Architecture diagram of the k8s scheduler

scheduler.dot

digraph scheduler {
graph [fontname = "helvetica", pad="0.5", nodesep="1", ranksep="2"];

node [fontname = "mono", shape = "box"];
edge [fontname = "helvetica"];

label="\nA partial picture of the k8s scheduler architecture\n"

subgraph cluster_legend {
	style=dashed;
	label="legend"
	structVal [shape="octagon",label="struct value"]
	type [shape="box",label="struct type"]
	interface [shape="box", style="dashed"]
	funcObj [shape="ellipse",style="dashed",label="func value"]
	funcType [shape="ellipse",style="dotted",label="func type"]
	func [shape="ellipse"]
}

// Create subgraphs to group nodes.
subgraph cluster_predicate {
label=""
color="none"
}

subgraph cluster_priority {
label=""
color="none"
}

subgraph cluster_config {
label=""
color="none"
}

subgraph cluster_core {
label=""
color="none"
}

//----------------------------------------
// scheduler.go
subgraph cluster_core {
Scheduler
}
Scheduler -> Config [label="has"]
NewFromConfigurator -> Scheduler [label="produces"]

subgraph cluster_config {
Config
}
Config -> Cache [label="has"]
Config -> eCache [label="has"]
Config -> ScheduleAlgorithm [label="has"]
Config -> GetBinder [label="has"]
Config -> PodConditionUpdater [label="has"]
Config -> PodPreemptor [label="has"]
// TODO: add other func fields

subgraph cluster_config {
Configurator [style="dashed"]
}
Configurator -> Config [label="produces"]

Binder [style="dashed"]
PodConditionUpdater [style="dashed"]
PodPreemptor [style="dashed"]
NewFromConfigurator [shape="ellipse"]
GetBinder [shape="ellipse",style="dashed"]
GetBinder -> Binder [label="produces"]

//----------------------------------------
// factory/factory.go
subgraph cluster_config {
configFactory
}
configFactory -> listers [label="has"]
configFactory -> genericScheduler [label="creates"]  // Keep this?
configFactory -> Configurator [label="implements"]
//configFactory -> Clientset [label="has"]
NewConfigFactory -> configFactory [label="produces"]
NewConfigFactory [shape="ellipse"]
listers [label="Various Listers",style="dashed"]
listers -> Cache [label="updates"]
listers -> eCache [label="updates"]
listers -> SchedulingQueue [label="updates"]

binder
binder -> Binder [label="implements"]
GetBinder->binder [label="has"]
GetBinder->SchedulerExtender [label="has"]

//----------------------------------------
// factory/plugins.go
subgraph cluster_config {
AlgorithmProviderConfig
}
AlgorithmProviderConfig -> ScheduleAlgorithm [label="produces*"]
subgraph cluster_predicate{
PredicateMetadataProducerFactory [shape="ellipse",style="dotted"]
}
PredicateMetadataProducerFactory -> PredicateMetadataProducer [label="produces"]
subgraph cluster_priority {
PriorityMetadataProducerFactory [shape="ellipse",style="dotted"]
}
PriorityMetadataProducerFactory -> PriorityMetadataProducer [label="produces"]

//----------------------------------------
// algorithmprovider/defaults/defaults.go
subgraph cluster_config {
DefaultProvider [shape="octagon"]
ClusterAutoscaleProvider [shape="octagon"]
}
defaults [shape="ellipse",label="defaults.init()"]

//----------------------------------------
// core/generic_scheduler.go
subgraph cluster_core {
genericScheduler
}
genericScheduler -> Cache [label="has"]
genericScheduler -> eCache [label="has"]
genericScheduler -> SchedulingQueue [label="has"]
genericScheduler -> PredicateMetadataProducer [label="has"]
genericScheduler -> PriorityMetadataProducer [label="has"]
genericScheduler -> SchedulerExtender [label="has many"]
genericScheduler -> ScheduleAlgorithm [label="implements"]

//----------------------------------------
// core/extender.go
HTTPExtender -> SchedulerExtender [label="implements"]

//----------------------------------------
// core/scheduling_queue.go
subgraph cluster_core {
SchedulingQueue [style="dashed"]
// hide queue detail
//FIFO -> SchedulingQueue [label="implements"]
//PriorityQueue -> SchedulingQueue [label="implements"]
}

//----------------------------------------
// core/equivalence/equivalence.go
subgraph cluster_core {
eCache [label="equivalence.Cache"]
}

//----------------------------------------
// algorithm/types.go
subgraph cluster_predicate {
PredicateMetadataProducer [shape="ellipse",style="dashed"]
}
PredicateMetadataProducer -> PredicateMetadata [label="produces"]

subgraph cluster_priority {
PriorityMetadataProducer [shape="ellipse",style="dashed"]
}
PriorityMetadataProducer -> PriorityMetadata [label="produces"]

subgraph cluster_predicate {
PredicateMetadata [style="dashed"]
}
subgraph cluster_priority {
PriorityMetadata [style="dashed",label="PriorityMetadata\n(actually interface{})"]
}

//----------------------------------------
// algorithm/scheduler_interface.go (algorithm)
subgraph cluster_core {
ScheduleAlgorithm [style="dashed"]
}
SchedulerExtender [style="dashed"]
SchedulerExtender -> Binder [label="implements"]

//----------------------------------------
// algorithm/predicates/metadata.go
subgraph cluster_predicate {
PredicateMetadataFactory
predicateMetadata
}
PredicateMetadataFactory -> PredicateMetadataProducer [label="implements*"]
PredicateMetadataFactory -> predicateMetadata [label="produces"]
predicateMetadata -> PredicateMetadata [label="implements"]

// algorithm/priorities/metadata.go
subgraph cluster_priority {
PriorityMetadataFactory
priorityMetadata
listers2 [label="Various Listers",style="dashed"]
}
PriorityMetadataFactory -> PriorityMetadataProducer [label="implements*"]
PriorityMetadataFactory -> priorityMetadata [label="produces"]
PriorityMetadataFactory -> listers2 [label="has"]
priorityMetadata -> PriorityMetadata [label="implements"]

//----------------------------------------
// cache/interface.go
subgraph cluster_core {
Cache [label="cache.Cache",style="dashed"]
}


// REGISTERS
DefaultProvider -> AlgorithmProviderConfig [label="RegisterAlgorithmProvider"]
ClusterAutoscaleProvider -> AlgorithmProviderConfig [label="RegisterAlgorithmProvider"]
configFactory->AlgorithmProviderConfig [label="GetAlgorithmProvider"]  // TODO: maybe delete this edge
defaults->PredicateMetadataProducerFactory[label="RegisterPredicateMetadataProducerFactory"]
defaults->PriorityMetadataProducerFactory[label="RegisterPriorityMetadataProducerFactory"]
configFactory->PredicateMetadataProducer [label="GetPredicateMetadataProducer"]
configFactory->PriorityMetadataProducer [label="GetPriorityMetadataProducer"]

}
// TODO: informers & clientset
// TODO: volumebinder?

scheduler.png

scheduler.svg