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Software Development Notes

Git Hook to Add Issue Number to Commit Message

When using a project management system (Jira, Redmine, GitHub issues, etc.), it is useful to add the issue number to the commit message. This makes it easier to understand which issue the commit belongs to and often allows the project management system to display related commits.

For the same reasons, it is also useful to include the issue number in the branch name, such as 123-branch-description or feature/PROJECT-123-branch-description.

The process of adding the issue number to the commit message can be automated with the git prepare-commit-msg hook (shell script).

Below are a few examples of hook scripts.

Branch Named as 123-branch-description

In the simplest case, we have branches named as 123-branch-description, where 123 is the issue id: 

#!/bin/bash

# This hook works for branches named such as "123-description" and will add "[#123]" to the commit message.

# get current branch
branchName=`git rev-parse --abbrev-ref HEAD`

# search for the issue id in the branch name, such as "123-description" or "XXX-123-description"
issueId=$(echo $branchName | sed -nE 's,([A-Z]?-?[0-9]+)-.+,\1,p')

# only prepare commit message if pattern matched and issue id was found
if [[ ! -z $issueId ]]; then
 # $1 is the name of the file containing the commit message
 # sed -i.bak -e "1s/^/\n\n[$issueId]\n/" $1
 echo -e "[#$issueId] ""$(cat $1)" > "$1"
 # echo -e "[$issueId]\n""$(cat $1)" > "$1"
 # sed -i.bak -e "1s/^/$TRIMMED /" $1
fi

Branch Named as feature/PROJECT-123-branch-description

This version is useful for gitflow and Jira (where we should use the PROJECT-123 format to display commits in the issue): 

#!/bin/bash

# This hook works for branches named such as "feature/ABC-123-description" and will add "[ABC-123]" to the commit message.

# get current branch
branchName=`git rev-parse --abbrev-ref HEAD`

# search for the Jira issue id in a pattern such as "feature/ABC-123-description"
jiraId=$(echo $branchName | sed -nE 's,[a-z]+/([A-Z]+-[0-9]+)-.+,\1,p')

# only prepare commit message if pattern matched and jiraId was found
if [[ ! -z $jiraId ]]; then
 # $1 is the name of the file containing the commit message
 # sed -i.bak -e "1s/^/\n\n[$jiraId]\n/" $1
 echo -e "[$jiraId] ""$(cat $1)" > "$1"
 # echo -e "[$jiraId]\n""$(cat $1)" > "$1"
 # sed -i.bak -e "1s/^/$TRIMMED /" $1
fi

Cross-Repository Version

This is useful when a project uses multiple repositories on GitHub and issues are tracked in one of the repositories (or there is a separate project for issues).

In this case, we also need to add the full repository name to the commit message.

The hook below puts the short issue number at the beginning of the commit message and adds the full issue id (organization/repository#issueId) at the end. 

#!/bin/bash

# This hook works for branches named such as "123-description" and will add "[#123]" to the commit message.

# get current branch
branchName=`git rev-parse --abbrev-ref HEAD`

# search for the issue id in the branch name, such as "123-description" or "XXX-123-description"
issueId=$(echo $branchName | sed -nE 's,([A-Z]?-?[0-9]+)-.+,\1,p')

# only prepare commit message if pattern matched and issue id was found
if [[ ! -z $issueId ]]; then
 # $1 is the name of the file containing the commit message
 # We prepend the issue number at the beginning (so we can easily see it in history)
 # And also we append the full issue id (with the organization/repository# prefix),
 # so this commit hook works for other repositories (frontend) too.
 echo -e "[#$issueId] ""$(cat $1)""\n[organization/repository#$issueId]" > "$1"
 # sed -i.bak -e "1s/^/\n\n[$issueId]\n/" $1
 # echo -e "[$issueId]\n""$(cat $1)" > "$1"
 # sed -i.bak -e "1s/^/$TRIMMED /" $1
fi

Installing the Hook

  • Create the .git/hooks/prepare-commit-msg script
  • Copy the content from the snippet above
  • Make the file executable: chmod +x .git/hooks/prepare-commit-msg
  • Try to commit something and check that the issue number is automatically added

Note: when you do commit --amend, the issue number will be added for the second time - you need to remove it manually.

Tags: git

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