Development Environment with Docker

Setting up and maintaining a proper Opencast build environment can be challenging. The quay.io/opencast/build Docker image, developed by the University of Münster, provides such a build environment already configured and ready to use. In fact, because of Docker's isolation functionality, multiple environments can be operated side by side on a single machine.

Setting up a Docker build environment

Multiple docker-compose files are provided to start up different development environments (see "Testing Locally with Docker" guide in the administration documentation).

Now create a folder where the Opencast repository should be located, and expose its path as an environment variable. You must also create the local Maven repository if it does not already exist.

$ mkdir -p opencast ~/.m2
$ export OPENCAST_SRC=$PWD/opencast

The OPENCAST_SRC variable is used in the compose file to set up a Docker volume so that the host and Docker container can share the Opencast codebase. Similarly, the local Maven repository is shared in order to persist Maven artifacts beyond the lifetime of the Docker container. If you do not want to use the default path ~/.m2 you can set the M2_REPO variable to any other directory on the host system.

Next, you should specify your UID and GID. A matching user will then be created within the container so that all new files can also be accessed from the host. If these variables remain unset, both default to 1000.

$ export OPENCAST_BUILD_USER_UID=$(id -u)
$ export OPENCAST_BUILD_USER_GID=$(id -g)

Single node Opencast Development

Now download the Docker compose file:

$ curl -o docker-compose.yml https://raw.githubusercontent.com/opencast/opencast-docker/<version>/docker-compose/docker-compose.build.yml

With this you are ready to start up the build environment:

$ docker-compose up -d

You can enter the Opencast build environment with the exec command. Omitting the --user opencast-builder argument would give you a root shell, but that is not necessary because the user opencast-builder can use sudo within the container.

$ docker-compose exec --user opencast-builder opencast bash

There are multiple helper scripts available within the container:

# Clone the Opencast source code to the shared volume.
$ oc_clone

# Build Opencast.
$ oc_build

# Install Opencast in the same way as it would be installed in the other Opencast Docker images.
$ oc_install <distribution>

# Run the installed Opencast
$ oc_run

# Uninstall Opencast.
$ oc_uninstall

# Remove all Opencast files (database, media packages, etc.).
$ oc_clean_data

These scripts are provided to automate common tasks, but you can also run the necessary commands directly.

Since the Opencast code is shared, any change from an IDE is directly visible within the container.

Multi-node Opencast Development

Development with multi-node Opencast environments are also supported using a different compose file. Instead of downloading the single-node Docker compose file, download the multi-node version:

$ curl -o docker-compose.yml https://raw.githubusercontent.com/opencast/opencast-docker/<version>/docker-compose/docker-compose.multiserver.build.yml

This file defines a three node (admin, presentation, worker) cluster for use in testing, with all the appropriate ports exported. To access a node run docker-compose exec --user opencast-builder opencast-$nodetype bash. For example, to access the presentation node run docker-compose exec --user opencast-builder opencast-presentation bash.

Available commands are otherwise identical.

Attaching a Remote Debugger to Karaf

By default, the compose file sets the necessary variables to enable remote debugging. The network port is published by the container so that you can connect the remote debugger of your IDE to the port 5005 on localhost. For multi-node setups each node has its debug port exposed: admin lives on 5005, presentation on 5006, and worker on 5007.