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Update safely-drain-node.md

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@ -98,8 +98,8 @@ You should first be familiar with using [Kubernetes language clients](/docs/task
The eviction subresource of a The eviction subresource of a
pod can be thought of as a kind of policy-controlled DELETE operation on the pod pod can be thought of as a kind of policy-controlled DELETE operation on the pod
itself. To attempt an eviction (perhaps more REST-precisely, to attempt to itself. To attempt an eviction (perhaps more REST-precisely, to attempt to
*create* an eviction), you POST an attempted operation. Here's an example: *create* an eviction), you POST an attempted operation. Here's an example:
```json ```json
{ {
@ -123,7 +123,7 @@ The API can respond in one of three ways:
- If the eviction is granted, then the pod is deleted just as if you had sent - If the eviction is granted, then the pod is deleted just as if you had sent
a `DELETE` request to the pod's URL and you get back `200 OK`. a `DELETE` request to the pod's URL and you get back `200 OK`.
- If the current state of affairs wouldn't allow an eviction by the rules set - If the current state of affairs wouldn't allow an eviction by the rules set
forth in the budget, you get back `429 Too Many Requests`. This is forth in the budget, you get back `429 Too Many Requests`. This is
typically used for generic rate limiting of *any* requests, but here we mean typically used for generic rate limiting of *any* requests, but here we mean
that this request isn't allowed *right now* but it may be allowed later. that this request isn't allowed *right now* but it may be allowed later.
Currently, callers do not get any `Retry-After` advice, but they may in Currently, callers do not get any `Retry-After` advice, but they may in
@ -131,21 +131,21 @@ The API can respond in one of three ways:
- If there is some kind of misconfiguration, like multiple budgets pointing at - If there is some kind of misconfiguration, like multiple budgets pointing at
the same pod, you will get `500 Internal Server Error`. the same pod, you will get `500 Internal Server Error`.
For a given eviction request, there are two cases. For a given eviction request, there are two cases:
- There is no budget that matches this pod. In this case, the server always - There is no budget that matches this pod. In this case, the server always
returns `200 OK`. returns `200 OK`.
- There is at least one budget. In this case, any of the three above responses may - There is at least one budget. In this case, any of the three above responses may
apply. apply.
In some cases, an application may reach a broken state where it will never return anything In some cases, an application may reach a broken state where it will never return anything
other than 429 or 500. This can happen, for example, if the replacement pod created by the other than 429 or 500. This can happen, for example, if the replacement pod created by the
application's controller does not become ready, or if the last pod evicted has a very long application's controller does not become ready, or if the last pod evicted has a very long
termination grace period. termination grace period.
In this case, there are two potential solutions: In this case, there are two potential solutions:
- Abort or pause the automated operation. Investigate the reason for the stuck application, and restart the automation. - Abort or pause the automated operation. Investigate the reason for the stuck application, and restart the automation.
- After a suitably long wait, `DELETE` the pod instead of using the eviction API. - After a suitably long wait, `DELETE` the pod instead of using the eviction API.
Kubernetes does not specify what the behavior should be in this case; it is up to the Kubernetes does not specify what the behavior should be in this case; it is up to the