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Update README directions for authenticating within a cluster #316

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Apr 25, 2018
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Update README directions for authenticating within a cluster #316

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Update README directions for authenticating within a cluster
jeremywadsack Apr 21, 2018
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Update DNS address in README for autheticating within a cluster per k…
jeremywadsack Apr 24, 2018
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28 changes: 20 additions & 8 deletions README.md
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Expand Up @@ -134,23 +134,35 @@ client = Kubeclient::Client.new(
)
```

If you are running your app using kubeclient inside a Kubernetes cluster, then you can have a bearer token file
mounted inside your pod by using a
[Service Account](https://github.com/GoogleCloudPlatform/kubernetes/blob/master/docs/design/service_accounts.md). This
will mount a bearer token [secret](https://github.com/GoogleCloudPlatform/kubernetes/blob/master/docs/design/secrets.md)
a/ `/var/run/secrets/kubernetes.io/serviceaccount/token` (see [here](https://github.com/GoogleCloudPlatform/kubernetes/pull/7101)
for more details). For example:
#### Inside a Kubernetes cluster

The recommended way to locate the apiserver within the pod is with the `kubernetes` DNS name, which resolves to a Service IP which in turn will be routed to an apiserver.
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https://kubernetes.io/docs/tasks/administer-cluster/access-cluster-api/#accessing-the-api-from-a-pod documents kubernetes.default. I suspect kubernetes works too but only from pod running in default namespace?

BTW, consider linking to that doc.

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@jeremywadsack jeremywadsack Apr 23, 2018 •
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Hmm... I found different instructions at https://kubernetes.io/docs/tasks/access-application-cluster/access-cluster/#accessing-the-api-from-a-pod (linked in the PR). Adding a link in the docs here is a good idea, but we need to decide which one is the right one. :) Reading the two, I think your link is more accurate / more recent?

On a separate note, I see that the link you shared says "Official client libraries do this automatically." I would like a feature where kubeclient can automatically authenticate itself where possible (e.g. within a cluster). However, from the discussions we've had, it sounds like you're more inclined to have authentication be explicit.

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LOL. I'm hoping to get some answers on kubernetes/kubernetes#40973.

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opened kubernetes/website#8166 to fix the docs


The recommended way to authenticate to the apiserver is with a [service account](https://kubernetes.io/docs/tasks/configure-pod-container/configure-service-account/). kube-system associates a pod with a service account and a bearer token for that service account is placed into the filesystem tree of each container in that pod at `/var/run/secrets/kubernetes.io/serviceaccount/token`.

If available, a certificate bundle is placed into the filesystem tree of each container at `/var/run/secrets/kubernetes.io/serviceaccount/ca.crt`, and should be used to verify the serving certificate of the apiserver.

For example:

```ruby
auth_options = {
bearer_token_file: '/var/run/secrets/kubernetes.io/serviceaccount/token'
}
ssl_options = {}
if File.exist?("/var/run/secrets/kubernetes.io/serviceaccount/ca.crt")
ssl_options[:ca_file] = "/var/run/secrets/kubernetes.io/serviceaccount/ca.crt"
end
client = Kubeclient::Client.new(
'https://localhost:8443/api/', 'v1', auth_options: auth_options
'https://kubernetes', 'v1', auth_options: auth_options, ssl_options: ssl_options
)
```

You can find information about tokens in [this guide](http://kubernetes.io/docs/user-guide/accessing-the-cluster/) and in [this reference](http://kubernetes.io/docs/admin/authentication/).
Finally, the default namespace to be used for namespaced API operations is placed in a file at `/var/run/secrets/kubernetes.io/serviceaccount/namespace` in each container. It is recommended that you use this namespace when issuing API commands below.

```ruby
namespace = File.read('/var/run/secrets/kubernetes.io/serviceaccount/namespace')
```
You can find information about tokens in [this guide](https://kubernetes.io/docs/tasks/access-application-cluster/access-cluster/#accessing-the-api-from-a-pod) and in [this reference](http://kubernetes.io/docs/admin/authentication/).

### Non-blocking IO

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