No documentation

[eatkins]

I'm making a small change to the sbt xMain entry and I'd like to test with this launcher. I cannot figure out how to run it however. With the regular launcher, I can just run java -jar $LAUNCHER but it seems like I have to specify the full classpath of the coursier launcher dependencies to run the coursier launcher? Is there any documentation anywhere?

[dwijnand]

https://github.com/coursier/sbt-extras is probably the easiest way to run it.

[eatkins]

I'm having a similar issue when I use sbt-extras:

xsbt -v -sbt-jar /Users/ethanatkins/.ivy2/local/io.get-coursier/sbt-launcher_2.12/1.2.17+3-59961fbe-SNAPSHOT/jars/sbt-launcher_2.12.jar 
Using sbt options defined in variable $SBT_OPTS
[residual] arg = '-XX:+HeapDumpOnOutOfMemoryError'
[residual] arg = '-XX:MaxMetaspaceSize=1g'
Detected sbt version 1.3.0
Using default jvm options
Detected Java version: 8
# Executing command line:
java
-Xms512m
-Xss2m
-jar
/Users/ethanatkins/.ivy2/local/io.get-coursier/sbt-launcher_2.12/1.2.17+3-59961fbe-SNAPSHOT/jars/sbt-launcher_2.12.jar
-XX:+HeapDumpOnOutOfMemoryError
-XX:MaxMetaspaceSize=1g

saving stty: gfmt1:cflag=4b00:iflag=6b02:lflag=5cb:oflag=3:discard=f:dsusp=19:eof=4:eol=ff:eol2=ff:erase=7f:intr=3:kill=15:lnext=16:min=1:quit=1c:reprint=12:start=11:status=14:stop=13:susp=1a:time=0:werase=17:ispeed=9600:ospeed=9600
Exception in thread "main" java.lang.NoClassDefFoundError: scala/collection/Seq
        at coursier.sbtlauncher.MainApp.main(MainApp.scala)
Caused by: java.lang.ClassNotFoundException: scala.collection.Seq
        at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:349)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
        ... 1 more

Am I doing something wrong? Is there a different option besides -sbt-jar? I also don't understand how it would work if I didn't have a locally published version of the launch jar.

[dwijnand]

It'll download the launch jar. The official sbt-extras downloads the official launch jar, while the coursier one uses this one.

[alexarchambault]

Sorry about that @eatkins. To generate a launcher from source, I do something like

$ sbt publishLocal # note the version it uses, something like 1.2.16+7-fa40d050-SNAPSHOT
$ VERSION=1.2.16+7-fa40d050-SNAPSHOT scripts/generate-csbt.sh -r ivy2Local -f
$ ./csbt # the newly generated launcher

[alexarchambault]

There's no sbt task to generate the launcher, currently. It relies on the bootstrap command of coursier, that creates a tiny JAR (a "bootstrap") that creates classloader hierarchy, with org.scala-sbt:launcher-interface in a first loader, and the rest of io.get-coursier::sbt-launcher in a loader with the first one as parent. That hierarchy is created by the --shared option passed to the coursier command in the generate-csbt.sh script.

[alexarchambault]

@eatkins @dwijnand ~/.ivy2/local/io.get-coursier/sbt-launcher_2.12/X.Y.Z-SNAPSHOT/jars/sbt-launcher_2.12.jar can't be passed to sbt-extras, it has to be the "bootstrap" generated by the generate-csbt.sh script (see my commands above).

[eatkins]

@alexarchambault thanks for the instructions. I got it working with them.