[api] Add Failover field to Backend

Adds a `failover` field to Backend API so we can support Active/Passive
Failove backends within xRoutes similar to envoyproxy#4033

Relates to envoyproxy#3055

Signed-off-by: Arko Dasgupta <arko@tetrate.io>

api/v1alpha1/backend_types.go

@@ -123,6 +123,15 @@ type BackendSpec struct {
 	//
 	// +optional
 	AppProtocols []AppProtocolType `json:"appProtocols,omitempty"`
+
+	// Failover This indicates whether the backend is designated as a failover.
+	// It is highly recommended to configure active or passive health checks to ensure that failover can be detected
+	// when the active backends become unhealthy and to automatically readjust once the primary backends are healthy again.
+	// The overprovisioning factor is set to 1.4, meaning the failover backends will only start receiving traffic when
+	// the health of the active backends falls below 72%.
+	//
+	// +optional
+	Failover *bool `json:"failover,omitempty"`
 }
 
 // BackendConditionType is a type of condition for a backend. This type should be

api/v1alpha1/shared_types.go

@@ -479,6 +479,7 @@ type BackendRef struct {
 	// when the active backends become unhealthy and to automatically readjust once the primary backends are healthy again.
 	// The overprovisioning factor is set to 1.4, meaning the failover backends will only start receiving traffic when
 	// the health of the active backends falls below 72%.
+	//
 	// +optional
 	Failover *bool `json:"failover,omitempty"`
 }

charts/gateway-helm/crds/generated/gateway.envoyproxy.io_backends.yaml

@@ -137,6 +137,14 @@ spec:
                 x-kubernetes-validations:
                 - message: fqdn addresses cannot be mixed with other address types
                   rule: self.all(f, has(f.fqdn)) || !self.exists(f, has(f.fqdn))
+              failover:
+                description: |-
+                  Failover This indicates whether the backend is designated as a failover.
+                  It is highly recommended to configure active or passive health checks to ensure that failover can be detected
+                  when the active backends become unhealthy and to automatically readjust once the primary backends are healthy again.
+                  The overprovisioning factor is set to 1.4, meaning the failover backends will only start receiving traffic when
+                  the health of the active backends falls below 72%.
+                type: boolean
             type: object
           status:
             description: Status defines the current status of Backend.

site/content/en/latest/api/extension_types.md

@@ -380,6 +380,7 @@ _Appears in:_
 | ---   | ---  | ---      | ---         |
 | `endpoints` | _[BackendEndpoint](#backendendpoint) array_ |  true  | Endpoints defines the endpoints to be used when connecting to the backend. |
 | `appProtocols` | _[AppProtocolType](#appprotocoltype) array_ |  false  | AppProtocols defines the application protocols to be supported when connecting to the backend. |
+| `failover` | _boolean_ |  false  | Failover This indicates whether the backend is designated as a failover.<br />It is highly recommended to configure active or passive health checks to ensure that failover can be detected<br />when the active backends become unhealthy and to automatically readjust once the primary backends are healthy again.<br />The overprovisioning factor is set to 1.4, meaning the failover backends will only start receiving traffic when<br />the health of the active backends falls below 72%. |
 
 
 #### BackendStatus

site/content/zh/latest/api/extension_types.md

@@ -380,6 +380,7 @@ _Appears in:_
 | ---   | ---  | ---      | ---         |
 | `endpoints` | _[BackendEndpoint](#backendendpoint) array_ |  true  | Endpoints defines the endpoints to be used when connecting to the backend. |
 | `appProtocols` | _[AppProtocolType](#appprotocoltype) array_ |  false  | AppProtocols defines the application protocols to be supported when connecting to the backend. |
+| `failover` | _boolean_ |  false  | Failover This indicates whether the backend is designated as a failover.<br />It is highly recommended to configure active or passive health checks to ensure that failover can be detected<br />when the active backends become unhealthy and to automatically readjust once the primary backends are healthy again.<br />The overprovisioning factor is set to 1.4, meaning the failover backends will only start receiving traffic when<br />the health of the active backends falls below 72%. |
 
 
 #### BackendStatus