SBT plugin to help creating resource-generating plugins
Add the following line to your plugins.sbt file:
addSbtPlugin("com.alejandrohdezma" % "sbt-propagate" % "0.2.1")To use this plugin in your repo, you just need some files to propagate and a couple minutes of your time. Here is a step-by-step tutorial on how to do it:
1 - Enable the ResourceGeneratorPlugin in the project from where you want to generate the files later.
lazy val `my-generator` = project
.enablePlugins(ResourceGeneratorPlugin)2 - Add some files that you want to propagate to other projects using resourcesToPropagate.
This setting receives a pair with the original file on the left, and the destination where it
will be copied on other places on the right.
lazy val `my-generator` = project
.enablePlugins(ResourceGeneratorPlugin)
.settings(resourcesToPropagate += "docs/CODE_OF_CONDUCT.md" -> "docs/CODE_OF_CONDUCT.md")
.settings(resourcesToPropagate += "docs/CONTRIBUTING.md" -> "docs/CONTRIBUTING.md")
.settings(resourcesToPropagate += "docs/LICENSE.md" -> "docs/LICENSE.md")
.settings(resourcesToPropagate += ".github/workflows/ci.yml" -> ".github/workflows/ci.yml")
.settings(resourcesToPropagate += ".gitignore" -> ".gitignore")3 - Create an SBT plugin that will generate your files. For that you need to do two things:
3.1 - Enable SbtPlugin in your project:
lazy val `my-generator` = project
.enablePlugins(SbtPlugin, ResourceGeneratorPlugin)3.2 - Create a new object extending AutoPlugin in your src folder.
import sbt._
object MyGeneratorPlugin extends AutoPlugin {
override def trigger = allRequirements
}4 - Extend ResourceGenerator from your AutoPlugin. This class should be already in scope since dependency is automatically added by ResourceGeneratorPlugin.
import sbt._
import com.alejandrohdezma.resource.generator.ResourceGenerator
object MyGeneratorPlugin extends AutoPlugin with ResourceGenerator[Unit] {
override def trigger = allRequirements
}If you want to know what the type-param
Unitmeans here, have a look at Using extra information
5 - Add a task to our newly created plugin to generate the previously stored files. You can call this task whatever you like.
import sbt._
import com.alejandrohdezma.resource.generator.ResourceGenerator
object MyGeneratorPlugin extends AutoPlugin with ResourceGenerator[Unit] {
val generateMyFiles = taskKey[Unit] {
s"Generates the following files: ${resources.mkString(", ")}"
}
override def trigger = allRequirements
}6 - Implement the task under buildSettings:
import sbt._
import sbt.Keys.streams
import com.alejandrohdezma.resource.generator.ResourceGenerator
object MyGeneratorPlugin extends AutoPlugin with ResourceGenerator[Unit] {
val generateMyFiles = taskKey[Unit] {
s"Generates the following files: ${resources.mkString(", ")}"
}
override def trigger = allRequirements
override def buildSettings = Seq(
generateMyFiles := generate((), logger = streams.value.log.info(_))
)
}And that's it! You can now publish this project and start adding it as a plugin in repositories where you want these files propagated.
You will need to ensure your generateMyFiles task is called when this plugin
is updated as well as ensuring that changes are commited to the repository.
You can ensure this manually, but if you use
Scala Steward
to keep your repositories up-to-date it is super easy. Just add the following
lines to the .scala-steward.conf in the root of your repositories:
postUpdateHooks = [
{
command = ["sbt", "generateMyFiles"],
commitMessage = "Run `sbt generateMyFiles`",
groupId = "my.org",
artifactId = "my-generator"
}
]
Once this is in place, whenever the my-generator artifact is updated, Scala
Steward will run sbt generateMyFiles and commit the changes in the same PR
with the update.
This project provides some extras that you can use to improve your generator plugin.
