Health Check Handler (HTTP health checking)

apiVersion: core/v1
kind: HealthCheckHandler
metadata:
  name: "default"
  namespace: "default"
spec: {}

syntax = "proto3";
package app.v1;

import "buf/validate/validate.proto";
import "core/v1/http.proto";
import "kernel/resource.proto";

option go_package = "github.com/aileron-gateway/aileron-gateway/apis/app/v1";

// HealthCheckHandler resource definition.
// apiVersion="app/v1", kind="HealthCheckHandler".
message HealthCheckHandler {
    string                 APIVersion = 1 [json_name = "apiVersion"];
    string                 Kind       = 2 [json_name = "kind"];
    kernel.Metadata        Metadata   = 3 [json_name = "metadata"];
    HealthCheckHandlerSpec Spec       = 4 [json_name = "spec"];
}

// HealthCheckHandlerSpec is the specifications for the HealthCheckHandler object.
message HealthCheckHandlerSpec {
    // [OPTIONAL]
    // ErrorHandler is the reference to a ErrorHandler object.
    // Referred object must implement ErrorHandler interface.
    // Default error handler is used when not set.
    kernel.Reference ErrorHandler = 1 [json_name = "errorHandler"];

    // [OPTIONAL]
    // Patterns is path patterns that this handler
    // is registered to a server.
    // Default is not set, or empty string ["/"].
    repeated string Patterns = 2 [json_name = "patterns"];

    // [OPTIONA]
    // Methods is the list of HTTP method this handler can handle.
    // Note that it depends on the multiplexer, or HTTP router,
    // that the server uses if this field is used or not.
    // Default multiplexer does not use this field.
    // Default is not set.
    repeated core.v1.HTTPMethod Methods = 3 [json_name = "methods"];

    // [OPTIONAL]
    // Timeout is timeout duration in seconds.
    // Unhealthy status will be returned when health checking excceeded this duration.
    // Default is [30].
    int32 Timeout = 4 [json_name = "timeout", (buf.validate.field).int32 = {gte : 0}];

    // [OPTIONAL]
    // ExternalProbes is the list of references to HealthChecker objects.
    // Referred object must implement HealthChecker interface.
    // No values by default.
    repeated kernel.Reference ExternalProbes = 5 [json_name = "externalProbes"];
}