action.yml

name: emulate
description: Emulate unsupported operating systems using QEMU.
inputs:
  operating-system:
    description: The operating-system specifier.
    required: true
runs:
  using: composite
  steps:
  - name: Boot guest ${{ inputs.operating-system }}.
    shell: bash
    working-directory: ${{ runner.temp }}
    env:
      EMULATE_OPERATING_SYSTEM: ${{ inputs.operating-system }}
    run: |
      # Install Vagrant, VirtualBox
      wget -O - https://apt.releases.hashicorp.com/gpg | sudo gpg --dearmor -o /usr/share/keyrings/hashicorp-archive-keyring.gpg
      echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/hashicorp-archive-keyring.gpg] https://apt.releases.hashicorp.com $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/hashicorp.list
      sudo apt-get update --quiet --quiet
      sudo apt-get install --quiet --quiet vagrant virtualbox

      case "$EMULATE_OPERATING_SYSTEM" in
        openbsd-latest) EMULATE_OPERATING_SYSTEM=openbsd-7.6 ;;
        freebsd-latest) EMULATE_OPERATING_SYSTEM=freebsd-14.2 ;;
        netbsd-latest)  EMULATE_OPERATING_SYSTEM=netbsd-10.1 ;;
      esac

      # By default, Vagrant uses the current directory you are in. The working
      # directory is important because it is where Vagrant looks for the Vagrantfile.
      # VAGRANT_CWD can be set to change the working directory to the Vagrantfile.
      VAGRANT_CWD="$GITHUB_ACTION_PATH/$EMULATE_OPERATING_SYSTEM"

      EMULATE_BASH_HIJACKER="$(mktemp)"

      # It's important to delete the BASH_ENV environment variable once we've
      # used it to "hijack" the first bash(1) process, because we don't want to
      # continue hijacking the rest of the process tree.
      cat >"$EMULATE_BASH_HIJACKER" <<EOF
      unset BASH_ENV
      VAGRANT_CWD="$VAGRANT_CWD" exec vagrant ssh < "\$0"
      EOF

      # Set $BASH_ENV to execute our "hijack" script before the BSD commands are
      # executed in an Ubuntu Linux bash process.
      # https://www.gnu.org/software/bash/manual/html_node/Bash-Startup-Files.html
      echo "BASH_ENV=$EMULATE_BASH_HIJACKER" >> "$GITHUB_ENV"

      VAGRANT_CWD="$VAGRANT_CWD" vagrant up