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whatsthis attempts to identify if the system is running in a container based on a variety of heuristic.



First look for the /.dockerenv file to identify a Docker container. Then look for "docker" inside /proc/cgroups.


Looks for the string "container=" in /proc/environ.


Per a GitHub issue on the podman project page, there is a guarantee that container environment variable will be set to "podman".

The environment variable could be overridden by a user or image creator. As such, this looks for the /run/.containerenv file as well.


Per a GitHub issue on the WSL project page, checking for "microsoft" in either of these two files:

  • /proc/sys/kernel/osrelease
  • /proc/version


For the initial development of the app, platforms were limited to those that could easily be tested. The are some additional container run-times that could be added at a later date:

  • bottlerocket
  • rkt: however, per GitHub page no longer under development
  • openvz: the commercial version, Virtuozzo is available, but otherwise development appears to have ended