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Clarify ExternalTrafficPolicy/InternalTrafficPolicy definitions

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This commit is contained in:
Dan Winship
2022-03-30 08:43:57 -04:00
parent 0424c7c74d
commit e343ea57a6
7 changed files with 94 additions and 62 deletions
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55
pkg/apis/core/types.go
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@@ -3641,27 +3641,33 @@ const (
ServiceTypeExternalName ServiceType = "ExternalName"
)
// ServiceInternalTrafficPolicyType describes the type of traffic routing for
// internal traffic
// ServiceInternalTrafficPolicyType describes the endpoint-selection policy for
// traffic sent to the ClusterIP.
type ServiceInternalTrafficPolicyType string
const (
// ServiceInternalTrafficPolicyCluster routes traffic to all endpoints
// ServiceInternalTrafficPolicyCluster routes traffic to all endpoints.
ServiceInternalTrafficPolicyCluster ServiceInternalTrafficPolicyType = "Cluster"
// ServiceInternalTrafficPolicyLocal only routes to node-local
// endpoints, otherwise drops the traffic
// ServiceInternalTrafficPolicyLocal routes traffic only to endpoints on the same
// node as the traffic was received on (dropping the traffic if there are no
// local endpoints).
ServiceInternalTrafficPolicyLocal ServiceInternalTrafficPolicyType = "Local"
)
// ServiceExternalTrafficPolicyType string
// ServiceExternalTrafficPolicyType describes the endpoint-selection policy for
// traffic to external service entrypoints (NodePorts, ExternalIPs, and
// LoadBalancer IPs).
type ServiceExternalTrafficPolicyType string
const (
// ServiceExternalTrafficPolicyTypeLocal specifies node-local endpoints behavior.
ServiceExternalTrafficPolicyTypeLocal ServiceExternalTrafficPolicyType = "Local"
// ServiceExternalTrafficPolicyTypeCluster specifies cluster-wide (legacy) behavior.
// ServiceExternalTrafficPolicyTypeCluster routes traffic to all endpoints.
ServiceExternalTrafficPolicyTypeCluster ServiceExternalTrafficPolicyType = "Cluster"
// ServiceExternalTrafficPolicyTypeLocal preserves the source IP of the traffic by
// routing only to endpoints on the same node as the traffic was received on
// (dropping the traffic if there are no local endpoints).
ServiceExternalTrafficPolicyTypeLocal ServiceExternalTrafficPolicyType = "Local"
)
// These are the valid conditions of a service.
@@ -3853,12 +3859,19 @@ type ServiceSpec struct {
// +optional
LoadBalancerSourceRanges []string
// externalTrafficPolicy denotes if this Service desires to route external
// traffic to node-local or cluster-wide endpoints. "Local" preserves the
// client source IP and avoids a second hop for LoadBalancer and Nodeport
// type services, but risks potentially imbalanced traffic spreading.
// "Cluster" obscures the client source IP and may cause a second hop to
// another node, but should have good overall load-spreading.
// externalTrafficPolicy describes how nodes distribute service traffic they
// receive on one of the Service's "externally-facing" addresses (NodePorts,
// ExternalIPs, and LoadBalancer IPs). If set to "Local", the proxy will configure
// the service in a way that assumes that external load balancers will take care
// of balancing the service traffic between nodes, and so each node will deliver
// traffic only to the node-local endpoints of the service, without masquerading
// the client source IP. (Traffic mistakenly sent to a node with no endpoints will
// be dropped.) The default value, "Cluster", uses the standard behavior of
// routing to all endpoints evenly (possibly modified by topology and other
// features). Note that traffic sent to an External IP or LoadBalancer IP from
// within the cluster will always get "Cluster" semantics, but clients sending to
// a NodePort from within the cluster may need to take traffic policy into account
// when picking a node.
// +optional
ExternalTrafficPolicy ServiceExternalTrafficPolicyType
@@ -3905,12 +3918,12 @@ type ServiceSpec struct {
// +optional
LoadBalancerClass *string
// InternalTrafficPolicy specifies if the cluster internal traffic
// should be routed to all endpoints or node-local endpoints only.
// "Cluster" routes internal traffic to a Service to all endpoints.
// "Local" routes traffic to node-local endpoints only, traffic is
// dropped if no node-local endpoints are ready.
// The default value is "Cluster".
// InternalTrafficPolicy describes how nodes distribute service traffic they
// receive on the ClusterIP. If set to "Local", the proxy will assume that pods
// only want to talk to endpoints of the service on the same node as the pod,
// dropping the traffic if there are no local endpoints. The default value,
// "Cluster", uses the standard behavior of routing to all endpoints evenly
// (possibly modified by topology and other features).
// +featureGate=ServiceInternalTrafficPolicy
// +optional
InternalTrafficPolicy *ServiceInternalTrafficPolicyType