You'd expect this class to be available on a system supporting WASB...
Could I add some java options somewhere so it can find this class?
Also strange is that when I look at the setup of a HDInsight cluster, it's setup just like the default setup by Cloudbreak and there it simply works, the spark history server doesn't complain about the default hdfs:///spark-history uri
I think this is an Ambari bug. You can report the issue here after you've registered: http://issues.apache.org/jira/browse/AMBARI . Also could you please accept the answer here so others can find the solution while it's beeing fixed. Thank you.