Source: puppet.com
Solving critical Windows services restart during Puppet agent upgradesCategory: Software
In this blog we’ll share the journey we went on to solve a not-so-easy customer problem: a critical Windows services restart during Puppet agent upgrades.
This troubleshooting journey goes from analyzing Windows installer logs, to using undocumented Windows API calls, and back to the Windows installer logs, until we eventually found a solution. On Puppet Enterprise (PE) deployments, each Windows agent runs a service to allow execution of various actions on remote nodes — the pxp-agent.
The problem varies between Windows versions, but generally it looks like this: The reason behind this is that the puppet-agent package upgrades the nssm.exe file that is currently loaded in the Event Log service process image: This leads to an Event Log service restart that also restarts other services registered as Event Log message sources, including critical services like DHCP server, DHCP client, etc.
Not registering nssm.exe as an Event Log message source was our first step, so that NSSM upgrades would no longer trigger a restart of the Event Log service.
This troubleshooting journey goes from analyzing Windows installer logs, to using undocumented Windows API calls, and back to the Windows installer logs, until we eventually found a solution. On Puppet Enterprise (PE) deployments, each Windows agent runs a service to allow execution of various actions on remote nodes — the pxp-agent.
The problem varies between Windows versions, but generally it looks like this: The reason behind this is that the puppet-agent package upgrades the nssm.exe file that is currently loaded in the Event Log service process image: This leads to an Event Log service restart that also restarts other services registered as Event Log message sources, including critical services like DHCP server, DHCP client, etc.
Not registering nssm.exe as an Event Log message source was our first step, so that NSSM upgrades would no longer trigger a restart of the Event Log service.
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