19 releases (stable)

new 5.7.0 Jul 3, 2024
5.6.0 Jun 19, 2024
5.5.1 Apr 24, 2024
5.4.0 Mar 31, 2024

#229 in Configuration

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Used in hawkeye


1.5K SLoC


Simple license header checker and formatter, in multiple distribution forms.


You can use HawkEye in GitHub Actions or in your local machine. HawkEye provides three basic commands:

# check license headers
hawkeye check

# format license headers (auto-fix all files that failed the check)
hawkeye format

# remove license headers
hawkeye remove

You can use -h or --help to list out all config options.

GitHub Actions

The HawkEye GitHub Action enables users to run license header check by HawkEye with a config file.

First of all, add a licenserc.toml file in the root of your project. The simplest config for projects licensed under Apache License 2.0 is as below:

[!NOTE] The full configurations can be found in the configuration section.

headerPath = "Apache-2.0.txt"

inceptionYear = 2023
copyrightOwner = "tison <wander4096@gmail.com>"

You should change the copyright line according to your information.

To check license headers in GitHub Actions, add a step in your GitHub workflow:

- name: Check License Header
  uses: korandoru/hawkeye@v5


Alpine image (~18MB):

docker run -it --rm -v $(pwd):/github/workspace ghcr.io/korandoru/hawkeye check

Arch Linux

[!NOTE] Reach out to the maintainer (@orhun) of the package or report issues on Arch Linux GitLab in the case of packaging-related problems.

hawkeye can be installed with pacman:

pacman -S hawkeye

Cargo Install

The hawkeye executable can be installed by:

cargo install hawkeye

Prebuilt Binary

Instead of cargo install, you can install hawkeye as a prebuilt binary by:

export VERSION=v5.3.1
curl --proto '=https' --tlsv1.2 -LsSf https://github.com/korandoru/hawkeye/releases/download/$VERSION/hawkeye-installer.sh | sh

It would retain more build info (output by hawkeye -V) than cargo install.


This steps requires Rust toolchain.

cargo build --workspace --all-features --bin --tests --examples --benches

Build Docker image:

docker build . -t hawkeye


Config file

# Base directory for the whole execution.
# All relative paths is based on this path.
# default: current working directory
baseDir = "."

# Inline header template.
# Either inlineHeader or headerPath should be configured, and inlineHeader is prioritized.
inlineHeader = "..."

# Path to the header template file.
# Either inlineHeader or headerPath should be configured, and inlineHeader is prioritized.
# This path is resolved by the ResourceFinder. Check ResourceFinder for the concrete strategy.
# The header template file is skipped on any execution.
headerPath = "path/to/header.txt"

# On enabled, check the license header matches exactly with whitespace.
# Otherwise, strip the header in one line and check.
# default: true
strictCheck = true

# Whether you use the default excludes. Check Default.EXCLUDES for the completed list.
# To suppress part of excludes in the list, declare exact the same pattern in `includes` list.
# default: true
useDefaultExcludes = true

# The supported patterns of includes and excludes follow gitignore pattern format, plus that:
# 1. `includes` does not support `!`
# 2. backslash does not escape letter
# 3. whitespaces and `#` are normal since we configure line by line
# See also https://git-scm.com/docs/gitignore#_pattern_format

# Patterns of path to be included on execution.
# default: all the files under `baseDir`.
includes = ["..."]

# Patterns of path to be excluded on execution. A leading bang (!) indicates an invert exclude rule.
# default: empty; if useDefaultExcludes is true, append default excludes.
excludes = ["..."]

# Keywords that should occur in the header, case-insensitive.
# default: ["copyright"]
keywords = ["copyright", "..."]

# Whether you use the default mapping. Check DocumentType.defaultMapping() for the completed list.
# default: true
useDefaultMapping = true

# Paths to additional header style files. The model of user-defined header style can be found below.
# default: empty
additionalHeaders = ["..."]

# Mapping rules (repeated).
# The key of a mapping rule is a header style type (case-insensitive).
# Available header style types consist of those defined at `HeaderType` and user-defined ones in `additionalHeaders`.
# The name of header style type is case-insensitive.
# If useDefaultMapping is true, the mapping rules defined here can override the default one.
filenames = ["..."]  # e.g. "Dockerfile.native"
extensions = ["..."] # e.g. "cc"

# Properties to fulfill the template.
# For a defined key-value pair, you can use ${key} in the header template, which will be substituted
# with the corresponding value.
# Preset properties:
# * 'hawkeye.core.filename' is the current file name, like: pom.xml.
inceptionYear = 2023

# Options to configure Git features.
# If enabled, do not process files that are ignored by Git; possible value: ['auto', 'enable', 'disable']
# 'auto' means this feature tries to be enabled with:
#   * gix - if `basedir` is in a Git repository.
#   * ignore crate's gitignore rules - if `basedir` is not in a Git repository.
# 'enable' means always enabled with gix; failed if it is impossible.
# default: 'auto'
ignore = 'auto'
# If enabled, populate file attrs determinated by Git; possible value: ['auto', 'enable', 'disable']
# Attributes contains:
#   * 'hawkeye.git.fileCreatedYear'
#   * 'hawkeye.git.fileModifiedYear'
# 'auto' means this feature tries to be enabled with:
#   * gix - if `basedir` is in a Git repository.
# 'enable' means always enabled with gix; failed if it is impossible.
# default: 'disable'
attrs = 'disable'

Header style file

# [REQUIRED] The name of this header.

# The first fixed line of this header. Default to none.
firstLine = "..."

# The last fixed line of this header. Default to none.
endLine = "..."

# The characters to prepend before each license header lines. Default to empty.
beforeEachLine = "..."

# The characters to append after each license header lines. Default to empty.
afterEachLine = "..."

# Only for multi-line comments: specify if blank lines are allowed.
# Default to false because most of the time, a header has some characters on each line.
allowBlankLines = false

# Specify whether this is a multi-line comment style or not.
# A multi-line comment style is equivalent to what we have in Java, where a first line and line will delimit
# a whole multi-line comment section.
# A style that is not multi-line is usually repeating in each line the characters before and after each line
# to delimit a one-line comment.
# Defaulut to true.
multipleLines = true

# Only for non multi-line comments: specify if some spaces should be added after the header line and before
# the `afterEachLine` characters so that all the lines are aligned.
# Default to false.
padLines = false

# A regex to define a first line in a file that should be skipped and kept untouched, like the XML declaration
# at the top of XML documents.
# Default to none.
skipLinePattern = "..."

# [REQUIRED] The regex used to detect the start of a header section or line.
firstLineDetectionPattern = "..."

# [REQUIRED] The regex used to detect the end of a header section or line.
lastLineDetectionPattern = "..."


Apache License 2.0


This software is originally from license-maven-plugin,with an initial motivation to bring it beyond a Maven plugin. The core abstractions like Document, Header, and HeaderParser are originally copied from the license-maven-plugin sources under the terms of Apache License 2.0.

Later, when I started focusing on the Docker image's size and integrate with Git, I found that Rust is better than Java (GraalVM Native Image) for this purpose. So I rewrote the core logic in Rust and keep ship a slim image.


~567K SLoC