Adding support for GKE in KubeConfig

[bchapuis]

It is possible to connect to a remote kubernetes cluster hosted by google (GKE) with the following command, which automatically updates the .kube/config file:

gcloud container clusters get-credentials CLUSTER_NAME --zone ZONE_NAME --project PROJECT_NAME

It would be nice if this kind of configuration was supported by the java client out of the box.

[brendandburns]

This would involve integrating the GKE library into this library... It feels kind of out-of scope for the client library to do this.

@lwander @mbohlool what do you think?

I suppose we could add a cloudprovider package or somesuch...

[bergman]

I can see how this is out of scope for the client and should perhaps be handled by some plugin for each different type of auth or cloud provider. On the other hand, opening up to another type of authentication and configuration besides reading ~/.kube/config would be great. Basically being able to from my application connect to a different master without having to instantiate a KubeConfig object which is quite opaque to me.

[mbohlool]

Some configurations in kubeconfig require the client to run a refresh command. GCP provider is one (and the only one I know) of them. I think it is resonable to support use case of refreshing token if it is already in kubeconfig file, but retrieving configuration from different client providers is out of the scope of client libraries and should be a separate library/command. to @bergman I think it is useful to generalize the configuration object (if it is not already) to be able to support other auth providers.

[brendandburns]

@bergman just for completeness, there are a wide variety of ways to load configs other than ~/.kube/config.

The easiest is to set the export KUBECONFIG=/some/path/to/config environment variable to some other config file, and the code will automatically pick up from that .

But there are other programatic approaches also, for example:
https://github.com/kubernetes-client/java/blob/master/util/src/main/java/io/kubernetes/client/util/Config.java#L106

Hope that helps.
--brendan

[brendandburns]

I'm going to close this, since it's out of scope for the library.

[bergman]

@brendandburns all of those options require a file (could be virtual I guess and made programmatically within your code, but still) in the format of ~/.kube/config or KubeConfig. What I'm requesting is a way to instantiate a KubeConfig object from something other than a file such that I can programmatically switch to some other cluster/master etc based on e.g. runtime config of my application. Sure, I could shell out to whatever generates my ~/.kube/config and configure a new client from that but that's not a good experience for anyone.

Even if you do open up to some plugins for doing auth and configuration for different providers, they will need some API to do so and generating a virtual file to do that is not great.

Agree on closing this issue as it relates only to GKE. Please point me to where we can have the more general discussion on making it simpler to use with any provider.

[brendandburns]

@bergman I think I must not understand, you can instantiate a KubeConfig object just like any other Java object:

KubeConfig kc = new KubeConfig(...);
...

See:
https://github.com/kubernetes-client/java/blob/master/util/src/main/java/io/kubernetes/client/util/KubeConfig.java#L91

Is this because there aren't setters for the KubeConfig object? Or is it because the objects within the config aren't strongly typed?

I can see an argument for both of those features.

If you want one (or both) please open separate issues like "make KubeConfig sub-objects strongly typed" or somesuch...

Thanks!

[brendandburns]

@bergman friendly ping for more info if you want...

thanks!

[bergman]

@brendandburns thanks for getting back to me! I'm on holidays so sorry for the delayed response. You're right, it's possible to instantiate a KubeConfig but as you noted, it's not especially clear how with those untyped collections. I will take another stab at this when I get back to work next week.

Something that would allow me to do something like this is what I'm after:
https://github.com/spotify/styx/blob/c0654ac66a74692ffbc6974b824f3d763a6e6bc4/styx-scheduler-service/src/main/java/com/spotify/styx/StyxScheduler.java#L693-L699

[brendandburns]

Closing in favor of #168 that better captures the intent of this issue.