Git pre-commit hook for large files

Git pre-commit hook for large files.md

Git pre-commit hook for large files

This hook warns you before you accidentally commit large files to git. It's very hard to reverse such an accidental commit, so it's better to prevent it in advance.

Since you will likely want this script to run in all your git repos, a script is attached to add this hook to all git repos you create / clone in the future.

Of course, you can just download it directly to the hooks in an existing git repo.

Configuration

The default limit is max 5MB per file. If you feel that your commit is a special case, you can always override the limit with:

GIT_FILE_SIZE_LIMIT=42000000 git commit -m "This commit is allowed file sizes up to 42MB"

Contents

• pre-commit : The hook itself
• install.sh : Installs this hook to your git template directory.

Usage

You can use in two ways.

1. Directly as the pre-commit hook in your .git/hooks folder.
2. With Husky by updating your package.json with:

"husky": {
    "hooks": {
      "pre-commit": "sh ./some-path/pre-commit-prevent-large-files.sh"
    }
}

Installation

To install this for all future repositories

curl -L https://gist.github.com/danmackinlay/6e4a0e5c38a43972a0de2938e6ddadba/raw/install.sh | bash

For just the current one (erasing any existing pre-commit hooks)

curl -L https://gist.github.com/danmackinlay/6e4a0e5c38a43972a0de2938e6ddadba/raw/pre-commit > .git/hooks/pre-commit
chmod a+x .git/hooks/pre-commit

Credits

Based on @kiwidamien's original gist here.

Adapted from: https://gist.github.com/benmccallum/28e4f216d9d72f5965133e6c43aaff6e

Help from this stackoverflow question.

This version is based on @guysmoilov’s fork which adds a neat isntaller script.

Alternatives

pre-commit is "a framework for managing and maintaining multi-language pre-commit hooks" and has a hook you can plug-in called: check-added-large-files. pre-commit is built with Python though, so you'll need Python installed.

install.sh

#!/bin/sh
set -e
echo "Starting install script..."

SET_GIT_TEMPLATE_DIR=false
EXISTING_TEMPLATE=$(git config --global init.templateDir || echo "")
if [ -z "$EXISTING_TEMPLATE" ]; then
  echo "Creating a new global git template dir at ~/.git_template"
  mkdir ~/.git_template
  EXISTING_TEMPLATE="$(cd ~; pwd -P)/.git_template"
  SET_GIT_TEMPLATE_DIR=true
else
  EXISTING_TEMPLATE="$(eval cd $(dirname "$EXISTING_TEMPLATE"); pwd -P)/$(basename "$EXISTING_TEMPLATE")"
  echo "Using existing git template dir: $EXISTING_TEMPLATE"
fi

HOOKS_DIR="$EXISTING_TEMPLATE/hooks"
PRECOMMIT_HOOK="$HOOKS_DIR/pre-commit"
echo "Creating hooks dir if it doesn't already exist: $HOOKS_DIR"
mkdir -p "$HOOKS_DIR"
if [ -f "$PRECOMMIT_HOOK" ]; then
  echo "Cannot install hook as it's already defined: '$PRECOMMIT_HOOK'" >&2
  exit 1
fi

echo "Downloading the hook to $PRECOMMIT_HOOK"
curl -L https://gist.github.com/guysmoilov/ddb3329e31b001c1e990e08394a08dc4/raw/pre-commit -o "$PRECOMMIT_HOOK" 2> /dev/null

echo "Making it executable"
chmod +x "$PRECOMMIT_HOOK"

if [ "$SET_GIT_TEMPLATE_DIR" = true ]; then
  echo "Defining ~/.git_template as the global git template dir"
  git config --global init.templateDir '~/.git_template'
fi

echo -e "\nDone! Any future git repo created in this user profile will contain the hook\n"

pre-commit

#!/bin/bash

# This is a pre-commit hook that ensures attempts to commit files that are
# larger than $limit to your _local_ repo fail, with a helpful error message.

# Maximum file size limit in bytes
limit=$(( 5 * 2**20 )) # 5MB
limitInMB=$(( $limit / 2**20 ))

# Move to the repo root so git files paths make sense
repo_root=$( git rev-parse --show-toplevel )
cd $repo_root

empty_tree=$( git hash-object -t tree /dev/null )

if git rev-parse --verify HEAD > /dev/null 2>&1
then
	against=HEAD
else
	against="$empty_tree"
fi

# Set split so that for loop below can handle spaces in file names by splitting on line breaks
IFS='
'

echo "Checking staged file sizes"
shouldFail=false
# `--diff-filter=d` -> skip deletions
for file in $( git diff-index --cached --diff-filter=d --name-only "$against" ); do
	# Skip for directories (git submodules)
	if [[ -f "$file" ]]; then
		file_size=$( ls -lan $file | awk '{ print $5 }' )
		if [ "$file_size" -gt  "$limit" ]; then
	    	echo File $file is $(( $file_size / 2**20 )) MB, which is larger than our configured limit of $limitInMB MB
        	shouldFail=true
		fi
	fi
done

if $shouldFail
then
    echo If you really need to commit this file, you can push with the --no-verify switch, but the file should definitely, definitely be under $limitInMB MB!!!
	  echo Commit aborted
    exit 1;
fi