Docker automated-build providing a minimal Docker image for data container compatible with Docker Compose
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README.md

cogniteev/echo Docker image

Docker automated-build providing a minimal Docker image for data container, compatible with Docker Compose.

Rationale

Data-only container does not need Linux distribution. It just needs an executable to start the container.

tianon/true is the perfect Docker image for that. It provides /true executable and ... that's it!

Unfortunately [Docker Compose][https://github.com/docker/compose] assumes that every container has the /bin/echo executable (see Compose issue #919 on GitHub)

This image is meant to workaround this by providing this missing /bin/echo executable.

Base Docker Image

  • scratch

Image content

  • /bin/echo (written in C, not ASM ... yet)

Installation

  1. Install Docker

  2. Download automated build: docker pull cogniteev/echo

Basic Usage with Docker

  1. Create a data container named data_container:

    sudo docker run -v /data --name data_container cogniteev/echo 
  2. Create a new container that:

    • mounts volume /data of data_container container
    • creates a file named /data/bar
    • is deleted once the container stops
    sudo echo foo |                         \
        docker run                          \
        --volumes-from data_container       \
        -i --rm  busybox                    \
        tee /data/bar
  3. Create a new container that:

    • mounts volume /data of data_container container
    • reads content of file /data/bar
    • is deleted once the container stops
    sudo docker run --volumes-from data_container --rm busybox cat /data/bar