feat: support Health Check in BackendTrafficPolicy (#2244)

* Add Health Check support to BackendTrafficPolicy

Signed-off-by: lemonlinger <[email protected]>

* use an array of int to represent expected http statuses

Signed-off-by: lemonlinger <[email protected]>

* fix cel validation tests

Signed-off-by: lemonlinger <[email protected]>

* deduplicate http statuses of the slice of ExpectedStatuses

Signed-off-by: lemonlinger <[email protected]>

* fix lint complaints

Signed-off-by: lemonlinger <[email protected]>

* inline health checker into health check config

Signed-off-by: lemonlinger <[email protected]>

* remove grpc health checker

Signed-off-by: lemonlinger <[email protected]>

* fix lint complaints

Signed-off-by: lemonlinger <[email protected]>

---------

Signed-off-by: lemonlinger <[email protected]>

api/v1alpha1/backendtrafficpolicy_types.go

@@ -66,10 +66,16 @@ type BackendTrafficPolicySpec struct {
 	// +optional
 	TCPKeepalive *TCPKeepalive `json:"tcpKeepalive,omitempty"`
 
+	// HealthCheck allows gateway to perform active health checking on backends.
+	//
+	// +optional
+	HealthCheck *HealthCheck `json:"healthCheck,omitempty"`
+
 	// FaultInjection defines the fault injection policy to be applied. This configuration can be used to
 	// inject delays and abort requests to mimic failure scenarios such as service failures and overloads
 	// +optional
 	FaultInjection *FaultInjection `json:"faultInjection,omitempty"`
+
 	// Circuit Breaker settings for the upstream connections and requests.
 	// If not set, circuit breakers will be enabled with the default thresholds
 	//

