pkg/appmgmt/interfaces/recoverable.go

/*
 Licensed to the Apache Software Foundation (ASF) under one
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 distributed with this work for additional information
 regarding copyright ownership.  The ASF licenses this file
 to you under the Apache License, Version 2.0 (the
 "License"); you may not use this file except in compliance
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     http://www.apache.org/licenses/LICENSE-2.0

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 See the License for the specific language governing permissions and
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*/

package interfaces

import (
	v1 "k8s.io/api/core/v1"

	"github.com/apache/yunikorn-scheduler-interface/lib/go/si"
)

// recoverable interface defines a certain type of app that can be recovered upon scheduler' restart
// each app manager needs to implement this interface in order to support fault recovery
//
// why we need this?
// the scheduler is stateless, all states are maintained just in memory,
// so each time when scheduler restarts, it needs to recover apps and nodes states from scratch.
// nodes state will be taken care of by the scheduler itself, however for apps state recovery,
// the scheduler will need to call this function to collect existing app info,
// and then properly recover these applications before recovering nodes.
type Recoverable interface {
	// list applications returns all existing applications known to this app manager.
	ListPods() ([]*v1.Pod, error)

	// this is called during recovery
	// for a given pod, return an allocation if found
	GetExistingAllocation(pod *v1.Pod) *si.Allocation
}