Bash script to auto-generate versioning information based on Git history

repo_version.sh

#!/bin/bash

# This script determines a version string and a deployment target based on Git history
#
# Returns: VERSION DEPLOYMENT_TARGET
# where DEPLOYMENT_TARGET is [prod|stage|dev|'']

branch=$(git rev-parse --abbrev-ref HEAD)
tag=$(git describe --tags --exact-match 2>/dev/null)

# if on master, require an explicit tag
# version will be the tag
if [[ $branch == master ]]; then
  if [ -z "$tag" ]; then
    echo "ERROR: Untagged master branch" >>/dev/stderr
    exit 1
  fi
  echo $tag prod

# if on a release/X branch, forbid explicit tags
# version will be X-betaN
elif [[ $branch == release/* ]]; then
  if [ -n "$tag" ]; then
    echo "ERROR: Explicitly tagged commit ${tag} in branch ${branch}" >>/dev/stderr
    exit 1
  fi
  after_the_slash=${branch#*/}
  base=$(git merge-base -a HEAD develop)
  count=$(git rev-list --count HEAD ^${base})
  echo ${after_the_slash}-beta${count} stage

# if on a hotfix branch, forbid explicit tags
# anything after "hotfix" in the branch name will be ignored
# version will be $last_tag-hotfixN
elif [[ $branch == hotfix* ]]; then
  if [ -n "$tag" ]; then
    echo "ERROR: Explicitly tagged commit ${tag} in branch ${branch}" >>/dev/stderr
    exit 1
  fi
  last_tag=$(git describe --abbrev=0 2>/dev/null)
  if [ -z "$last_tag" ]; then
    echo "ERROR: No tag found in history of ${branch}" >>/dev/stderr
    exit 1
  fi
  count=$(git rev-list --count HEAD ^${last_tag})
  echo ${last_tag}-hotfix${count} stage

# if on the devel/develop branch, allow explicit tags
# version will be either $devel-$tag
# or in the format $devel-YYMMDD-HASH
elif [[ $branch == devel* ]]; then
  if [ -z "$tag" ]; then
    ver=$(git log -1 --pretty='%cd-%h' --date=format:'%y%m%d')
  else
    ver=$tag
  fi
  echo devel-${ver} dev

# in any other branch, allow explicit tags
# version will be either $branch-$tag
# or in the format $branch-YYMMDD-HASH
else
  if [ -z "$tag" ]; then
    ver=$(git log -1 --pretty='%cd-%h' --date=format:'%y%m%d')
  else
    ver=$tag
  fi
  echo "WARNING: No deployment target for ${branch}" >>/dev/stderr
  echo ${branch}-${ver}
fi