By default, the plugin adds a header similar to this to every file:
# Don't edit this file! It is automatically updated.
# If you want to suggest a change, please open a PR or issue in the original repositoryThis header can be enriched with a link to the original repository just by overriding
repository with the repository name:
import sbt._
import sbt.Keys.streams
import com.alejandrohdezma.resource.generator.ResourceGenerator
object MyGeneratorPlugin extends AutoPlugin with ResourceGenerator[Unit] {
val generateMyFiles = taskKey[Unit] {
s"Generates the following files: ${resources.mkString(", ")}"
}
override def trigger = allRequirements
override def buildSettings = Seq(
generateMyFiles := generate((), logger = streams.value.log.info(_))
)
override def repository: Option[String] = Some("my-org/my-repo")
}
By default it will add headers for MarkDown files (using [comment]: <> ("my comment"))
and for any other file (using #). This functionality can be extended by overriding
resourceTransformers method in your plugin.
import sbt._
import sbt.Keys.streams
import com.alejandrohdezma.resource.generator.ResourceGenerator
object MyGeneratorPlugin extends AutoPlugin with ResourceGenerator[Unit] {
val generateMyFiles = taskKey[Unit] {
s"Generates the following files: ${resources.mkString(", ")}"
}
override def trigger = allRequirements
override def buildSettings = Seq(
generateMyFiles := generate((), logger = streams.value.log.info(_))
)
override def resourceTransformers = super.resourceTransformers.or {
case ((path, extras), content) if path.extension == "xml" =>
val lines = content.split("\n").toList
path -> extras -> s"""${lines.head}
|<!-- Don't edit this file! It is automatically updated -->
|<!-- If you want to suggest a change, please open a PR or issue in the original repository -->
|${lines.tail.mkString("\n")}""".stripMargin
}
}Or if you want to override any existant transformer:
import sbt._
import sbt.Keys.streams
import com.alejandrohdezma.resource.generator.ResourceGenerator
object MyGeneratorPlugin extends AutoPlugin with ResourceGenerator[Unit] {
val generateMyFiles = taskKey[Unit] {
s"Generates the following files: ${resources.mkString(", ")}"
}
override def trigger = allRequirements
override def buildSettings = Seq(
generateMyFiles := generate((), logger = streams.value.log.info(_))
)
override def resourceTransformers = ResourceTransformers {
case ((path, extras), content) if path.extension == "xml" =>
val lines = content.split("\n").toList
path -> extras -> s"""${lines.head}
|<!-- Don't edit this file! It is automatically updated -->
|<!-- If you want to suggest a change, please open a PR or issue in the original repository -->
|${lines.tail.mkString("\n")}""".stripMargin
}.or(super.resourceTransformers)
}Lastly, for the default transfomers if you don't want them to add headers to
specific files, you can override the noHeaderFiles list. By default this list
just contains LICENSE.md:
import sbt._
import sbt.Keys.streams
import com.alejandrohdezma.resource.generator.ResourceGenerator
object MyGeneratorPlugin extends AutoPlugin with ResourceGenerator[Unit] {
val generateMyFiles = taskKey[Unit] {
s"Generates the following files: ${resources.mkString(", ")}"
}
override def trigger = allRequirements
override def buildSettings = Seq(
generateMyFiles := generate((), logger = streams.value.log.info(_))
)
override def noHeaderFiles: List[String] = super.noHeaderFiles :+ "some_file.md"
}You can add descriptions to your resources using comments. By default this is done:
- For markdown files, adding lines like
[comment]: <> (a-description-line). - For any other file, adding lines started with
#.
To mark the end of the description just leave an empty line between the description and the actual resource's contents.
You can enhance this functionality by adding new values to the resourcesToPropagateDescriptionScraper setting:
lazy val `my-generator` = project
.enablePlugins(SbtPlugin, ResourceGeneratorPlugin)
.settings(resourcesToPropagateDescriptionScraper += "xml" -> { lines: List[String] =>
lines.takeWhile(_.startsWith("<!--")).map(_.stripPrefix("<!-- ").stripSuffix(" --"))
})You can use the special "*" as a fallback.
