Add a secrets hook

[toolmantim]

This will allow us to keep a list of environment variables that are changed/exported, and then we can filter them from logs and ensure we never send them to Buildkite.

This could also go with a command line flag to add more secrets to the filter… for secrets that are exposed in some other way than the secrets hook?

[JensRantil]

...and https://buildkite.com/docs/agent/securing#using-environment-hooks-for-secrets is not enough for you?

[toolmantim]

Ah, this should have been closed a while ago. It was simply a proof of concept :)