preStop lifecycle policy does not work due to missing sleep binary

[supernothing]

While debugging some transient DNS issues in a cluster today, I noticed the following error in the cluster event logs:

Exec lifecycle hook ([/usr/bin/sleep 15]) for Container "coredns" in Pod "coredns-coredns-8dbff79d6-kkp8n_kube-system(662883c5-3b59-46d5-9785-cb4146cdf3a6)" failed - error: rpc error: code = Unknown desc = failed to exec in container: failed to start exec "a6bf72f3d8f69ed29f82c49d1d2b3f1431ef56bd95de14bef845556fcfcfa93b": OCI runtime exec failed: exec failed: container_linux.go:380: starting container process caused: exec: "/usr/bin/sleep": stat /usr/bin/sleep: no such file or directory: unknown, message: ""

I believe this change to the coredns base image led to the preStop lifecycle hook to no longer function correctly: coredns/coredns@a77d983 . Since /usr/bin/sleep doesn't exist, the coredns pod is terminated immediately instead of respecting the preStopSleep value.

I worked around this issue by building my own coredns image that had /usr/bin/sleep. Not sure the best way to fix this given the empty base image, but wanted to report it in case anyone else was experiencing the same issue.

[Kyslik]

You can build your own with following DF:

FROM debian:11-slim AS tools

RUN apt update && apt upgrade -y

# For original Dockerfile
# See https://github.com/coredns/coredns/blob/master/Dockerfile
FROM docker.io/coredns/coredns:1.9.3

COPY --from=tools /bin/sleep /usr/bin/sleep
COPY --from=tools /lib/x86_64-linux-gnu/libc.so.6 /lib/x86_64-linux-gnu/libc.so.6
COPY --from=tools /lib64/ld-linux-x86-64.so.2 /lib64/ld-linux-x86-64.so.2

[hagaibarel]

The preStopSleep option has been removed from the chart in #136 as the sleep binary is no longer present in the image