By default, the plugin will recover resource descriptions and expose them using the
resourcesToPropagateDocs. You can then use this setting to create a useful documentation
for your plugin like (using mdoc):
lazy val documentation = project
.enablePlugins(MdocPlugin)
.settings(mdocVariables += "PROPAGATED_RESOURCES" -> propagatedResouces.value)
lazy val propagatedResouces = Def.setting {
(`my-generator` / resourcesToPropagateDocs).value.map { case (resource, destination, description) =>
s"### :octocat: [$resource](https://github.com/my-org/my-generator/blob/main/$resource) (copied as $destination)\n\n$description"
}.mkString("", "\n\n", "\n\n")
}If you want to tweak the resource's contents or paths before generating them,
you can use the same resourceTransformers we use for adding headers:
import sbt._
import sbt.Keys.streams
import com.alejandrohdezma.resource.generator.ResourceGenerator
object MyGeneratorPlugin extends AutoPlugin with ResourceGenerator[Unit] {
val generateMyFiles = taskKey[Unit] {
s"Generates the following files: ${resources.mkString(", ")}"
}
override def trigger = allRequirements
override def buildSettings = Seq(
generateMyFiles := generate((), logger = streams.value.log.info(_))
)
override def resourceTransformers = super.resourceTransformers.and {
case ((path, extras), content) if path.extension == "md" =>
"docs" / path.getFileName() -> extras -> content.replace("hate", "flowers")
}
}You can use any type-param when extending ResourceGenerator. An instance of the type
you add here must be provided when calling generate (see step 6 under
How to use this project?).
That value will then be provided to the ResourceTransformers described in
Transform resource's contents/paths and can
be used like:
import sbt._
import sbt.Keys._
import com.alejandrohdezma.resource.generator.ResourceGenerator
object MyGeneratorPlugin extends AutoPlugin with ResourceGenerator[String] {
val generateMyFiles = taskKey[Unit] {
s"Generates the following files: ${resources.mkString(", ")}"
}
override def trigger = allRequirements
override def buildSettings = Seq(
generateMyFiles := generate(
extras = name.value, logger = streams.value.log.info(_))
)
override def resourceTransformers = super.resourceTransformers.and {
case ((path, name), content) if path.extension == "md" =>
path -> name -> content.replace("{{name}}", name)
}
}You can pass a function to generate to decide when a file should be excluded,
and thus, not generated. This function receives both the final path and content
for the file (after all ResourceTransformers are applied) and returns a
Boolean. Return true when you want a file excluded.
For example if we want to exclude files based on glob patterns, we could do it like:
import java.nio.file._
import sbt._
import sbt.Keys._
import com.alejandrohdezma.resource.generator.ResourceGenerator
object MyGeneratorPlugin extends AutoPlugin with ResourceGenerator[String] {
object autoImport {
val excludedFiles = settingKey[List[String]] {
"List of glob patterns. Files matching any of the patterns in this list" +
" will be excluded from generation"
}
}
val generateMyFiles = taskKey[Unit] {
s"Generates the following files: ${resources.mkString(", ")}"
}
override def trigger = allRequirements
import autoImport._
override def buildSettings = Seq(
excludedFiles := Nil,
generateMyFiles := generate(
extras = name.value,
excludeFile = globPatterns.value,
logger = streams.value.log.info(_)
)
)
private val globPatterns = Def.setting {
val fileSystem = FileSystems.getDefault()
val matchers = excludedFiles.value
.map("glob:" + _)
.map(fileSystem.getPathMatcher(_))
(path: Path, _: String) => matchers.find(_.matches(path)).nonEmpty
}
}There could be a case where you want to use your generator outside an SBT project. It is a very simple task.
1 - Add a new Main file along with your MyGenerator
object Main extends App {
MyGeneratorPlugin.generate(())
}2 - Once you have published your artifact, you can run it with coursier:
cs launch --sbt-plugin my.org:my-generator:1.0.0
