Getting started with Dagger

Install

1. Setup BuildKitd
   • If you have docker installed locally and no BUILDKIT_HOST env var, buildkitd will be started automatically for you when you invoke dagger.
   • Otherwise, you can use the BUILDKIT_HOST env var to point to a running buildkitd. More information here.
2. Build dagger and make sure it's in your PATH
   • go build ./cmd/dagger
   • ln -sf "$(pwd)/dagger" /usr/local/bin
3. (Optional) Setup Docker Credentials
   • If you are receiving HTTP errors while pulling images from DockerHub, you might be getting rate-limited.
   • You can provide credentials to dagger by running docker login on your host and signing into a DockerHub account, which may help avoid these.

Basic Invoking

Simple alpine example:

dagger -p examples/alpine/dagger.json do <<'EOF'
{
  alpine{
    build(pkgs:["curl"]) {
      exec(input: {args:["curl", "https://dagger.io"]}) {
        stdout(lines: 1)
      }
    }
  }
}
EOF

Yarn build (output will just be encoded fs bytes for now, need to add export or shell util to dagger CLI interface):

dagger -p examples/yarn/dagger.json do --local-dir source=. --set runArgs=build

Development

Invoking Actions

With Dagger CLI

TODO: document more, but see Invoking section above for some examples and cmd/dagger/main.go for implementation

With Embedded Go SDK

TODO: document more, but the idea here is that you can also write your own main.go that, similar to cmd/dagger/main.go, calls engine.Start and then do anything you want from there with the full power of Go rather than being limited to the CLI interface of dagger. Eventually, this embedding use case should be possible from any of our supported languages (e.g. Typescript).

Modifying Core

TODO: document, currently just see api/graphql.go for existing core action implementations and schema definition.