full_guide.md

Installation

Add Lefthook to your system or build it from sources.

go

go get github.com/evilmartians/lefthook

npm or yarn

npm i @arkweid/lefthook --save-dev
# or yarn:
yarn add -D @arkweid/lefthook

NOTE: if you install it this way you should call it with npx or yarn for all listed examples below. (for example: lefthook install -> npx lefthook install)

You can also install lefthook as a global dependency

npm install -g @arkweid/lefthook

Rubygems

gem install lefthook

Homebrew for MacOS and Linux

brew install lefthook

AUR for Arch

You can install lefthook package from AUR

Snap for Linux

snap install --classic lefthook

APT packages for Debian/Ubuntu Linux

curl -1sLf 'https://dl.cloudsmith.io/public/evilmartians/lefthook/setup.deb.sh' | sudo -E bash
sudo apt install lefthook

See all instructions: https://cloudsmith.io/~evilmartians/repos/lefthook/setup/#formats-deb

RPM packages for CentOS/Fedora Linux

curl -1sLf 'https://dl.cloudsmith.io/public/evilmartians/lefthook/setup.rpm.sh' | sudo -E bash
sudo yum install lefthook

See all instructions: https://cloudsmith.io/~evilmartians/repos/lefthook/setup/#repository-setup-yum

Anything else

Or take it from binaries and install manually

Scenarios

Examples

We have a directory with few examples. You can check it here.

First time user

Initialize lefthook with the following command

lefthook install

It creates lefthook.yml in the project root directory

Register your hook (You can choose any hook from this list) In our example it pre-push githook:

lefthook add pre-push

Describe pre-push commands in lefthook.yml:

pre-push: # githook name
  commands: # list of commands
    packages-audit: # command name
      run: yarn audit # command for execution

That's all! Now on git push the yarn audit command will be run. If it fails the git push will be interrupted.

If you already have a lefthook config file

Just initialize lefthook to make it work :)

lefthook install

More options

Use glob patterns to choose what files you want to check

# lefthook.yml

pre-commit:
  commands:
    lint:
      glob: "*.{js,ts,jsx,tsx}"
      run: yarn eslint

Select specific file groups

In some cases you want to run checks only against some specific file group. For example: you may want to run eslint for staged files only.

There are two shorthands for such situations: {staged_files} - staged git files which you try to commit

{all_files} - all tracked files by git

# lefthook.yml

pre-commit:
  commands:
    frontend-linter:
      glob: "*.{js,ts,jsx,tsx}" # glob filter for list of files
      run: yarn eslint {staged_files} # {staged_files} - list of files
    backend-linter:
      glob: "*.rb" # glob filter for list of files
      exclude: "application.rb|routes.rb" # regexp filter for list of files
      run: bundle exec rubocop --force-exclusion {all_files} # {all_files} - list of files

Note: If using all_files with RuboCop, it will ignore RuboCop's Exclude configuration setting. To avoid this, pass --force-exclusion.

Custom file list

Lefthook can be even more specific in selecting files. If you want to choose diff of all changed files between the current branch and master branch you can do it this way:

# lefthook.yml

pre-push:
  commands:
    frontend-style:
      files: git diff --name-only master # custom list of files
      glob: "*.js"
      run: yarn stylelint {files}

{files} - shorthand for a custom list of files

Git hook argument shorthands in commands

If you want to use the original Git hook arguments in a command you can do it using the indexed shorthands:

# lefthook.yml

# Note: commit-msg hook takes a single parameter,
# the name of the file that holds the proposed commit log message.
# Source: https://git-scm.com/docs/githooks#_commit_msg
commit-msg:
  commands:
    multiple-sign-off:
      run: 'test $(grep -c "^Signed-off-by: " {1}) -lt 2'

{0} - shorthand for the single space-joint string of Git hook arguments

{i} - shorthand for the i-th Git hook argument

Managing scripts

If you run lefthook add command with -d flag, lefthook will create two directories where you can put scripts and reference them from lefthook.yml file.

Example: Let's create commit-msg hook with -d flag

lefthook add -d commit-msg

This command will create .lefthook/commit-msg and .lefthook-local/commit-msg dirs.

The first one is for common project level scripts. The second one is for personal scripts. It would be a good idea to add dir.lefthook-local to .gitignore.

Create scripts .lefthook/commit-msg/hello.js and .lefthook/commit-msg/hi.rb

# lefthook.yml

commit-msg:
  scripts:
    "hello.js":
      runner: node
    "hi.rb":
      runner: ruby

Bash script example

Let's create a bash script to check commit templates .lefthook/commit-msg/template_checker:

INPUT_FILE=$1
START_LINE=`head -n1 $INPUT_FILE`
PATTERN="^(TICKET)-[[:digit:]]+: "
if ! [[ "$START_LINE" =~ $PATTERN ]]; then
  echo "Bad commit message, see example: TICKET-123: some text"
  exit 1
fi

Now we can ask lefthook to run our bash script by adding this code to lefthook.yml file:

# lefthook.yml

commit-msg:
  scripts:
    "template_checker":
      runner: bash

When you try to commit git commit -m "haha bad commit text" script template_checker will be executed. Since commit text doesn't match the described pattern the commit process will be interrupted.

