Add policy for file ops.

[meowjesty]

• Issue: https://github.com/metalbear-co/private/issues/104
• Related PRs:
  • https://github.com/metalbear-co/operator/pull/729

[aviramha]

What would local do? client will see that and fallback to local?

[meowjesty]

That's a good idea, but not what I had in mind.

I thought that local here would mean that this file has to be read locally, so the operator returns NotFound if the user does not put it under config.fs.local.

Returning a OpenLocal (or something like that) and having mirrord turn this open call into a local one would be neat. Should I do this?