docker for toolkit documentation: `docker export` not including all layers?

Question

After having given up on other means to document my R analysis environment(s) properely with the aim of analysis reproducibility, I'm setting out, to wrap each individual analysis into a docker container. Here is what I do:

1. Pull the latest rstudio container from the rocker project:

   docker pull rocker/rstudio
   

2. Create a project-specific copy

   docker run -d -p 8787:8787 rocker/rstudio # Produces baseID
   docker commit --message="Snapshot of current rocker/rstudio container" <baseID> rstudio_project.2018
   docker stop <baseID>
   

3. Fire up the container:

   docker run -d -p 8787:8787 -e ROOT=TRUE rstudio_project.2018 # produces ID
   

4. R(Studio)- based project analysis ... finishing with sudo apt-get clean and sudo rm -rf /tmp/*

5. Export a docker image:

   docker export -o docker_rstudio_project.2018.tar <ID>
   xz docker_rstudio_project.2018.tar
   

After having deleted all related containers/images from my local registry, I try to emulate the revisit of the packaged project like so:

1. Import the container:

   docker import docker_rstudio_project.2018.tar.xz rstudio_project.2018.2
   

2. (Try to) Fire up container as was done for the original:

   docker run -d -p 8787:8787 -e ROOT=TRUE rstudio_project.2018.2

I am then faced with the following error:

docker: Error response from daemon: No command specified.

What am I doing wrong? Where did the container loose (what) information on what to start by default?

Answer 1

The export and import commands only handle the file system, not metadata like what command to run. Use save and load instead. See also https://github.com/moby/moby/issues/1826