Details
Minor Description
Karaf supplies an example systemd file: https://github.com/apache/karaf/blob/master/assemblies/features/base/src/main/resources/resources/bin/contrib/karaf-service-template.systemd
For our solution we use a similar systemd service file. However we noticed that when stopping the service, it's always left in a "failed" state:
root@vagrant:/opt/instana/agent# systemctl stop instana-agent root@vagrant:/opt/instana/agent# systemctl status instana-agent ● instana-agent.service - "Instana(tm) agent." Loaded: loaded (/lib/systemd/system/instana-agent.service; enabled; vendor preset: enabled) Active: failed (Result: signal) since Tue 2020-12-15 20:29:44 UTC; 2s ago Process: 5461 ExecStop=/opt/instana/agent/bin/karaf stop (code=exited, status=0/SUCCESS) Process: 5371 ExecStart=/opt/instana/agent/bin/karaf daemon (code=killed, signal=KILL) Main PID: 5371 (code=killed, signal=KILL)
This is not due to the way the systemd service is being stopped, but rather due to how the "stop" command is handled internally. Following the execution path from the "karaf" script, this eventually leads to https://github.com/apache/karaf/blob/bb175f9c613921a20e017c343e6b978a3e80c80e/util/src/main/java/org/apache/karaf/jpm/impl/ProcessImpl.java#L84
ret = ScriptUtils.executeProcess(new java.lang.ProcessBuilder("kill", "-9", Integer.toString(pid)));
Instead of doing a hard `kill -9`, it would be much nicer to first execute a 'kill', followed by checking if the process nicely shuts down and if not executing the 'kill -9'.