The goal of this work is to make a human friendly tool for better comparing containers.
We will build a Docker image to calculate pairwise comparisons for some list of containers (including Docker and/or Singularity) and calculate an information coefficient (for similarity) based on the filesystem content. The visualizations and simple metrics are by courtesey of the Singularity Python analysis tools.
We will calculate a similarity matrix to show pairwise, and then link to plots that show each container against the other, specifically highlighting files added, files removed, and files shared. The outputs will be web reports and data files for your use!
docker build -t vanessa/container-diff .
The container-diff image can support comparison between Docker and Singularity containers, in any combination that you like. We do this by way of exporting Singularity containers to .tar.gz, which is installed. Usage looks like any of the following. Note that for all of these, the various extraction tools print out error / warning messages for what I think are symlinked (non existing files) that are attempting to be assessed for a size:
A quick example of the command run to compare a bunch of various operating systems is shown here:
mkdir -p /tmp/web
docker run -v /tmp/web:/data -p 8888:8888 -it vanessa/container-diff centos:6 centos:7
1. Staring extraction for 2 containers.
/data/centos:6-files.json
/data/centos:7-files.json
2. Calculating comparisons
Open browser to http://0.0.0.0:8888
The resulting output files are also saved to /data in the container (mounted at /tmp/web in the example above).
ls /tmp/web/
centos:6-files.json centos:7-to-centos:6.html
centos:6-to-centos:6.html centos:7-to-centos:7.html
centos:6-to-centos:7.html index.html
centos:7-files.json information-coefficient-scores.tsv
If you do this comparison with a Singularity container, this means you can reference
them either with an shub:// or docker:// uri, or a Singularity image mapped to the
container. Here is an example with shub://vsoch/hello-world:
docker run -v /tmp/web:/data --privileged -p 8888:8888 -it vanessa/container-diff centos:6 shub://vsoch/hello-world
I think we also need the privileged tag, at least we did with earlier versions of Singularity.
To generate the example, I ran this command:
docker run -v /tmp/web:/data -p 8888:8888 -it vanessa/container-diff ubuntu:12.04 ubuntu:14.04 ubuntu:16.04 ubuntu:17.04 ubuntu:18.04
Make sure you are in the directory with some web folder - we will map this to our container so the web report (output) and data outputs are persisted on the host.
docker run -v $PWD:/code -v $PWD/web:/data -p 80:80 --entrypoint bash -it vanessa/container-diff