sbt-header

sbt-header is an sbt plugin for creating or updating file headers, e.g. copyright headers.

Getting started

In order to add the sbt-header plugin to your build, add the following line to project/plugins.sbt:

addSbtPlugin("de.heikoseeberger" % "sbt-header" % "5.6.0") // Check the latest version above or look at the release tags

Then in your build.sbt configure the following settings:

organizationName := "Heiko Seeberger"
startYear := Some(2015)
licenses += ("Apache-2.0", new URL("https://www.apache.org/licenses/LICENSE-2.0.txt"))

This configuration will apply Apache License 2.0 headers to Scala and Java files. sbt-header provides two tasks: headerCreate and headerCheck, which are described in the following sub sections. For more information on how to customize sbt-header, please refer to the Configuration section.

Creating headers

In order to create or update file headers, execute the headerCreate task:

> headerCreate
[info] Headers created for 2 files:
[info]   /Users/heiko/projects/sbt-header/sbt-header-test/test.scala
[info]   /Users/heiko/projects/sbt-header/sbt-header-test/test2.scala

The task is incremental, meaning that it will not look at files that have not seen changes since the last time the task was run.

Checking headers

In order to check whether all files have headers (for example for CI), execute the headerCheck task:

> headerCheck
[error] (compile:checkHeaders) There are files without headers!
[error]   /Users/heiko/projects/sbt-header/sbt-header-test/test.scala
[error]   /Users/heiko/projects/sbt-header/sbt-header-test/test2.scala

headerCheck will not modify any files but will cause the build to fail if there are files without a license header.

Requirements

• Java 8 or higher
• sbt 1.0.0 or higher

Configuration

By default sbt-header tries to infer the license header you want to use from the organizationName, startYear and licenses settings. For this to work, sbt-header requires the licenses setting to contain exactly one entry. The first component of that entry has to be the SPDX license identifier of one of the supported licenses.

Setting the license to use explicitly

If you can not setup your build in a way that sbt-header can detect the license you want to use (see above), you can set the license to use explicitly:

headerLicense := Some(HeaderLicense.MIT("2015", "Heiko Seeberger"))

This will also be given precedence if a license has been auto detected from project settings.

Build in licenses

The most common licenses have been pre-canned in License. They can either be detected using their SPDX identifier or by setting them explicitly.

Using the short SPDX license identifier syntax

If you want to use the following syntax:

  /*
   * Copyright 2015 Heiko Seeberger
   *
   * SPDX-License-Identifier: BSD-3-Clause
   */

You have two possibilites:

• If you are using auto-detection, you just need to add the following to your build.sbt

headerLicenseStyle := HeaderLicenseStyle.SpdxSyntax

• On the other hand, if you are defining your license explicitly, you'll have to pass the style when defining the headerLicense attribute:

headerLicense := Some(HeaderLicense.MIT("2015", "Heiko Seeberger", HeaderLicenseStyle.SpdxSyntax))

Using a custom license text

If you don't want to use one of the built-in licenses, you can define a custom license text using the Custom case class:

headerLicense := Some(HeaderLicense.Custom(
  """|Copyright (c) Awesome Company 2015
     |
     |This is the custom License of Awesome Company
     |""".stripMargin
))

Note that you don't need to add comment markers like // or /*. The comment style is configured on a per file type basis (see next section).

Configuring comment styles

Comment styles are configured on a per file type basis. The default is to apply C Style block comments to Scala and Java files. No other comment styles are predefined. If you want to create comments for example for your XML files, you have to add the corresponding mapping manually (see below). The build-in comment styles are defined in CommentStyle:

To override the configuration for Scala/Java files or add a configuration for some other file type, use the headerMapping setting:

headerMappings := headerMappings.value + (HeaderFileType.scala -> HeaderCommentStyle.cppStyleLineComment)

Custom comment creators

You can customize how content gets created by providing your own CommentCreator. For example, this would be a (crude) way to preserve the copyright year in existing headers but still update the rest:

CommentStyle.cStyleBlockComment.copy(commentCreator = new CommentCreator() {
  val Pattern = "(?s).*?(\\d{4}(-\\d{4})?).*".r
  def findYear(header: String): Option[String] = header match {
   case Pattern(years, _) => Some(years)
    case _                 => None
  }
  override def apply(text: String, existingText: Option[String]): String = {
    val newText = CommentStyle.cStyleBlockComment.commentCreator.apply(text, existingText)
    existingText
      .flatMap(findYear)
      .map(year => newText.replace("2017", year))
      .getOrElse(newText)
  }
})

Excluding files

To exclude some files, use the sbt's file filters:

excludeFilter.in(headerSources) := HiddenFileFilter || "*Excluded.scala"
excludeFilter.in(headerResources) := HiddenFileFilter || "*.xml"

