@sigHUPster Re-reading your post, I think I understand what’s happening now. You have the repo in /tmp? The Docker snap can read files from within $HOME. If you have the Git repo anywhere within your local user’s $HOME path, it’ll have no problem reading the config file.
Since there hasn’t been a response, I’m going to assume that was the issue. Snaps cannot read from /tmp, only within $HOME. CircleCI Docs has a pending PR to clarify this: https://github.com/circleci/circleci-docs/pull/2113
Yes, looks like you’re right. Not only does the config have to be in $HOME but the snap command must be initiated from there too.
josh@admin:/some/other/path$ circleci config validate -c ~/.circleci/config.yml
Error: open /home/josh/.circleci/config.yml: no such file or directory
josh@admin:/some/other/path$ cd
josh@admin:~$ circleci config validate -c ~/.circleci/config.yml
config file is valid