Allow Ark server to run in arbitrary namespaces

[SleepyBrett]

Currently the Ark server component assumes that it's configuration is stored in api.DefaultNamespace (heptio-ark) with no way to override. As cluster admins we put these kind of tools into a 'utils' namespace and would like to do the same for Ark.

The server component should probably assume it's configuration is stored in the namespace it's deployed in. The client would need to support a namespace flag or configuration or both.

[ncdc]

To do this, we should

1. Use the in-cluster namespace for the ark server
2. Add --namespace/-n to the ark CLI
3. Optionally have ~/.arkconfig or ~/.config/ark as a means to set the default namespace so you don't have to type --namespace all the time

[woop]

@ncdc Can I work on a PR for (1) and (2)?

[ncdc]

Definitely, thanks!

…

On Thu, Oct 12, 2017 at 4:17 AM Willem Pienaar ***@***.***> wrote: @ncdc <https://github.com/ncdc> Can I work on a PR for (1) and (2)? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#106 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAABYpvT_7qRjJHdUCuyjwlL-b73pWv0ks5srcsugaJpZM4PmMuj> .

[ncdc]

If there’s anything that you think needs discussion before coding, feel free to raise that here first.

…

On Thu, Oct 12, 2017 at 7:11 AM Andy Goldstein ***@***.***> wrote: Definitely, thanks! On Thu, Oct 12, 2017 at 4:17 AM Willem Pienaar ***@***.***> wrote: > @ncdc <https://github.com/ncdc> Can I work on a PR for (1) and (2)? > > — > You are receiving this because you were mentioned. > > > Reply to this email directly, view it on GitHub > <#106 (comment)>, or mute > the thread > <https://github.com/notifications/unsubscribe-auth/AAABYpvT_7qRjJHdUCuyjwlL-b73pWv0ks5srcsugaJpZM4PmMuj> > . >

[ncdc]

@SleepyBrett @woop just checking in - are either of you working on this? Thanks!

[woop]

@ncdc I'm not actively working on this. Bit short on time. I'll swing back when I have more free time.

[ashish-amarnath]

My approach, for the server, was to inject the namespace into the server as an environment and read the environment variable, if it exists, else use the default namespace. @ncdc Can you elaborate on "Use the in-cluster namespace for the ark server"
Is this an option for one of the kubernetes APIs? Not too familiar with using the k8s APIs.

[ncdc]

@ashish-amarnath yes, it's part of client-go. Let me see if I can dig up the exact code you'll need.

[ncdc]

@ashish-amarnath in pkg/client/client.go, replace the call to clientcmd.BuildConfigFromKubeconfigGetter with this:

clientConfig := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(
  loader,
  &clientcmd.ConfigOverrides{},
)

That gives you a clientcmd.ClientConfig, upon which you can invoke Namespace(), and that will return the pod's namespace if you're running it in a Kubernetes cluster. You'll probably need to tweak it so that there's a ClientConfig() function that returns the clientcmd.ClientConfig, and then the current Config() function can just call that, and then return the *rest.Config as it currently does. Or something like that...