docker-clojure
This is the repository for the official Docker image for Clojure. It is automatically pulled and built by Stackbrew into the Docker registry. This image runs on OpenJDK 8 and includes Leiningen, boot or tools-deps (see below for tags and building instructions).
Leiningen vs. boot vs. tools-deps
The version tags on these images look like lein-N.N.N(-alpine), boot-N.N.N(-alpine) and tools-deps(-alpine). These refer to which version of leiningen, boot or tools-deps is packaged in the image (because they can then install and use any version of Clojure at runtime). The default latest (or lein, lein-alpine) images will always have a recent version of leiningen installed. If you want boot, specify either clojure:boot / clojure:boot-alpine or clojure:boot-N.N.N / clojure:boot-N.N.N-alpine. (where N.N.N is the version of boot you want installed). If you want to use tools-deps, specify either clojure:tools-deps or clojure:tools-deps-alpine.
Alpine vs. Debian
In an effort to minimize the size of Docker images, the Docker community is migrating from traditional Linux distributions (like Debian) to the Alpine Linux distribution. It is a very minimal distribution specifically designed for container applications.
The traditional Debian-based Clojure images are still provided under the original tags, but you are encouraged to try running your applications in the new alpine variants. Since Clojure runs on the JVM anyway, chances are everything will just work and you'll save yourself some time and bandwidth.
Examples
Interactive Shell
Run an interactive shell from this image.
docker run -i -t clojure /bin/bash
Then within the shell, create a new Leiningen project and start a Clojure REPL.
lein new hello-world
cd hello-world
lein repl
clojure:onbuild
This image makes building derivative images easier. For most use cases, creating a Dockerfile in the base of your project directory with the line FROM clojure:onbuild will be enough to create a stand-alone image for your project.
clojure:alpine & clojure:alpine-onbuild
These images are based on the minimalist Alpine Linux distribution and are much smaller than the default (Debian-based) images. If your app can run in them, they will be much faster to transfer and take up much less space.
On-build triggers
Build the image
docker build -t clojure:onbuild debian/lein/onbuild
Create a Dockerfile in your Clojure app project
FROM clojure:onbuild
CMD ["lein", "run"]
Put this file in the root of your app.
This image includes multiple ONBUILD triggers which should be all you need to bootstrap most applications. The build will COPY . /usr/src/app and RUN lein deps
You can then build and run the CLojure image:
docker build -t my-clojure-app .
docker run -it --rm --name running-clojure-app my-clojure-app
NOTE: The onbuild image is designed to get you up and running quickly in a development environment. You probably do not want to deploy your applications to production servers using the onbuild image. Compiling an uberjar and running it via java -jar or using lein run trampoline would be much more memory-efficient.
Builds
Except for the onbuild variants, the Dockerfiles are generated from the Dockerfile-lein.template and Dockerfile-boot.template files by the update.sh script.
If you want to modify them (for example, to build in a different version of lein or boot), edit the template(s) and then run ./update.sh. Then the example docker build ... commands below will do what you want.
Note that the update.sh script requires bash version 4+ to run.
If you then want to build all of the non-onbuild images, run the
build-images.sh script. This will tag them as shown in the
examples below. So if you want to push any of them to your own
Docker repo, run something like this after building:
docker tag clojure:lein-2.8.1 my-repo/clojure:lein-2.8.1.
Build examples
Debian-based leiningen
docker build -t clojure:lein-2.8.1 debian/lein
Debian-based boot
docker build -t clojure:boot-2.7.2 debian/boot
Debian-based tools-deps
docker build -t clojure:tools-deps debian/tools-deps
Alpine-based leiningen
docker build -t clojure:lein-2.8.1-alpine alpine/lein
Alpine-based boot
docker build -t clojure:boot-2.7.2-alpine alpine/boot
Alpine-based tools-deps
docker build -t clojure:tools-deps-alpine alpine/tools-deps