Environment:

We have Jenkins Master and Slave architecture ( Jenkins ver. 2.150.3) on Azure

The Agent VM template is used to launch new agents based on the need.

The template does not DROP/DELETE Agent VMs (Ubuntu 16.04 LTS) instead only shuts them down so that it can bring the Agent VM back per need.

Issue : 

For the very first time, Agent VM comes to life it is able to report back to Master and jobs get executed on it.

Post "Idle Timeout" the VM is shutdown.

However, when the VMs is required to execute jobs and it comes back online, it could not connect to Master. The Agent on VM is launched though and the logs (as seen from Jenkins master console for that Agent halts as shown below)

openjdk full version "1.8.0_265-8u265-b01-0ubuntu2~16.04-b01"

<===[JENKINS REMOTING CAPACITY]===>Remoting version: 3.27

This is a Unix agent

NOTE: Relative remote path resolved to: /home/agentadmin

Evacuated stdout

 
The remoting.jar is also running on Agent VM , 
ps -ef | grep java
agentad+ 14565 9012 0 15:05 pts/1 00:00:00 grep --color=auto java
agentad+ 31253 31198 0 00:15 ? 00:04:32 java -jar remoting.jar
 
Due to the issue, the Agent is non-usable. Need your help & suggestions to resolve it