publish.yml

name: Publish to Crates.io

on:
  push:
    branches: [ main ]
    paths: [ "Cargo.toml" ]
  workflow_dispatch: {}

env:
  CARGO_TERM_COLOR: always

jobs:
  publish:
    name: Pulish to crates.io
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - uses: actions-rs/toolchain@v1
        with:
          toolchain: stable
          override: true
      - name: Cache Cargo
        uses: Swatinem/rust-cache@v1.3.0
      - name: Define Tag and Publish to crates.io
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          CRATES_IO_TOKEN: ${{ secrets.CRATES_IO_TOKEN }}
        run: |
          TAG=v$(cargo metadata --no-deps --quiet | jq -r '.packages[0] | .version')

          git fetch --tags

          if [ $(git tag -l $TAG) ]
          then
            echo "Git tag $TAG already exists; skipping publishing to crates.io."
          else
            git config user.name "Add Tag from CI"
            git config user.email ""
            git tag $TAG
            git push --tags
            
            cargo login $CRATES_IO_TOKEN
            cargo publish
          fi