Use environment variable in github action if

do it like this:

if: github.ref == 'specific-branch'

reference branch conditional

Though the original problem had been solved without environment vars, I'd like to share how it can be used with if conditions.

jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:

      - name: Set env BRANCH
        run: echo "BRANCH=$(echo $GITHUB_REF | cut -d'/' -f 3)" >> $GITHUB_ENV

      - name: Set env NEED
        run: |
          if [[ $BRANCH == 'master' && $GITHUB_EVENT_NAME == 'push' ]]; then
              echo "NEED=true" >> "$GITHUB_ENV"
          else
              echo "NEED=false" >> "$GITHUB_ENV"
          fi

      - name: Skip Deploy?
        if: env.NEED != 'true'
        run: echo "Only pushing to 'master' causes automatic deployment"

     ...

The first two steps set 2 env variables, the third step demonstrates what syntax you need to follow to use these vars in if conditions.