Enable Kubernetes Feature Gates / Switch Between Kubernetes Versions

[frankgreco]

Expected behavior

I expect there to be a way to enable feature gates on the Kubernetes API server. I also expected to be able to switch between Kubernetes versions.

Actual behavior

Perhaps this is possible, just not documented, but I don't know if there is a way to enable feature gates on the API server or switch between Kubernetes versions.

Information

• Full output of the diagnostics from "Diagnose & Feedback" in the menu

Docker for Mac: version: 17.12.0-ce-mac45 (a61e84b8bca06b1ae6ce058cdd7beab1520ad622)
macOS: version 10.13.2 (build: 17C88)
logs: /tmp/7F293033-1279-4E4C-A3FD-864540EA43DA/20180109-105457.tar.gz
[OK]     db.git
[OK]     vmnetd
[OK]     dns
[OK]     driver.amd64-linux
[OK]     virtualization VT-X
[OK]     app
[OK]     moby
[OK]     system
[OK]     moby-syslog
[OK]     kubernetes
[OK]     env
[OK]     virtualization kern.hv_support
[OK]     slirp
[OK]     osxfs
[OK]     moby-console
[OK]     logs
[OK]     docker-cli
[OK]     menubar
[OK]     disk

• A reproducible case if this is a bug, Dockerfiles FTW N/A
• Page URL if this is a docs issue or the name of a man page N/A

Steps to reproduce the behavior

N/A

[guillaumerose]

Unfortunately not for the moment. We will update to 1.9 in the next release if everything goes well.

[frankgreco]

@guillaumerose is there a somewhere I can track release dates (e.g. expected date the next release will occur). Also, which feature gates do you enabled on the apiserver by default

[guillaumerose]

We follow the same release dates as docker-ce. Every rc goes to edge channel. You can expect 2-3 releases per month.

We use default feature gates of kubeadm. The list is here: https://github.com/kubernetes/kubernetes/blob/master/cmd/kubeadm/app/features/features.go#L49

[docker-robott]

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/lifecycle stale

[frankgreco]

/remove-lifecycle stale

[frankgreco]

@guillaumerose should this issue still be in triage mode? Is this a feature that is planning on being implemented in the future?

[guillaumerose]

For the moment, we are focusing on the upgrade to 1.10.
I believe at some point you will be able to customize the kubeadm MasterConfiguration that we use. But not in a near future, sorry :/

/lifecycle frozen

[mohnishkodnani]

any updates on this, i wanted to enable a feature-gate for 1.10

[Venryx]

Any update or workaround for this a couple years later?

It'd be quite useful for enabling feature-gate flags, eg. for enabling Ephemeral Containers for easier pod debugging.

EDIT: Also noticed this issue, which seems related: #2771

[Venryx]

Several hours later, and I finally found a way to enable Kubernetes feature-gates in Docker Desktop.

See this stack-overflow answer for the painful story of my path toward finding out how.

TL;DR

Steps:

1. Open the [...]/kubeadm/manifests folder, in the Docker filesystem. (on Windows, navigate Windows Explorer to: \\wsl$\docker-desktop-data\version-pack-data\community\kubeadm\manifests)
2. Open the kube-controller-manager.yaml, kube-apiserver.yaml, and kube-scheduler.yaml files, adding the line below:

spec:
  containers:
  - command:
    [...]
    - --feature-gates=EphemeralContainers=true     <-- add this line (or whatever feature-gate flags you need)

3. Restart Docker Desktop.