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docs: Update self-hosted proposal

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Derek Parker 2016-05-02 12:09:37 -07:00
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docs/proposals/self-hosted-kubelet.md
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@ -31,7 +31,9 @@ Documentation for other releases can be found at
## Abstract ## Abstract
In a self-hosted Kubernetes deployment, we have the initial bootstrap problem. In a self-hosted Kubernetes deployment (see (this
comment)[https://github.com/kubernetes/kubernetes/issues/246#issuecomment-64533959]
for background on self hosted kubernetes), we have the initial bootstrap problem.
When running self-hosted components, there needs to be a mechanism for pivoting When running self-hosted components, there needs to be a mechanism for pivoting
from the initial bootstrap state to the kubernetes-managed (self-hosted) state. from the initial bootstrap state to the kubernetes-managed (self-hosted) state.
In the case of a self-hosted kubelet, this means pivoting from the initial In the case of a self-hosted kubelet, this means pivoting from the initial
@ -40,7 +42,9 @@ to the node.
This proposal presents a solution to the kubelet bootstrap, and assumes a This proposal presents a solution to the kubelet bootstrap, and assumes a
functioning control plane (e.g. an apiserver, controller-manager, scheduler, and functioning control plane (e.g. an apiserver, controller-manager, scheduler, and
etcd cluster), and a kubelet that can securely contact the API server. etcd cluster), and a kubelet that can securely contact the API server. This
functioning control plane can be temporary, and not necessarily the "production"
control plane that will be used after the initial pivot / bootstrap.
## Background and Motivation ## Background and Motivation
@ -71,9 +75,10 @@ explained in detail below.
## Proposal ## Proposal
We propose adding a new flag to the kubelet, the `--bootstrap` flag, which is We propose adding a new flag to the kubelet, the `--bootstrap` flag, which is
assumed to be used in conjunction with the `--lock-file` flag. When the assumed to be used in conjunction with the `--lock-file` flag. The `--lock-file`
`--bootstrap` flag is provided, after the kubelet acquires the file lock, it flag is used to ensure only a single kubelet is running at any given time during
will begin asynchronously waiting on this pivot process. When the `--bootstrap` flag is provided, after the kubelet
acquires the file lock, it will begin asynchronously waiting on
[inotify](http://man7.org/linux/man-pages/man7/inotify.7.html) events. Once an [inotify](http://man7.org/linux/man-pages/man7/inotify.7.html) events. Once an
"open" event is received, the kubelet will assume another kubelet is attempting "open" event is received, the kubelet will assume another kubelet is attempting
to take control and will exit by calling `exit(0)`. to take control and will exit by calling `exit(0)`.
@ -139,9 +144,10 @@ Various similar approaches have been discussed
[here](https://github.com/kubernetes/kubernetes/issues/246#issuecomment-64533959) [here](https://github.com/kubernetes/kubernetes/issues/246#issuecomment-64533959)
and and
[here](https://github.com/kubernetes/kubernetes/issues/23073#issuecomment-198478997). [here](https://github.com/kubernetes/kubernetes/issues/23073#issuecomment-198478997).
This also relies on the kubelet being able to be run inside a container, more Other discussion around the kubelet being able to be run inside a container is
discussion on that is [here](https://github.com/kubernetes/kubernetes/issues/4869). Note this isn't a
[here](https://github.com/kubernetes/kubernetes/issues/4869). strict requirement as the kubelet could be run in a chroot jail via rkt fly or
other such similar approach.
Additionally, [Taints and Additionally, [Taints and
Tolerations](../../docs/design/taint-toleration-dedicated.md), whose design has Tolerations](../../docs/design/taint-toleration-dedicated.md), whose design has