Buildkite

1. Create new binary cache on https://app.cachix.org/cache and generate a write auth token.

2. Follow buildkite storing secrets in environment hooks tutorial to set $CACHIX_AUTH_TOKEN.

3. Replace mycache in the following .buildkite/pipeline.yml:

env:
  CACHE_NAME: mycache

steps:
- label: Set up Cachix
    commands:
    - nix-env -iA nixpkgs.cachix
    - cachix use $CACHE_NAME
- wait
- label: Build
    commands:
    - cachix watch-exec $CACHE_NAME nix-build
    - cachix watch-exec $CACHE_NAME -- nix-shell --run "echo nix-shell successfully entered"