prepare-commit-msg git hook to add jira ticket number to beginning of the commit msg

prepare-commit-msg

#!/bin/bash

# Hook based on this article: https://andy-carter.com/blog/automating-git-commit-messages-with-git-hooks

COMMIT_MSG_FILE=$1
COMMIT_SOURCE=$2
SHA1=$3

branch=$(git branch --show-current)

# Link to regex matches: https://regex101.com/r/6X9gfO/1
regex="[A-Z]{3,10}-[0-9]{1,5}"

# checking for message as source to skip changing the commit message
# when it's a --amend
if [[ $COMMIT_SOURCE == "message" ]] &&
    [[ $branch =~ $regex ]]; then
    echo "Adding ticket number to commit"
    ticket_number=$BASH_REMATCH      
    commit_message=$( < $COMMIT_MSG_FILE)
    # Use printf to preserve the formatting of the commit message
    printf "%s %s" "$ticket_number" "$commit_message" > "$COMMIT_MSG_FILE"
fi

When using the script, make sure your file is executable. For example, my file was under ~/.config/global-git-hooks, so the command will be:

chmod +x ~/.config/global-git-hooks/prepare-commit-msg

If you would like to, you can add it to global hooks, to be applied to every commit, instead of locally on the project (which would require to be done in every project .git folder). For using it globally, add the path of the folder containing your hook to the git core.hooksPath configuration. Still on the folder from before, the command will be:

git config --global core.hooksPath ~/.config/global-git-hooks