git - Automatic tagging of releases

Question

How do you tag your release versions in git?

Now I have each release identified by build number, but they increment even if there are no changes in the repo. My idea is to have it generated automatically on successful deployment on staging server. E.g.

• run Hudson build
• when successful, add new tag, i.e. 1.0-1
• on next successful build add next tag, 1.0-2
• version tag is displayed then in site footer

This would require:

• Hudson to manage next version numbers
• or script to store last tag in some file
• or parse git tags to determine last

Any tips?

Answer 1

I wrote this to help with updating tags incrementally e.g. 1.0.1 to 1.0.2 etc.

2020 update: I have posted an improved version beneath/here. (Also worth seeing @Geoffrey's answer below for some comments on branching).

#!/bin/bash

#get highest tag number
VERSION=`git describe --abbrev=0 --tags`

#replace . with space so can split into an array
VERSION_BITS=(${VERSION//./ })

#get number parts and increase last one by 1
VNUM1=${VERSION_BITS[0]}
VNUM2=${VERSION_BITS[1]}
VNUM3=${VERSION_BITS[2]}
VNUM3=$((VNUM3+1))

#create new tag
NEW_TAG="$VNUM1.$VNUM2.$VNUM3"

echo "Updating $VERSION to $NEW_TAG"

#get current hash and see if it already has a tag
GIT_COMMIT=`git rev-parse HEAD`
NEEDS_TAG=`git describe --contains $GIT_COMMIT 2>/dev/null`

#only tag if no tag already
if [ -z "$NEEDS_TAG" ]; then
    git tag $NEW_TAG
    echo "Tagged with $NEW_TAG"
    git push --tags
else
    echo "Already a tag on this commit"
fi

---

I revisit this 6 years later needing to write a similar script for uploading to npm. Code below or here, comments and suggestions appreciated and welcome:

#!/bin/bash

# https://github.com/unegma/bash-functions/blob/main/update.sh

VERSION=""

#get parameters
while getopts v: flag
do
  case "${flag}" in
    v) VERSION=${OPTARG};;
  esac
done

#get highest tag number, and add 1.0.0 if doesn't exist
CURRENT_VERSION=`git describe --abbrev=0 --tags 2>/dev/null`

if [[ $CURRENT_VERSION == '' ]]
then
  CURRENT_VERSION='1.0.0'
fi
echo "Current Version: $CURRENT_VERSION"


#replace . with space so can split into an array
CURRENT_VERSION_PARTS=(${CURRENT_VERSION//./ })

#get number parts
VNUM1=${CURRENT_VERSION_PARTS[0]}
VNUM2=${CURRENT_VERSION_PARTS[1]}
VNUM3=${CURRENT_VERSION_PARTS[2]}

if [[ $VERSION == 'major' ]]
then
  VNUM1=$((VNUM1+1))
elif [[ $VERSION == 'minor' ]]
then
  VNUM2=$((VNUM2+1))
elif [[ $VERSION == 'patch' ]]
then
  VNUM3=$((VNUM3+1))
else
  echo "No version type (https://semver.org/) or incorrect type specified, try: -v [major, minor, patch]"
  exit 1
fi


#create new tag
NEW_TAG="$VNUM1.$VNUM2.$VNUM3"
echo "($VERSION) updating $CURRENT_VERSION to $NEW_TAG"

#get current hash and see if it already has a tag
GIT_COMMIT=`git rev-parse HEAD`
NEEDS_TAG=`git describe --contains $GIT_COMMIT 2>/dev/null`

#only tag if no tag already
#to publish, need to be logged in to npm, and with clean working directory: `npm login; git stash`
if [ -z "$NEEDS_TAG" ]; then
  npm version $NEW_TAG
  npm publish --access public
  echo "Tagged with $NEW_TAG"
  git push --tags
  git push
else
  echo "Already a tag on this commit"
fi

exit 0

Subnote: this won't work with zsh as (for one), zsh doesn't use 0 indexed arrays.