sbt-global-plugin.md

Instructions on how to reproduce sbt global plugin reload bug. Related links:

https://groups.google.com/forum/?hl=en&fromgroups=#!topic/simple-build-tool/x33MRCzNpww sbt/sbt#272

Directory and File Structure

~/SbtHome/                      # used as sbt.global.base
    plugins/
        plugins.sbt             # should be empty at beginning

~/SbtProj                       # the empty project we'll test on
    project/
        Build.scala             # build definition; should be .scala file, don't use build.sbt
    sbt-launcher-script.sh      # launcher script

sbt-lanucher-script.sh

#!/bin/sh
SBT_OPTS='-Dsbt.global.base=/Users/orr/SbtHome/ '$SBT_OPTS
exec java -Xmx512M ${SBT_OPTS} -XX:MaxPermSize=512M -jar /usr/local/Cellar/sbt/0.12.2/libexec/sbt-launch.jar "$@"

Notice that the -Dsbt.global.base param value has my absolute path, don't forget to change it accordingly.

Build.scala

Just a simple empty project:

import sbt._
import sbt.Keys._

object MyBuild extends Build {
  lazy val mySettings = Defaults.defaultSettings ++ Seq(
    name := "my-test-proj",
    organization := "com.example",
    version := "0.1.0-SNAPSHOT")

  lazy val proj = Project("my-test-proj", file("."), settings = mySettings)
}

Reproduction Sequence

1. Make sure you have the above file/folder structure and that plugins.sbt is empty.

2. Enter SbtProj/ folder, start sbt with the custom launch script once, and then exit sbt:

cd SbtProj/
chmod +x sbt-launcher-script.sh
./sbt-launcher-script.sh

Output from running launcher script:

Getting net.java.dev.jna jna 3.2.3 ...
:: retrieving :: org.scala-sbt#boot-jna
    confs: [default]
	1 artifacts copied, 0 already retrieved (838kB/10ms)
Getting org.scala-sbt sbt 0.12.2 ...
:: retrieving :: org.scala-sbt#boot-app
	confs: [default]
	40 artifacts copied, 0 already retrieved (8381kB/46ms)
Getting Scala 2.9.2 (for sbt)...
:: retrieving :: org.scala-sbt#boot-scala
	confs: [default]
	4 artifacts copied, 0 already retrieved (20090kB/44ms)
[info] Loading global plugins from /Users/orr/SbtHome/plugins
[info] Updating {file:/Users/orr/SbtHome/plugins/}default-9f82cf...
[info] Resolving org.scala-sbt#precompiled-2_10_0;0.12.2 ...
[info] Done updating.
[info] Loading project definition from /Users/orr/SbtProj/project
[info] Updating {file:/Users/orr/SbtProj/project/}default-2448b4...
[info] Resolving org.scala-sbt#precompiled-2_10_0;0.12.2 ...
[info] Done updating.
[info] Compiling 1 Scala source to /Users/orr/SbtProj/project/target/scala-2.9.2/sbt-0.12/classes...
[info] Set current project to my-test-proj (in build file:/Users/orr/SbtProj/)
>

And exit sbt:

> exit

3. Now, after the project has been opened once in sbt, edit global plugins file, found at SbtHome/plugins/plugins.sbt to include some plugin:

addSbtPlugin("com.github.mpeltonen" % "sbt-idea" % "1.1.0")

It doesn't matter which plugin we use. In this example we use sbt-igea, which we expect will add the command gen-idea.

4. Relaunch sbt using the same script as before:

./sbt-launcher-script.sh

Output from launching sbt again:

[info] Loading global plugins from /Users/orr/SbtHome/plugins
[info] Updating {file:/Users/orr/SbtHome/plugins/}default-9f82cf...
[info] Resolving org.scala-sbt#precompiled-2_10_0;0.12.2 ...
[info] Done updating.
[info] Loading project definition from /Users/orr/SbtProj/project
[info] Set current project to my-test-proj (in build file:/Users/orr/SbtProj/)
> 

Notice that sbt doesn't complain about a plugin not found, or anything like that.

5. Try to use the newly should-be-available gen-idea command:

> gen-idea
[error] Not a valid command: gen-idea
[error] Expected '/'
[error] Expected ':'
[error] Not a valid key: gen-idea
[error] gen-idea
[error]         ^
> 

As we can see, even tho we added the plugin, the command isn't available.

6. Enter the "plugins" project (the project/ project), clean it, and return:

> reload plugins
[info] Loading global plugins from /Users/orr/SbtHome/plugins/project
[info] Updating {file:/Users/orr/SbtHome/plugins/project/}default-aea1cb...
[info] Resolving org.scala-sbt#precompiled-2_10_0;0.12.2 ...
[info] Done updating.
[info] Loading global plugins from /Users/orr/SbtHome/plugins
[info] Loading project definition from /Users/orr/SbtProj/project
> clean
[success] Total time: 0 s, completed Jan 31, 2013 2:46:38 PM
> reload return
[info] Loading global plugins from /Users/orr/SbtHome/plugins/project
[info] Loading global plugins from /Users/orr/SbtHome/plugins
[info] Loading project definition from /Users/orr/SbtProj/project
[info] Updating {file:/Users/orr/SbtProj/project/}default-2448b4...
[info] Resolving org.scala-sbt#precompiled-2_10_0;0.12.2 ...
[info] Done updating.
[info] Compiling 1 Scala source to /Users/orr/SbtProj/project/target/scala-2.9.2/sbt-0.12/classes...
[info] Set current project to my-test-proj (in build file:/Users/orr/SbtProj/)
> 

7. Now, after cleaning the project/ project, try to use the gen-idea command again:

> gen-idea
[info] Trying to create an Idea module my-test-proj
[info] Updating {file:/Users/orr/SbtProj/}my-test-proj...
[info] Resolving org.scala-lang#scala-library;2.9.2 ...
[info] Done updating.
[info] Resolving org.scala-lang#scala-library;2.9.2 ...
[info] Excluding folder target
[info] Created /Users/orr/SbtProj/.idea/IdeaProject.iml
[info] Created /Users/orr/SbtProj/.idea
[info] Excluding folder /Users/orr/SbtProj/target
[info] Created /Users/orr/SbtProj/.idea_modules/my-test-proj.iml
[info] Created /Users/orr/SbtProj/.idea_modules/my-test-proj-build.iml
> 

Conclusion

So there you have it – after adding a global plugin, it's tasks/commands aren't available to an existing project which has a .scala build definition. Only reloading, cleaning and returning the plugins project for that project, makes the new tasks/commands available.