How to generate snapshot tests for build/config/plain.sh?

[cafkafk]

I'm working on a PR adding more of the cgroup metrics to cadvisor (since k8s may e.g. OOM from kernel memory exhaustion without ever reaching memlimits, this is super useful in large production environments).

However, I'm stuck trying to regenerate the snapshot tests that seem to be run through build/config/plain.sh.

It is possible that I'm missing something obvious, but I haven't had any luck so far finding any place describing how to do this.

If someone explains it, I can probably add documentation to docs/development/ in a PR.