prepare_release.sh

#!/bin/bash -x
#
# This script:
#   1. parses the version number from the branch name
#   2. updates version.py files to match that version
#   3. iterates through CHANGELOG.md files and updates any files containing
#      unreleased changes
#   4. sets the output variable 'version_updated' to determine whether
#      the github action to create a pull request should run. this allows
#      maintainers to merge changes back into the release branch without
#      triggering unnecessary pull requests
#

VERSION=`echo $1 | awk -F "/" '{print $NF}'`
echo "Using version ${VERSION}"

# check the version matches expected versioning e.g
# 0.6, 0.6b, 0.6b0, 0.6.0
if [[ ! "${VERSION}" =~ ^([0-9])(\.*[0-9]{1,5}[a-b]*){1,3}$ ]]; then
    echo "Version number invalid: $VERSION"
    exit 1
fi

function update_version_file() {
    errors=0
    for f in `find . -name version.py`; do
        # check if version is already in version.py
        grep -q ${VERSION} $f;
        rc=$?
        if [ $rc == 0 ]; then
            errors=1
            echo "${f} already contains ${VERSION}"
            continue
        fi
        # update version.py
        perl -i -pe "s/__version__.*/__version__ = \"${VERSION}\"/g" ${f};
        git add ${f};
        echo "Updating ${f}"
    done
    if [ ${errors} != 0 ]; then
        echo "::set-output name=version_updated::0"
        exit 0
    fi
}

function update_changelog() {
    errors=0
    RELEASE_DATE=`date +%F`
    for f in `find . -name CHANGELOG.md`; do
        # check if version is already in CHANGELOG
        grep -q ${VERSION} $f;
        rc=$?
        if [ $rc == 0 ]; then
            errors=1
            echo "${f} already contains ${VERSION}"
            continue
        fi
        # check if changelog contains any new details
        changes=`sed -n '/## Unreleased/,/^##/p' ${f} | grep -v '^##'  | wc -w | awk '{$1=$1;print}'`
        if [ ${changes} != "0" ]; then
            # update CHANGELOG.md
            perl -i -pe 's/## Unreleased.*/## Unreleased\n\n## '${VERSION}'\n\nReleased '${RELEASE_DATE}'/' ${f};
            git add ${f};
            echo "Updating ${f}"
        else
            echo "Skipping ${f}, no changes detected"
        fi
    done
    if [ ${errors} != 0 ]; then
        echo "::set-output name=version_updated::0"
        exit 0
    fi
}

# create the release branch
git checkout master
git reset --hard origin/master
git checkout -b release/${VERSION}
git push origin release/${VERSION}

# create a temporary branch to create a PR for updated version and changelogs
git checkout -b release/${VERSION}-auto
update_version_file
update_changelog
git commit -m "updating changelogs and version to ${VERSION}"

echo "Time to create a release, here's a sample title:"
echo "[pre-release] Update changelogs, version [${VERSION}]"