NodeLocal DNS container hung on SIGTERM
- Dominant language
- Go
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Description
We are still hitting the same problem reported by https://github.com/kubernetes/dns/issues/394. The test failure occurred on Kubernetes version 1.21 with NodeLocal DNS cache version 1.17.3.
To recap, NodeLocal DNS container occasionally hangs on termination causing Kubernetes to kill the container using SIGTERM after the grace period has expired. This leaves left over iptables rules on the node thus breaking DNS resolution. Our theory is that there is iptables lock contention between NodeLocal DNS, Calico and/or Kubernetes.
Contributor guide
Research direction
Start with the linked kubernetes/dns issue 394 and compare the Kubernetes 1.21 and NodeLocal DNS 1.17.3 failure described here. Investigate SIGTERM termination alongside iptables lock contention involving NodeLocal DNS, Calico, and Kubernetes; done means the container exits without leaving rules that break DNS resolution.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- go
- Domain
- networking
- Issue type
- Bug
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Quiet
- Clarity
- Needs clarification
- Newbie friendliness
- 30/100