CODEWITHSUNDEEP
kubernetesetcd
Grzegorz Wilanowski
Grzegorz Wilanowski

Reputation: 150

What operating system etcd uses

I logged into Kubernetes etcd pod

kubectl exec -it -n kube-system etcd-master -- /bin/sh

I cannot figure out what OS is it.

ls does not work

sh-5.0# ls
sh: ls: command not found

cat does not work

sh-5.0# cat /etc/os-release
sh: cat: command not found

apt,yum not recognized

sh-5.0# apt
sh: apt: command not found

sh-5.0# yum
sh: yum: command not found

I can only cd and list files via pattern expansion

sh-5.0# cd /etc
sh-5.0# echo *
debian_version default dpkg group host.conf hostname hosts issue issue.net kubernetes network nsswitch.conf os-release passwd profile.d protocols resolv.conf rpc services skel ssl update-motd.d

sh-5.0# echo `<os-release`
PRETTY_NAME="Distroless" NAME="Debian GNU/Linux" ID="debian" VERSION_ID="9" VERSION="Debian GNU/Linux 9 (stretch)" HOME_URL="https://github.com/GoogleContainerTools/distroless" SUPPORT_URL="https://github.com/GoogleContainerTools/distroless/blob/master/README.md" BUG_REPORT_URL="https://github.com/GoogleContainerTools/distroless/issues/new"

What operating system is it? How to install bash here?

Upvotes: 0

Views: 330

Answers (2)

wpedrak
wpedrak

Reputation: 687

Judging by PRETTY_NAME, it's Distroless (https://github.com/GoogleContainerTools/distroless). On their README, you can read

Who uses Distroless?

  • Kubernetes, since v1.15
  • ...

Which is probably your case.

Upvotes: 0

anemyte
anemyte

Reputation: 20196

/etc/os-release states that the image is based on Distroless. The SUPPORT_URL given there explains that:

"Distroless" images contain only your application and its runtime dependencies. They do not contain package managers, shells or any other programs you would expect to find in a standard Linux distribution.

For more information, see this talk (video).

This is one of the best practices with containers to leave only what is absolutely necessary inside. You may encounter many such images and some even won't have sh in it. Moreover, root filesystem can be read only and/or the container might not have enough privileges to install things.

With all this in mind, it may be so that you will not be able to bring bash or anything else inside. Depending on your actual goal, you may:

  1. Try to copy files out of the container with kubectl cp (requires tar inside the image);
  2. Get into the host node of the container and locate container files on the host. You may as well use docker cp on the host to push bash binary inside the running container.

Upvotes: 2

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