A set of environment variables related to pull request to use in CircleCI. These are for GitHub provider

readme.md

How to use it?

1. Put the .sh file anywhere in the repo
2. Inside the job that you want use the variables, in the steps section, add another step like

steps:
  # Create extra env Variables
  - run: cat ./.circleci/scripts/extra-variables.sh >> $BASH_ENV
  - run: echo "base branch -> $BC_PR_BASE_BRANCH"

With that you are able to use it in any following step

circleci-useful-env-variables-pr.sh

# Pull Request ID
export BC_PR_ID="${BC_PR_ID:-${CI_PULL_REQUEST##*/}}";

REPO=$CI_PULL_REQUEST;
REPO=${REPO##https://github.com/};
REPO=${REPO%%/pull/$BC_PR_ID};

# Repo Slug
export BC_REPO_SLUG=$REPO;

# Install dependencies
apk update && apk add jq;

REPOS_VALUES=($(curl -H "Authorization: token $GITHUB_TOKEN" -sSL https://api.github.com/repos/$BC_REPO_SLUG/pulls/$BC_PR_ID | jq -r -c ".head.repo.full_name, .head.repo.owner.login, .base.ref, .head.ref"));

# Pull request base branch (usually master)
export BC_PR_BASE_BRANCH=${REPOS_VALUES[2]};
# Pull request branch (branch to be merged into the base branch)
export BC_PR_BRANCH=${REPOS_VALUES[3]};