with strict eviction policy the descheduler only evict pods if the pod
contains a request for the given threshold. for example, if using a
threshold for an extended resource called `example.com/gpu` only pods
who request such a resource will be evicted.
when calculating the average an applying the deviations it would be nice
to also see the assessed values.
this commit makes the descheduler logs these values when using level 3.
In some cases it might be usefull to limit how many evictions per a
domain can be performed. To avoid burning the whole per descheduling
cycle budget. Limiting the number of evictions per node is a
prerequisite for evicting pods whose usage can't be easily subtracted
from overall node resource usage to predict the final usage. E.g. when a
pod is evicted due to high PSI pressure which takes into account many
factors which can be fully captured by the current predictive resource
model.
This commit adds a sample plugin implementation as follow:
This directory provides an example plugin for the Kubernetes Descheduler,
demonstrating how to evict pods based on custom criteria. The plugin targets
pods based on:
* **Name Regex:** Pods matching a specified regular expression.
* **Age:** Pods older than a defined duration.
* **Namespace:** Pods within or outside a given list of namespaces (inclusion
or exclusion).
To incorporate this plugin into your Descheduler build, you must register it
within the Descheduler's plugin registry. Follow these steps:
1. **Register the Plugin:**
* Modify the `pkg/descheduler/setupplugins.go` file.
* Add the following registration line to the end of the
`RegisterDefaultPlugins()` function:
```go
pluginregistry.Register(
example.PluginName,
example.New,
&example.Example{},
&example.ExampleArgs{},
example.ValidateExampleArgs,
example.SetDefaults_Example,
registry,
)
```
2. **Generate Code:**
* If you modify the plugin's code, execute `make gen` before rebuilding the
Descheduler. This ensures generated code is up-to-date.
3. **Rebuild the Descheduler:**
* Build the descheduler with your changes.
Configure the plugin's behavior using the Descheduler's policy configuration.
Here's an example:
```yaml
apiVersion: descheduler/v1alpha2
kind: DeschedulerPolicy
profiles:
- name: LifecycleAndUtilization
plugins:
deschedule:
enabled:
- Example
pluginConfig:
- name: Example
args:
regex: ^descheduler-test.*$
maxAge: 3m
namespaces:
include:
- default
```
- `regex: ^descheduler-test.*$`: Evicts pods whose names match the regular
expression `^descheduler-test.*$`.
- `maxAge: 3m`: Evicts pods older than 3 minutes.
- `namespaces.include: - default`: Evicts pods within the default namespace.
This configuration will cause the plugin to evict pods that meet all three
criteria: matching the `regex`, exceeding the `maxAge`, and residing in the
specified namespace.
When the feature is enabled each pod with descheduler.alpha.kubernetes.io/request-evict-only
annotation will have the eviction API error examined for a specific
error code/reason and message. If matched eviction of such a pod will be interpreted
as initiation of an eviction in background.
