tdeckers / jimput

Confd but different - reads from stdin

Overview

At times, there's a need to provide a docker container with input that can't be shared through the environment variables. This is the case when the input is large or binary data. jimput was trying to solve this in a complex way, leveraging code from confd.

As it turns out, this can be solved in a much simpler fashion by just piping tarred data into the containers stdin.

• Create input

mkdir tmp
echo "Some text" > tmp/datafile
tar -cf input.tar tmp/datafile

• Pipe the input into the container

ID=$(cat input.tar | docker run -i -a stdin ubuntu /bin/bash -c "tar -x -C / && cat /tmp/datafile")
docker logs $ID

This mechanism allows you to inject multiple data files, config files, etc.. into a container. In a practical example, you'll want to replace the cat /tmp/datafile with the actual command you want your container to run. Very likely you'll want to use exec to ensure the container properly responds to signals (e.g. to stop the container process)