Git config and hook to add trailer automatically to commit messages

config.ini

# Requires branch named in format `zz/key-1234/some-short-desc
# Results in commit with trailer:
#    TASK: KEY-1234
#
[trailer "task"]                                                                                                                                                                                            
  key = "Task: "                                                                                                                                                                                      
  ifExists = replace                                                                                                                                                                                  
  ifMissing = add
  cmd = git rev-parse --abbrev-ref HEAD | awk -F/ '{ print toupper($2) }'                                                                                                                         
  

prepare-commit-msg.sh

#!/bin/sh

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

git interpret-trailers --in-place "$COMMIT_MSG_FILE"