Proposal: Support Descheduler Extender Plugin #1726
Description
- To enhance flexibility, Descheduler can support an Extender plugin (like upstream scheduler) allowing external services to make decision on whether a pod can be evicted. This enables integration with custom logic without modifying Descheduler code.
apiVersion: "descheduler/v1alpha2"
kind: "DeschedulerPolicy"
profiles:
- name: default
pluginConfig:
- ...
- name: "ExternalDecision"
args:
# for the external HTTP service (Extender)
extender:
# Base URL of the external service
urlPrefix: "https://127.0.0.1:8080"
# endpoint path to call (e.g., POST <urlPrefix>/<decisionVerb>)
decisionVerb: "evict"
# Whether to ignore failures (timeout, network error, non-200 response)
ignorable: true # Required: true/false
# Timeout for the HTTP request
httpTimeout: 5s # Required: e.g., "5s"
# Enable HTTPS
enableHTTPS: true # Optional: defaults to false
# TLS configuration for verifying the server
tlsConfig:
caCertFile: "/path/to/ca.crt" # Optional: path to CA certificate
# Plugin-specific behavior
# when the extender call fails (ignored if ignorable=true)
failPolicy: "Deny" # Optional: "Allow", "Deny", "Ignore" (default: "Deny")Request:
Endpoint: POST /
Request Body (JSON):
{
"pod": { /* Full v1.Pod object */ },
"node": { /* Full v1.Node object */ }
}Response Body (JSON):
{
"allow": true, // boolean: true to allow eviction, false to block
"reason": "Pod is eligible for cost-saving migration."
}
Plugin Behavior
- Success (allow: true): Eviction pod.
- Blocked (allow: false): Pod is skipped; reason is logged.
- Failure (timeout, error, non-200):
- If ignorable: true: Proceed as if allow: true (or respect failPolicy if implemented).
- If ignorable: false: Block eviction (allow: false), unless failPolicy overrides.
Is your feature request related to a problem? Please describe.
Describe the solution you'd like
Describe alternatives you've considered
What version of descheduler are you using?
descheduler version:
Additional context