FAQ
Direct former README import (possibly not up-to-date)
Even though the coursier sbt plugin is enabled and some coursier* keys can be found from the sbt prompt, dependency resolution seems still to be handled by sbt itself. Why?
Check that the default sbt settings (sbt.Defaults.defaultSettings) are not manually added to your project.
These define commands that the coursier sbt plugin overrides. Adding them again erases these overrides,
effectively disabling coursier.
With spark >= 1.5, I get some NoVerifyError exceptions related to jboss/netty. Why?
This error originates from the org.jboss.netty:netty:3.2.2.Final dependency to be put in the classpath.
Exclude it from your spark dependencies with the exclusion org.jboss.netty:netty.
Coursier tries to follow the Maven documentation to build the full dependency set, in particular
some points about dependency exclusion.
Inspecting the org.apache.spark:spark-core_2.11:1.5.2 dependency graph shows that spark-core
depends on org.jboss.netty:netty:3.2.2.Final via the following path: org.apache.spark:spark-core_2.11:1.5.2 ->
org.tachyonproject:tachyon-client:0.7.1 -> org.apache.curator:curator-framework:2.4.0 ->
org.apache.zookeeper:zookeeper:3.4.5 -> org.jboss.netty:netty:3.2.2.Final. Even though
spark-core tries to exclude org.jboss.netty:netty to land in its classpath via some other dependencies
(e.g. it excludes it via its dependencies towards org.apache.hadoop:hadoop-client and org.apache.curator:curator-recipes),
it does not via the former path. So it depends on it according to the
Maven documentation.
This is likely unintended, as it leads to exceptions like
java.lang.VerifyError: (class: org/jboss/netty/channel/socket/nio/NioWorkerPool, method: createWorker signature: (Ljava/util/concurrent/Executor;)Lorg/jboss/netty/channel/socket/nio/AbstractNioWorker;) Wrong return type in function
Excluding org.jboss.netty:netty from the spark dependencies fixes it.
On first launch, the coursier launcher downloads a 1.5+ MB JAR. Is it possible to have a standalone launcher, that would not need to download things on first launch?
Run scripts/generate-launcher.sh -s from the root of the coursier sources. That will generate a new (bigger) coursier launcher, that needs not to download anything on first launch.
How can the launcher be run on Windows, or manually with the java program?
Download it from the same link as the command above. Then run from a console, in the directory where the coursier launcher is,
> java -noverify -jar coursier
The -noverify option seems to be required after the proguarding step of the main JAR of coursier.
How to enable sandboxing?
Set the COURSIER_CACHE prior to running coursier or sbt, like
$ COURSIER_CACHE=$(pwd)/.coursier-cache coursier
or
$ COURSIER_CACHE=$(pwd)/.coursier-cache sbt