HotFixes

The hotfix release process is used often in software development. Its purpose is to allow critical fixes to be made to the main branch. When a customer finds a critical bug that has to get fixed fast, the hotfix is a good solution.

The hotfix process starts from main, and is merged back into main, but also merged into develop to keep that branch consistent. Once the hotfix mission is completed, it is destroyed as per the following diagram:

====*===*================> main
     \ /
      @====X hotfix
       \
========*================> develop

Here we use a 3 digit versioning system: Major.Minor.Revision, EX: 2.4.5
Develop branch already differs from main by a Major or Minor number

Warning

Do not release a hotfix until QA has tested it.

Preliminaries

First lets get all the version numbers in order. We’ll make bash variables for these.

Assume that develop is already incremented by a Major or Minor revision.
We use the following bash variables to reference our version numbers:

export OLD_PROD=2.2.0 export NEW_PROD=2.2.1 export DEVELOP=2.3.0

Hotfix Workflow

The hotfix process is as follows:

git checkout main
git pull
git checkout -b hofix/$NEW_PROD main
Edit any code that references versions: change $OLD_PROD -> $NEW_PROD
git commit -am “Start $NEW_PROD Hotfix: Version $OLD_PROD -> $NEW_PROD”
Create a PR:
- Squash all small commits for clarity
- Ensure all tests pass
- Ensure QA passes (if any)
Finish the hotfix:
- git checkout main
- git merge –squash hotfix/$NEW_PROD
- git push origin main
- git branch -d hotfix/2.2.1

Using the gh CLI for HOTFIX

The gh command can make the hotfix workflow a bit easier. Here is how:

git checkout -b hotfix/$NEW_PROD main
Make needed changes to your code: version numbers and fixes
git commit -am “Hotfix: Fix critical issue in version $OLD_PROD”

Create a PR (creates pr #1234)

gh pr create  \
   --title "Hotfix: Fix ACME-911 in $OLD_PROD" \
   --base main --head hotfix/$NEW_PROD

   >> Created pull request #1234

Get approval for your pr #1234
gh pr merge 1234

Commit Changes to Hotfix (deprecated):

Here follow a normal defect-fix process but adapted to be based on the hotfix. Once defects are made and hotfix is finished, hotfix will get merged into both main and develop branches. Details ensue:

Make and commit changes needed in $NEW_PROD hotfix
1. git flow feature start ACME-XXX hotfix/$NEW_PROD
2. git flow feature publish
3. work, work, commit & push
4. make pull request from feature/ACME-XXX to hotfix/$NEW_PROD
5. Ensure small commits are squashed: :ref:`squashing_multiple_commits`
6. review and merge
7. git checkout hotfix/$NEW_PROD
8. git pull
9. repeat for all other existing issues
Make sure to clean up all features branches that are merged: Clean Git Repo Branches

Finish Hotfix After all Fixes are Made

Now all hotfix changes are made and you are ready to merge into main (and implicitly, develop).

Warning

QA must test and approve the hotfix branch before you perform the folloing steps. Make sure you have approval before releasing.

UNIT TESTS MUST PASS
QA has tested and approved all defects, or you have higher approval
Update Release section
Update Changes section
git commit -am “Finish $NEW_PROD Hotfix: Version $OLD_PROD -> $NEW_PROD”
git push
git flow hotfix finish $NEW_PROD
- When asked for the tag, use:
  tag $NEW_PROD
On the entry page specify: tag $NEW_PROD
You will be automatically merged into develop
More than likely you will see a merge conflict with setup.py on the develop branch
1. fix the version in setup.py to match $DEVELOP
2. git add setup.py
3. git commit -a # Remove any conflict log entry, assuming you resolved it
4. git push
5. fix any other conflicts, commit, and push
6. git flow hotfix finish $NEW_PROD
git push origin main
git push origin develop
git push –tags

Sanity Check

You should now be in the develop branch. Make sure all branch logs look like what you expect them to be. At the very least, make sure that:

git status on all branches is clean
main logs have the hotfix changes
develop logs have the hotfix changes
The main and develop diff has no hotfix changes:
```
git diff main..develop
```

Here are some other (undocumented) commands that may be useful:

git status
git log –all -p –graph
git diff main –stat
git checkout main
git log –graph
git checkout - # (returns to develop branch)

Build the Master on CICD

If your hotfix process is not automated, you may have to run your CICD process manually. If so, do this now.