself is run, have your Dockerfile save a file startup.sh into $SCRIPTS_FOLDER. It will be executed automatically by entrypoint.sh.

Why this image, instead of some others?

There are several great Meteor Docker images out there. We built this one because none of the existing open source ones met our needs:

  • jshimko/meteor-launchpad is great, but it’s based on debian:jessie, which fails the security scan we run on all of our Docker images. Debian is also larger than Alpine. This project also always downloads and installs Meteor on every production build, rather than caching it as this base image does.

  • meteor/galaxy-images and Treecom/meteor-alpine both require building the Meteor app in the host machine, before copying the built app into the Docker container. We wanted to avoid needing Node and Meteor installed on our CI servers, and we want the predictability of building within the Docker environment.

Other projects I looked at generally had one or more of the disadvantages cited above. Multistage Docker builds have only been possible since Docker 17.05, which came out in May 2017, and most projects on the Web were designed before then and therefore don’t take advantage of the possibilities offered by a multistage architecture.

Test

# Build all images
./build.sh

# Test all images (requires Node, uses Puppeteer which will download headless Chrome)
./test.sh