Embedded runc issues - Githubissues

I've founds some problems with how runc is embedded.

The embedded runc is copied to a random /tmp file on every build invocation. The PATH is then updated to allow this runc to be used by buildkit.

The following features require runc to be on the path: build, solve, diskusage, prune.

A new runc binary is created in /tmp every time a build is invoked. This is an unexpected and inefficient way to create temp files for the embedded runc. This can be observed simply by watching the /tmp folder grow after successive builds.
When a runc binary is not installed on the system, du and prune do not work. creating worker opt failed: failed to find runc binary This is because only the build command creates the temporary file.
The tests do not pass unless a system runc binary is installed. The travis config installs a separate runc at /usr/bin/runc. https://github.com/genuinetools/img/blob/013bb211567bb92374315affaf0ffa1787fb23c2/.travis.yml#L17

Keep cached versions of the embedded runc in the state directory. Ensure the cached runc is updated when the embedded value changes. Check that the cached runc matches what is embedded.
Instead of only creating tmp file on builds, ensure it exists for all commands as a setup step.
Remove installation of runc as a dependency for tests.

I expect I'll be able to fix these issues and submit a PR, but would like any discussion as I do.

genuinetools / img