cb109 · August 16, 2024 08:26
diff --git a/check_for_git_merge_conflicts_on_master.sh b/check_for_git_merge_conflicts_on_master.sh
 #!/bin/bash

 # In this example we want to execute 'git pull' on the local 'master' branch, but we
 # want to make sure that pull won't introduce conflicts and by that a broken checkout.
 # The script below will do an in-memory merge of the upstream master and local master
 # and exit with a non-zero code if that merge produced any conflicts.
 #
 # A snippet like this is useful for deployment scripts that involve 'git pull' to 
 # prevent breaking production if for some reason a conflict has bypassed CI.
 #
 # Tools like the GitHub Pull Request interface does this under the hood already and 
 # warns you about potential conflicts, while preventing a merge. For custom tooling,
 # this script serves as an equivalent for that.

 set -e

 # Get tracked upstream for local branch: https://stackoverflow.com/a/16879922
 upstream_master="$(git rev-parse --abbrev-ref master@{upstream})"

 merge_this=$upstream_master
 into_that=master

 # Merge in-memory, extract conflict from diff: https://stackoverflow.com/a/63777004
 git fetch --all
 conflict="$(git merge-tree $(git merge-base $merge_this $into_that) $into_that $merge_this | sed -ne '/^\+<<</,/^\+>>>/ p')"

 if [ -z "$conflict" ]
 then
  printf "Testing if we can merge $merge_this -> $into_that, no conflicts found, good to go!\n"
 else
  printf "Testing if we can merge $merge_this -> $into_that, but there are conflicts:\n\n"
  # Quote variable on echo to preserve newlines: https://stackoverflow.com/a/22101842
  printf "$conflict"
  printf "\n\nAborting merge, please resolve the conflicts and push the fix before trying again.\n"
  exit 1
 fi
	#!/bin/bash

	# In this example we want to execute 'git pull' on the local 'master' branch, but we
	# want to make sure that pull won't introduce conflicts and by that a broken checkout.
	# The script below will do an in-memory merge of the upstream master and local master
	# and exit with a non-zero code if that merge produced any conflicts.
	#
	# A snippet like this is useful for deployment scripts that involve 'git pull' to
	# prevent breaking production if for some reason a conflict has bypassed CI.
	#
	# Tools like the GitHub Pull Request interface does this under the hood already and
	# warns you about potential conflicts, while preventing a merge. For custom tooling,
	# this script serves as an equivalent for that.

	set -e

	# Get tracked upstream for local branch: https://stackoverflow.com/a/16879922
	upstream_master="$(git rev-parse --abbrev-ref master@{upstream})"

	merge_this=$upstream_master
	into_that=master

	# Merge in-memory, extract conflict from diff: https://stackoverflow.com/a/63777004
	git fetch --all
	conflict="$(git merge-tree $(git merge-base $merge_this $into_that) $into_that $merge_this \| sed -ne '/^\+<<</,/^\+>>>/ p')"

	if [ -z "$conflict" ]
	then
	printf "Testing if we can merge $merge_this -> $into_that, no conflicts found, good to go!\n"
	else
	printf "Testing if we can merge $merge_this -> $into_that, but there are conflicts:\n\n"
	# Quote variable on echo to preserve newlines: https://stackoverflow.com/a/22101842
	printf "$conflict"
	printf "\n\nAborting merge, please resolve the conflicts and push the fix before trying again.\n"
	exit 1
	fi