Buildkite configuration

This contains Terraform configuration for setting up our Buildkite pipelines.

Each pipeline (such as the one for depot itself, or exported subsets of the depot) needs some static configuration stored in Buildkite.

Through //tools/depot-deps a tf-buildkite binary is made available which contains a Terraform binary pre-configured with the correct providers. This is automatically on your $PATH through direnv.

However, secrets still need to be loaded to access the Terraform state and speak to the Buildkite API. These are available to certain users through //ops/secrets.

This can be done with separate direnv configuration, for example:

# //ops/buildkite/.envrc
source_up
eval $(age --decrypt -i ~/.ssh/id_ed25519 $(git rev-parse --show-toplevel)/ops/secrets/tf-buildkite.age)