broadinstitute/scala-baseimage repository overview

⁠scala-baseimage

This is a base Docker image for Scala applications, specifically web services. Currently this image will have installed:

• Java 8
• Scala 2.11.7
• SBT 0.13.9

This image is build off of baseimage-docker⁠, which provides an init system and process supervisor called runit⁠ for starting and monitoring services.

This image is available on Dockerhub (here⁠)

⁠Usage

It is recommended that the Dockerfile be located in the root of the project source directory. This way, the ADD . /cromwell line below is a good convention for adding the project source code to the Docker container.

Within the project's source tree are two Docker-related files:

• docker/install.sh - A script that is invoked to compile the source code on the container.
• docker/run.sh - A script that is invoked by runit⁠ to start the service. This is optional. If scala-baseimage is not being used to host a server then this can be omitted.

FROM broadinstitute/scala-baseimage

# Cromwell's HTTP Port
EXPOSE 8000

# Current working directory contains the project source code
ADD . /cromwell
RUN ["/bin/bash", "-c", "/cromwell/docker/install.sh /cromwell"]

# Add Cromwell as a service (it will start when the container starts)
RUN mkdir /etc/service/cromwell
ADD docker/run.sh /etc/service/cromwell/run

⁠Using the Docker Container

Run docker build . from this directory to build scala-baseimage. If it is successful, it'll print out the image ID at the end:

$ docker build .
Sending build context to Docker daemon  76.8 kB
Step 0 : FROM phusion/baseimage:0.9.17
 ---> e9f50c1887ea
...
Successfully built a5f889590f04

The container is meant to be run in detached mode (-d flag for docker run). Scala-baseimage has a proper init system as it's PID 1 process, so the container doesn't immediately exit.

To get a Bash shell on the container:

$ docker run -t -i a5f889590f04 bash -l

To run a persistent container:

$ docker run -d a5f889590f04
0623e6ebdfd30d0511b4ee8e56fe32c5d6d99ed436a65b23d1857921822e15f6

To get a Bash shell on the prior persistent container:

$ docker exec -t -i 0623e6ebdfd30d0511b4ee8e56fe32c5d6d99ed436a65b23d1857921822e15f6 bash -l

⁠Using Runit

The PID 1 process will launch Runit which will in turn start all services that are in /etc/service. This can be better visualized by seeing the process tree within the Docker container:

To control the services, use the sv command. The man pages are available from the container but one might have to do apt-get update; apt-get install man to get access to them.

# sv status cromwell
run: cromwell: (pid 17) 147672s
# sv down cromwell
# sv up cromwell