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tlathm

Member

Registered: 2017-11-25

Posts: 103  

Strange service issues causes by stray dhclient process

We ran into a some strange issues with a customer that appear to have been caused by a stray dhclient process. I've been able to figure out why that process was running and how to prevent that. However I'm trying to determine if that process may have been causing other issues we had. This is with Devuan 1.0 Jessie by the way. Also note that we're not using network manager.

The symptom we had was that some services were getting arbitrarily stopped. Not crashing, but seeming stopped intentionally. This included some of our own services and on one occasion, mysql. In the case of the latter, the mysql log clearly showed a clean shutdown that was not initiated by anyone as far as we know.

We deliver our product on a VM configured for DHCP by default. In this case there was either no DHCP server available, or possibly it refused to give us a lease, so the network start timed out. That in and of itself wasn't an issue. Our install process configures a static IP etc as specified by the customer. What I discovered was that we were writing a new /etc/network/interfaces file before stopping the network...which prevented the stop process from knowing that there was a dhclient process to kill. We've since changed that.

While that process was running as it turned out, the /var/log/syslog file showed evidence that we were getting repeatedly hit with DHCPDISCOVER requests from that processes...at least one a second actually. While I'm not 100% clear on this, I believe there were signs in /var/log/messages that this may have been causing the interface to go up and down occasionally. Unfortunately we've yet to find out whether the services have properly kept running since we killed that process.

So my big question is this: Could that process repeatedly trying to get an IP for that statically configured adapter somehow cause services to stop like that?...possibly due to the LSB dependencies or the like? We've certainly never seen anything remotely like this before.

Thanks!
Tom