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Repose and Docker - Tips and Tricks

This is a collection of information cobbled together from several sources, but mostly from sifting through the Official Docker Documentation and then applying it to Repose.

The rest of this assumes you are already familiar with the contents of the Quick Start and Docker recipes. Since you made it here your hunger for Repose Docker knowledge must not have been satiated, so read on and enjoy.

Running Repose as a Docker Container

Basically you just need to:

  1. Acquire a Repose Docker image.

    1. Download a Repose Docker Image.

    2. Build a Repose Docker Image

    3. Building a Repose Docker Image with the build file

  2. Run the Repose Docker image in a Docker container

Building a Repose Docker Image with the build file

The Repose build system expects your Docker Hub credentials to be available at build time. They can be passed in as build properties or the easier way is to add them to your ~/.gradle/gradle.properties file:

  • dockerhub.username=<USERNAME>

  • dockerhub.password=<PASSWORD>

Then try to build a quick Repose Docker image from the root of the Repose project.

./gradlew \
    :repose-aggregator:artifacts:docker:buildUbuntuImageLocal \
    -Prepose-version={project-version}

This will ultimately result in a message similar to:

Successfully built IMAGE_ID
Created image with ID 'IMAGE_ID'.

BUILD SUCCESSFUL

Since this method will not automatically tag the image, you will need to tag it yourself for easier reference later:

docker tag IMAGE_ID local/repose:v{project-version}-ubuntu

Logging inside the Repose Docker Container

The published images adhere to the expectations of Twelve-Factor App logging via streaming everything to STDOUT/STDERR and this is covered further in the Quick Start. Sometimes though, it may be handy to enable the regular Repose Valve logging that is disabled in the published images.

If you are using a published image, then you can execute an interactive session on a running container and uncomment the two AppenderRef lines below in the logging configuration file to begin logging to the standard /var/log/repose/ location inside the container:

/etc/repose/log4j2.xml (partial)
<?xml version="1.0" encoding="UTF-8"?>
<Configuration monitorInterval="15" packages="org.apache.logging.log4j.flume.appender">
      ...
            <AppenderRef ref="RollingFile"/>
      ...
            <AppenderRef ref="PhoneHomeMessages"/>
      ...
</Configuration>

If you are building your own image based on one of the Repose Dockerfile's, then you can simply remove the lines below and the Repose image will log to the standard /var/log/repose/ location.

RUN sed -i 's,<\(Appender.*RollingFile.*/\)>,<!--\1-->,' ${APP_ROOT}/log4j2.xml
RUN sed -i 's,<\(Appender.*PhoneHomeMessages.*/\)>,<!--\1-->,' ${APP_ROOT}/log4j2.xml

The /var/log/repose/ logging directory has also been modified in the Dockerfile to allow logging to be turned on and also support arbitrary user ID’s like are used in the OpenShift environment.

To access the Repose log files, you can mount the directory as a Docker volume when starting the container using a command like the following:

docker run                                   \
   --detach                                  \
   --volume /my/config/directory:/etc/repose \
   --volume /var/log/repose:/var/log/repose  \ (1)
   --publish 8080:8080                       \
   --env JAVA_OPTS=-Xmx1024m                 \
   --name my_repose                          \
   rackerlabs/repose:latest
1 This option defines a volume that is mounted from the host (i.e., the OS running Docker) onto the Docker container. The volume mapping format is HOST_DIRECTORY:CONTAINER_DIRECTORY. So in this case, the contents of /var/log/repose in the container will be available on the host’s /var/log/repose directory. This allows us to tail or persist the logs even if the Docker container is restarted.

If you didn’t recognize it, this is almost identical to the command provided in Using a Repose Docker Image, but with the extra volume mount option.