Empty line between header and body

If an empty line header should be added between the header and the body of a file (defaults to true):

headerEmptyLine := false

Using an auto plugin

If your build uses an auto plugin for common settings, make sure to add HeaderPlugin to requires:

import de.heikoseeberger.sbtheader.HeaderPlugin

object Build extends AutoPlugin {
  override def requires = ... && HeaderPlugin
  ...
}

Adding headers to files in other configurations

By default sbt-header takes Compile and Test configurations into account. If you need more, just add them:

headerSettings(It, MultiJvm)

Automation

If you want to automate header creation/update on compile, enable the AutomateHeaderPlugin:

lazy val myProject = project
  .in(file("."))
  .enablePlugins(AutomateHeaderPlugin)

By default automation takes Compile and Test configurations into account. If you need more, just add them:

automateHeaderSettings(It, MultiJvm)

Integration with other plugins

This plugin by default only handles managedSources and managedResources in Compile and Test. For this reason you need to tell sbt-header if it should also add headers to additional files managed by other plugins.

sbt-twirl / play projects

To use sbt-header in a project using sbt-twirl (for example a Play web project), the Twirl templates have to be added to the sources handled by sbt-header. Add the following to your build definition:

import de.heikoseeberger.sbtheader.FileType
import play.twirl.sbt.Import.TwirlKeys

headerMappings := headerMappings.value + (FileType("html") -> HeaderCommentStyle.twirlStyleBlockComment)

headerSources.in(Compile) ++= sources.in(Compile, TwirlKeys.compileTemplates).value

sbt-header supports two comment styles for Twirl templates. twirlStyleBlockComment will produce simple twirl block comments, while twirlStyleFramedBlockComment will produce framed twirl comments.

twirlStyleBlockComment comment style:

@*
 * This is a simple twirl block comment
 *@

twirlStyleFramedBlockComment comment style:

@**********************************
 * This is a framed twirl comment *
 **********************************@

sbt-boilerplate

In order to use sbt-header with sbt-boilerplate plugin add the following to your build definition:

def addBoilerplate(confs: Configuration*) = confs.foldLeft(List.empty[Setting[_]]) { (acc, conf) =>
  acc ++ Seq(
    headerSources in conf ++= (((sourceDirectory in conf).value / "boilerplate") ** "*.template").get),
    headerMappings        += (FileType("template") -> HeaderCommentStyle.cStyleBlockComment)
  )
}

addBoilerplate(Compile, Test)

This adds src/{conf}/boilerplate/**.scala in the list of files handled by sbt-headers for conf, where conf is either Compile or Test.

Migrating from 1.x

This section contains migration notes from version 1.x of sbt-header to version 2.x. The latest release of the 1.x line is 1.8.0. You can find the documentation of that release in the corresponding git tag.

Changed task names and settings keys

The names of all tasks and settings have been changed from 1.x to 2.x. Furthermore types of settings have changed. The following tables give an overview of the changes:

Changed task names:

Changed settings:

createFrom method

sbt-header 1.x featured some default header mappings as well as the createFrom method, which could be used to easily define header mappings:

headers := createFrom(Apache2_0, "2015", "Heiko Seeberger")

This method has been removed and the default mappings for Scala and Java files has been added as default mapping to the headerMappings setting.

Custom licenses

In sbt-header 1.x when you needed to use a custom license this would typically look like this:

headers := Map(
  "scala" -> (
    HeaderPattern.cStyleBlockComment,
    """|/*
       | * Copyright 2015 Awesome Company
       | */
       |""".stripMargin
  )
)

In sbt-header 2.x, licenses are defined as instances of de.hseeberger.sbtheader.License. Further more, the license is only defined once and not per file type. So the above in 2.x is equivalent to:

headerLicense := Some(HeaderLicense.Custom(
    """|Copyright 2015 Awesome Company
       |""".stripMargin
))

Note that you only need to define the license text, but not the comment markers. The latter are configured via the headerMappings setting. The configuration above will use the default mappings which apply C style block comments to Java and Scala files. If you have mappings for additional file types, please add these to the headerMappings setting.

Dropped features

In sbt-header 1.x it was possible to define different licenses for different files types, e.g.:

headers := Map(
  "scala" -> Apache2_0("2015", "Heiko Seeberger"),
  "java" -> MIT("2015", "Heiko Seeberger")
)

Since we believe most of the projects out there will only ever have one license, we dropped this feature without replacement. In sbt-header 2.x users have to define a single license for the whole project using the headerLicense setting (or let sbt-header infer it from the licenses project setting, see above) and a mapping from file type to comment style using the headerMappings setting.

Contribution policy

Contributions via GitHub pull requests are gladly accepted from their original author. Along with any pull requests, please state that the contribution is your original work and that you license the work to the project under the project's open source license. Whether or not you state this explicitly, by submitting any copyrighted material via pull request, email, or other means you agree to license the material under the project's open source license and warrant that you have the legal authority to do so.

License

This code is open source software licensed under the Apache 2.0 License.