Install Dafny

A GitHub Action to download a binary release of Dafny and add it to the system $PATH.

- name: "Install Dafny"
  uses: dafny-lang/setup-dafny-action@v1

If you need to use a specific version:

- name: "Install Dafny"
  uses: dafny-lang/setup-dafny-action@v1
  with:
    dafny-version: "4.9.1"

You can also use nightly-latest to install the most recent nightly pre-release.

This action sets a DAFNY_VERSION environment variable for the benefit of subsequent steps containing the actual resolved Dafny version: particularly useful for nightly-latest!

This action transparently works on macOS by detecting the running OS. You can just set runs-on to a macOS virtual environment like macos-latest.

You can also build Dafny from source, if you want to run against a branch of Dafny still in development:

- name: "Install Dafny"
  uses: dafny-lang/setup-dafny-action@v1
  with:
    dafny-version: "4.9.1"
    build-from-source: support-puppies-and-rainbows

build-from-source can be set to a branch name, tag, commit sha, and so on: anything that actions/checkout understands. Note that dafny-version is still currently required in order to still set the DAFNY_VERSION environment variable, as it is not automatically extracted from the built Dafny.