Or, otherwise know as: SELinux and Silent Denials.
Sometimes when troubleshooting SELinux issues, you will have added new policies for each of the denial causes written to the audit.log, but SELinux will still be denying access . . . and not giving you any further information about it in the audit.log.
If you are building a Java program that requires the ability to execute native commands on the machine which require sudo it requires some additional considerations other than just writing the Java code.
The problem is that sudo, by default, requires a tty for executing sudo such that a password can entered. Even if you configure sudoers to grant NOPASSWD access to a specific command you will still get the following error
When maintaining a Hadoop cluster, you will need to restart various service from time-to-time when/if you update Hadoop configurations.
I ran into a problem today with Ambari where I wanted to do a rollling restart of all of my DataNodes, but when I clicked on the “Restart DataNodes” entry in the “Restart” drop down the dialog indicated “There are no DataNodes to do rolling restarts”.
I was having some issues with the ambari-metrics family of services on a ‘pseudo-distributed’ cluster that I have installed on my workstation.
The symptoms were:
1. Ambari indicated the following CRITICAL errors in the Ambari Dashboard under the Ambari Metrics section
Connection failed: [Errno 111] Connection refused to rchapin-wrkstn:6188
2. After attempting to restart the ambari-metrics-collector via either the Ambari Dashboard or through the commandline (# ambari-metrics-collector [stop|start]) you see the following (similar) messages in the ambari-metrics-collector.log