A fast, easy-to-use, license header linter for Go.
- Fast. Processes Go files in parallel to quickly lint massive codebases.
- Easy-to-use. Provide a license header template and copyright author, and run.
- Customisable. Configure year formats (Git supported), license header templates, matchers and comment styles.
- Standard. Written as a
go/analysisAnalyzer, making it possible to use with tools like golangci-lint.
| golicenser | go-header | google/addlicense | plantir/go-license | |
|---|---|---|---|---|
| Actively maintained | ✅ | ❌ | ❌ | ❓ |
| Processes files in parallel | ✅ | ❌ | ✅ | ❌ |
| Update existing headers | ✅ | ✅ | ✅ | ❓ |
Uses go/analysis |
✅ | ❌ | ❌ | ❌ |
| Year formats | Multiple options | Limited¹ | Current | Current |
| Git support | ✅ | Limited¹ | ❌ | ❌ |
| Exclude patterns | ✅ (regexp & doublestar) | ❌ | ✅ | ❓ |
Uses Go text/template |
✅ | ❌ | ✅ | ❌ |
| Customise header matcher | ✅ | ❌ | ❌ | ❌ |
| Supports non-Go files | Planned | ❌ | ✅ | ❌ |
| Supported by golangci-lint | Planned | ✅ | ❌ | ❌ |
¹ Supports modified year, Git range, range, and current year
Coming soon.
Pre-built binaries are available from GitHub Releases.
You can also use go install to build and install a binary from source:
go install github.com/joshuasing/golicenser/cmd/golicenser@latestgolicenser -tmpl=MIT -author="Joshua Sing <[email protected]>" ./...
# /golicenser/templates.go:1:1: missing license header
# /golicenser/header.go:1:1: missing license header
# /golicenser/git.go:1:1: invalid license header
# /golicenser/analysis.go:1:1: missing license header
# /golicenser/cmd/golicenser/golicenser.go:1:1: invalid license header
# /golicenser/analysis_test.go:1:1: invalid license header
# /golicenser/header_test.go:1:1: invalid license headerCommand help
golicenser: manages license headers
Usage: golicenser [-flag] [package]
Flags:
-V print version and exit
-all
no effect (deprecated)
-author string
Copyright author
-author-regexp string
Regexp to match copyright author (default: match author)
-c int
display offending line with this many lines of context (default -1)
-comment-style string
Comment style (line, block) (default "line")
-copyright-header-matcher string
Copyright header matcher regexp (used to detect existence of any copyright header) (default "(?i)copyright")
-cpuprofile string
write CPU profile to this file
-debug string
debug flags, any subset of "fpstv"
-diff
with -fix, don't update the files, but print a unified diff
-exclude string
Paths to exclude (doublestar or r!-prefixed regexp, comma-separated) (default "**/testdata/**")
-fix
apply all suggested fixes
-flags
print analyzer flags in JSON
-json
emit JSON output
-matcher string
License header matcher (This is template, when executed it must become valid regexp)
-matcher-escape
Whether to regexp-escape the matcher
-matcher-file string
License header matcher file)
-max-concurrent int
Maximum concurrent processes to use when processing files (default 32)
-memprofile string
write memory profile to this file
-source
no effect (deprecated)
-tags string
no effect (deprecated)
-test
indicates whether test files should be analyzed, too (default true)
-tmpl string
License header template
-tmpl-file string
License header template file (default "license_header.txt")
-trace string
write trace log to this file
-v no effect (deprecated)
-var string
Template variables (e.g. a=Hello,b=Test)
-var-regexp string
Template variable regexps (e.g. 'a=(Hello|World),b=(?i)test'
-year-mode string
Year formatting mode (preserve, preserve-this-year-range, preserve-modified-range, this-year, last-modified, git-range, git-modified-years) (default "preserve")
golicenser uses the Go text/template package to render license templates.
It is recommended to be familiar with the text/template syntax, however only the basics are needed. To use a variable,
the format is {{.variableName}}. For example, a basic template might look like this:
Copyright (c) {{.year}} {{.author}}
Use of this source code is governed by a BSD-style
license that can be found in the LICENSE file.
Custom variables can be configured in order to deduplicate repeated strings.
These variables are provided by golicenser.
year- Copyright year(s) for file. The format is dependent on the configured year mode.author- The copyright author.filename- The current filename. The root for the file is the directory wheregolicenseris run. You can use thebasenamefunction (e.g.{{basename .filename}}) to render only the file name if wanted.
A few basic functions are provided by the text/template package. In addition to these, golicenser adds:
basename(filepath.Base) - Returns the last element of a path.
There may be some cases where you want to exclude certain paths from being linted. You can provide a list of regexp and/or doublestar patterns to be excluded.
Regexp patterns must be prefixed with r!, otherwise the pattern will be parsed
using doublestar.
golicenser provides several "year modes", which are different ways of detecting and displaying the copyright year(s) for a file. The current supported options are:
| Mode | New header | Updated header |
|---|---|---|
preserve |
Current year | Existing year |
preserve-this-year-range |
Current year | Existing year to current year (if different, e.g. 2024-2025) |
preserve-modified-range |
Last modified year | Existing year to last modified year (if different, e.g. 2022-2025) |
this-year |
Current year | Current year |
last-modified |
Last modified year | Last modified year |
git-range |
Git history creation year to last modified year (e.g. 2022-2025) |
Git history creation year to last modified year (e.g. 2022-2025) |
git-modified-list |
List of all modified years from Git history (e.g. 2022, 2024, 2025) |
List of all modified years from Git history (e.g. 2022, 2024, 2025) |
Last modified year is detected using either Git or the local filesystem.
golicenser supports configuring the comment type used for the license headers. The options are:
line- C-style line comments (// test).block- C++-style block comments (/* test */)
golicenser allows changing the regexp matchers used to detect existing license headers, and to tell when they should be replaced.
The matcher is a regexp expression used to match the license headers generated by golicenser (or otherwise used by the project). Matched headers are updated or replaced by golicenser.
By default, the regexp-escaped value of license header template will be used.
In some cases it may be easier to provide the plain license header here, as such it is possible to set MatcherEscape (
or -matcher-escape) to always regexp-escape the matcher value.
Variables are replaced with regexp expressions, in order to match outdated headers (e.g. when modified and the copyright year changes).
author- Provided author regexp (default: author value)filename-.+year-(\d{4})|(\d{4})-(\d{4])|(\d{4})(?:, (\d{4}))+- Matches a single year, year range or listed years.
The copyright header matcher is used to detect any copyright header. By default, (?i)copyright is used, however
this can be customised in order to prevent false-positives.
If a copyright header exists and does not match the header matcher, then a license header will not be created. If a file starts with a comment that does not match the copyright header matcher, then a new license header will be generated.
All contributions are welcome! If you have found something you think could be improved, please feel free to participate by creating an issue or pull request!
Steps to build a golicenser binary from source.
- Make:
make(make deps lint-depsif missing dependencies) - Standalone:
go build -o ./bin/golicenser ./cmd/golicenser/
This project is maintained by Joshua Sing. You can see a list of ways to contact me here: https://joshuasing.dev/#contact
I take the security of my projects very seriously. As such, I strongly encourage responsible disclosure of security vulnerabilities.
If you have discovered a security vulnerability in golicenser, please report it in accordance with the project Security Policy. Never use GitHub issues to report a security vulnerability.
golicenser is distributed under the terms of the MIT License.
For more information, please refer to the LICENSE file.