I finally used Packer to build an AMI based on Amazon Linux 2 to act as as agent. Yesterday, the builds began failing with a Java stack trace.
Turns out the EC2 instance starts, and in parallel the Jenkins agent begins and an auto-upgrade of openjdk kicked off. Further instructions failed. Rebuild the AMI and the new agent worked a treat.
Is there a way of avoiding this problem by preventing Jenkins from launching the agent until the boot steps are complete? I cannot be the first to encounter this issue :-)
Thanks,
James