Name: A Debugging Journey from Coredns to Coreutils - Akhil Mohan & Humble Devassy Chirammal, VMware by Broadcom
Start: 2024-12-12T11:30:00+0530
End: 2024-12-12T12:05:00+0530

In-person
11-12 December
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Thursday December 12, 2024 11:30am - 12:05pm IST

Room 4

It all started when CoreDNS pods entered a crash loop backoff state soon after the cluster was deployed. The only change was an unprivileged execution desired in the latest coreDNS image. The issue occurred only in worker nodes, not in control plane nodes, and refreshing the image by deleting and pulling it again resolved the issue. It happened in one OS distribution flavor but not in another. We investigated Docker build, setcap, and libc, and found that the required capability was missing in nodes during the issue. The stack was complex, involving FIPS/CGO, build system, runtime configuration, and binary packaging in OVA. Debugging included CoreDNS binary, containerd, runc, SELinux, AppArmor, Photon OS, and the kernel... lots of learning which could be useful for many developers/admins or cluster operators to debug unprivileged pod execution. Finally, we discovered something interesting in the bootstrapping scripts. Let's debug.

Speakers

Akhil Mohan

Software Engineer, VMware by Broadcom

Akhil works as a Software Engineer at VMware by Broadcom. An active contributor to projects in cloud native and container ecosystem. Akhil is a maintainer of containerd, and the kubernetes publishing-bot sub project. He works mostly on container runtimes and kubernetes sig-node a... Read More →

Humble Chirammal

R&D Engineer, VMware by Broadcom

Humble is part of VMware Tanzu Open Source Engineering. He is the tech lead for k8s and other core components to deliver successful LTS releases. He has more than 17 years of experience that includes extensive work in Openshift engineering & releases. He has led SDS based products... Read More →

Thursday December 12, 2024 11:30am - 12:05pm IST
Room 4

Operations + Performance

Content Experience Level Intermediate

KubeCon + CloudNativeCon India 2024

Akhil Mohan

Humble Chirammal

Attendees (1)

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