Merlin has a simple Dockerfile description for running a container with all requirements installed.

Build the container

The docker container can be built by building in the top level merlin directory.

docker build -t merlin .

This will create a merlin:latest image in your docker image collection with a user “merlinu” and a WORKDIR set to /home/merlinu.

docker images

Run the container

The container can be run in detached mode to provide both the merlin and celery commands

docker run --rm -td --name my-merlin merlin
alias merlin="docker exec my-merlin merlin"
alias celery="docker exec my-merlin celery"

Examples can be run through docker containers by first starting a server for the broker and backend. The server can be a redis or rabbitmq , for this demonstration a redis server will be used. The backend will always be a redis server.

docker pull redis
docker run -d -p 6379:6379 --name my-redis redis

A local output directory can be defined by using the --volume docker arguments. It is recommended that a fixed directory be used for the --volume argument. The merlin docker container is linked to the redis server above by using the --link option.

# Create local working directory
mkdir $HOME/merlinu
cd $HOME/merlinu

docker pull llnl/merlin
docker run --rm -td --name my-merlin --link my-redis --volume "$HOME/merlinu":/home/merlinu llnl/merlin

alias merlin="docker exec my-merlin merlin"
alias celery="docker exec my-merlin celery"

# Create the $HOME/merlinu/.merlin/app.yaml using redis
merlin config --broker redis

<edit $HOME/merlinu/.merlin/app.yaml and change the broker and backend server: variables to  my-redis>

# Copy an example to the local dir
merlin example feature_demo

# Run a test run without workers
merlin run feature_demo/feature_demo.yaml --dry --local

# Define the tasks and load them on the broker
merlin run feature_demo/feature_demo.yaml

# Start workers to pull tasks from the server and run them in the container
merlin run-workers feature_demo/feature_demo.yaml

A shell can started in the container by using the --entrypoint command. If the user would like to examine the container contents, they can use a shell as the entry point.

docker run --rm -ti --volume "$HOME/merlinu":/home/merlinu --entrypoint="/bin/bash" merlin