api/v1alpha1/healthcheck_types.go

@@ -0,0 +1,133 @@
+// Copyright Envoy Gateway Authors
+// SPDX-License-Identifier: Apache-2.0
+// The full text of the Apache license is available in the LICENSE file at
+// the root of the repo.
+
+package v1alpha1
+
+import metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+
+// HealthCheck defines the health check configuration.
+// EG supports various types of health checking including HTTP, TCP.
+// +union
+//
+// +kubebuilder:validation:XValidation:rule="self.type == 'HTTP' ? has(self.http) : !has(self.http)",message="If Health Checker type is HTTP, http field needs to be set."
+// +kubebuilder:validation:XValidation:rule="self.type == 'TCP' ? has(self.tcp) : !has(self.tcp)",message="If Health Checker type is TCP, tcp field needs to be set."
+type HealthCheck struct {
+	// Timeout defines the time to wait for a health check response.
+	//
+	// +kubebuilder:validation:Format=duration
+	// +kubebuilder:default="1s"
+	// +optional
+	Timeout *metav1.Duration `json:"timeout"`
+
+	// Interval defines the time between health checks.
+	//
+	// +kubebuilder:validation:Format=duration
+	// +kubebuilder:default="3s"
+	// +optional
+	Interval *metav1.Duration `json:"interval"`
+
+	// UnhealthyThreshold defines the number of unhealthy health checks required before a backend host is marked unhealthy.
+	//
+	// +kubebuilder:validation:Minimum=1
+	// +kubebuilder:default=3
+	// +optional
+	UnhealthyThreshold *uint32 `json:"unhealthyThreshold"`
+
+	// HealthyThreshold defines the number of healthy health checks required before a backend host is marked healthy.
+	//
+	// +kubebuilder:validation:Minimum=1
+	// +kubebuilder:default=1
+	// +optional
+	HealthyThreshold *uint32 `json:"healthyThreshold"`
+
+	// Type defines the type of health checker.
+	// +kubebuilder:validation:Enum=HTTP;TCP
+	// +unionDiscriminator
+	Type HealthCheckerType `json:"type" yaml:"type"`
+
+	// HTTP defines the configuration of http health checker.
+	// It's required while the health checker type is HTTP.
+	// +optional
+	HTTP *HTTPHealthChecker `json:"http,omitempty" yaml:"http,omitempty"`
+
+	// TCP defines the configuration of tcp health checker.
+	// It's required while the health checker type is TCP.
+	// +optional
+	TCP *TCPHealthChecker `json:"tcp,omitempty" yaml:"tcp,omitempty"`
+}
+
+// HealthCheckerType is the type of health checker.
+// +kubebuilder:validation:Enum=HTTP;TCP
+type HealthCheckerType string
+
+const (
+	// HealthCheckerTypeHTTP defines the HTTP type of health checking.
+	HealthCheckerTypeHTTP HealthCheckerType = "HTTP"
+	// HealthCheckerTypeTCP defines the TCP type of health checking.
+	HealthCheckerTypeTCP HealthCheckerType = "TCP"
+)
+
+// HTTPHealthChecker defines the settings of http health check.
+type HTTPHealthChecker struct {
+	// Path defines the HTTP path that will be requested during health checking.
+	// +kubebuilder:validation:MinLength=1
+	// +kubebuilder:validation:MaxLength=1024
+	Path string `json:"path" yaml:"path"`
+	// Method defines the HTTP method used for health checking.
+	// Defaults to GET
+	// +optional
+	Method *string `json:"method,omitempty" yaml:"method,omitempty"`
+	// ExpectedStatuses defines a list of HTTP response statuses considered healthy.
+	// Defaults to 200 only
+	// +optional
+	ExpectedStatuses []HTTPStatus `json:"expectedStatuses,omitempty" yaml:"expectedStatuses,omitempty"`
+	// ExpectedResponse defines a list of HTTP expected responses to match.
+	// +optional
+	ExpectedResponse *HealthCheckPayload `json:"expectedResponse,omitempty" yaml:"expectedResponse,omitempty"`
+}
+
+// TCPHealthChecker defines the settings of tcp health check.
+type TCPHealthChecker struct {
+	// Send defines the request payload.
+	// +optional
+	Send *HealthCheckPayload `json:"send,omitempty" yaml:"send,omitempty"`
+	// Receive defines the expected response payload.
+	// +optional
+	Receive *HealthCheckPayload `json:"receive,omitempty" yaml:"receive,omitempty"`
+}
+
+// HTTPStatus defines the http status code.
+// +kubebuilder:validation:Minimum=100
+// +kubebuilder:validation:Maximum=600
+// +kubebuilder:validation:ExclusiveMaximum=true
+type HTTPStatus int
+
+// HealthCheckPayloadType is the type of the payload.
+// +kubebuilder:validation:Enum=Text;Binary
+type HealthCheckPayloadType string
+
+const (
+	// HealthCheckPayloadTypeText defines the Text type payload.
+	HealthCheckPayloadTypeText HealthCheckPayloadType = "Text"
+	// HealthCheckPayloadTypeBinary defines the Binary type payload.
+	HealthCheckPayloadTypeBinary HealthCheckPayloadType = "Binary"
+)
+
+// HealthCheckPayload defines the encoding of the payload bytes in the payload.
+// +union
+// +kubebuilder:validation:XValidation:rule="self.type == 'Text' ? has(self.text) : !has(self.text)",message="If payload type is Text, text field needs to be set."
+// +kubebuilder:validation:XValidation:rule="self.type == 'Binary' ? has(self.binary) : !has(self.binary)",message="If payload type is Binary, binary field needs to be set."
+type HealthCheckPayload struct {
+	// Type defines the type of the payload.
+	// +kubebuilder:validation:Enum=Text;Binary
+	// +unionDiscriminator
+	Type HealthCheckPayloadType `json:"type" yaml:"type"`
+	// Text payload in plain text.
+	// +optional
+	Text *string `json:"text,omitempty" yaml:"text,omitempty"`
+	// Binary payload base64 encoded.
+	// +optional
+	Binary []byte `json:"binary,omitempty" yaml:"binary,omitempty"`
+}