Local config

We can use lefthook-local.yml as local config. Options in this file will overwrite options in lefthook.yml. (Don't forget to add this file to .gitignore)

Skipping commands

You can skip commands by skip option:

# lefthook-local.yml

pre-push:
  commands:
    packages-audit:
      skip: true

Skipping commands during rebase or merge

You can skip commands during rebase and/or merge by the same skip option:

pre-push:
  commands:
    packages-audit:
      skip: merge

# or

pre-push:
  commands:
    packages-audit:
      skip:
        - merge
        - rebase

Skipping commands by tags

If we have a lot of commands and scripts we can tag them and run skip commands with a specific tag.

For example, if we have lefthook.yml like this:

# lefthook.yml

pre-push:
  commands:
    packages-audit:
      tags: frontend security
      run: yarn audit
    gems-audit:
      tags: backend security
      run: bundle audit

You can skip commands by tags:

# lefthook-local.yml

pre-push:
  exclude_tags:
    - frontend

Piped option

If any command in the sequence fails, the other will not be executed.

# lefthook.yml

database:
  piped: true
  commands:
    1_create:
      run: rake db:create
    2_migrate:
      run: rake db:migrate
    3_seed:
      run: rake db:seed

Extends option

If you need to extend config from some another place, just add top level:

# lefthook.yml

extends:
  - $HOME/work/lefthook-extend.yml
  - $HOME/work/lefthook-extend-2.yml

NOTE: Files for extend should have name NOT a "lefthook.yml" and should be unique.

Referencing commands from lefthook.yml

If you have the following config

# lefthook.yml

pre-commit:
  scripts:
    "good_job.js":
      runner: node

You can wrap it in docker runner locally:

# lefthook-local.yml

pre-commit:
  scripts:
    "good_job.js":
      runner: docker run -it --rm <container_id_or_name> {cmd}

{cmd} - shorthand for the command from lefthook.yml

Run githook group directly

lefthook run pre-commit

Parallel execution

You can enable parallel execution if you want to speed up your checks. Lets get example from discourse project.

bundle exec rubocop --parallel && \
bundle exec danger && \
yarn eslint --ext .es6 app/assets/javascripts && \
yarn eslint --ext .es6 test/javascripts && \
yarn eslint --ext .es6 plugins/**/assets/javascripts && \
yarn eslint --ext .es6 plugins/**/test/javascripts && \
yarn eslint app/assets/javascripts test/javascripts

Rewrite it in lefthook custom group. We call it lint:

# lefthook.yml

lint:
  parallel: true
  commands:
    rubocop:
      run: bundle exec rubocop --parallel
    danger:
      run: bundle exec danger
    eslint-assets:
      run: yarn eslint --ext .es6 app/assets/javascripts
    eslint-test:
      run: yarn eslint --ext .es6 test/javascripts
    eslint-plugins-assets:
      run: yarn eslint --ext .es6 plugins/**/assets/javascripts
    eslint-plugins-test:
      run: yarn eslint --ext .es6 plugins/**/test/javascripts
    eslint-assets-tests:
      run: yarn eslint app/assets/javascripts test/javascripts

Then call this group directly:

lefthook run lint

Complete example

# lefthook.yml
color: false
extends: $HOME/work/lefthook-extend.yml

pre-commit:
  commands:
    eslint:
      glob: "*.{js,ts,jsx,tsx}"
      run: yarn eslint {staged_files}
    rubocop:
      tags: backend style
      glob: "*.rb"
      exclude: "application.rb|routes.rb"
      run: bundle exec rubocop --force-exclusion {all_files}
    govet:
      tags: backend style
      files: git ls-files -m
      glob: "*.go"
      run: go vet {files}

  scripts:
    "hello.js":
      runner: node
    "any.go":
      runner: go run

  parallel: true

# lefthook-local.yml

pre-commit:
  exclude_tags:
    - backend

  scripts:
    "hello.js":
      runner: docker run -it --rm <container_id_or_name> {cmd}
  commands:
    govet:
      skip: true

Skip lefthook execution

We can set env variable LEFTHOOK to zero for that

LEFTHOOK=0 git commit -am "Lefthook skipped"

Skip some tags on the fly

Use LEFTHOOK_EXCLUDE={list of tags to be excluded} for that

LEFTHOOK_EXCLUDE=ruby,security git commit -am "Skip some tag checks"

Concurrent files overrides

To prevent concurrent problems with read/write files try flock utility.

# lefthook.yml

graphql-schema:
  glob: "{Gemfile.lock,app/graphql/**/*}"
  run: flock webpack/application/typings/graphql-schema.json yarn typings:update && git diff --exit-code --stat HEAD webpack/application/typings
frontend-tests:
  glob: "**/*.js"
  run: flock -s webpack/application/typings/graphql-schema.json yarn test --findRelatedTests {files}
frontend-typings:
  glob: "**/*.js"
  run: flock -s webpack/application/typings/graphql-schema.json yarn run flow focus-check {files}

Capture ARGS from git in the script

Example script for prepare-commit-msg hook:

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

# ...

Change directory for script files

You can do this through this config keys:

# lefthook.yml

source_dir: ".lefthook"
source_dir_local: ".lefthook-local"

Manage verbosity

You can manage the verbosity using the skip_output config.

Possible values are meta,success,failure,summary.

This config quiets all outputs except failures:

# lefthook.yml

skip_output:
  - meta
  - success
  - summary

You can also do this with an environment variable:

export LEFTHOOK_QUIET="meta,success,summary"

CI integration

Enable CI env variable if it doens't exists on your service by default.

Disable colors

By agrs:

lefthook --no-colors run pre-commit

By config lefthook.yml, just add the option:

colors: false

Version

lefthook version

Uninstall

lefthook uninstall

More info

Have a question? Check the wiki.