[HBASE-19424] Metrics servlet throws NPE

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.4.0
• Fix Version/s: 1.3.2, 1.4.1, 2.0.0-beta-1, 2.0.0, 1.2.7
• Assignee: Toshihiro Suzuki
• Reporter: Andrew Kyle Purtell
• Created: 05/Dec/17 00:09
• Updated: 01/Feb/19 19:57
• Resolved: 08/Jan/18 23:19

Description

In branch-1 at least we put up a servlet on "/metrics" that is Hadoop's MetricsServlet. However HBase users are expected to pick up metrics via "/jmx". We don't mention "/metrics" or link to it on the UI. If you attempt to access "/metrics" with head of branch-1 it errors out due to a NPE

2017-12-04 16:06:37,403 ERROR [1874557409@qtp-1910896157-3] mortbay.log: /metrics
java.lang.NullPointerException
	at org.apache.hadoop.http.HttpServer2.isInstrumentationAccessAllowed(HttpServer2.java:1049)
	at org.apache.hadoop.metrics.MetricsServlet.doGet(MetricsServlet.java:109)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)