Fix defaults, add tests

component/otelcol/exporter/loadbalancing/loadbalancing.go

@@ -213,12 +213,12 @@ type KubernetesResolver struct {
 
 var _ river.Defaulter = &KubernetesResolver{}
 
-// DefaultDNSResolver holds default values for K8sSvcResolver.
-var DefaultK8sSvcResolver = KubernetesResolver{}
-
 // SetToDefault implements river.Defaulter.
 func (args *KubernetesResolver) SetToDefault() {
-	*args = DefaultK8sSvcResolver
+	if args == nil {
+		args = &KubernetesResolver{}
+	}
+	args.Ports = []int32{4317}
 }
 
 func (k8sSvcResolver *KubernetesResolver) Convert() loadbalancingexporter.K8sSvcResolver {

component/otelcol/exporter/loadbalancing/loadbalancing_test.go

@@ -222,6 +222,7 @@ func TestConfigConversion(t *testing.T) {
 					Static: nil,
 					K8sSvc: &loadbalancingexporter.K8sSvcResolver{
 						Service: "lb-svc.lb-ns",
+						Ports:   []int32{4317},
 					},
 				},
 				RoutingKey: "traceID",

docs/sources/flow/reference/components/otelcol.exporter.loadbalancing.md

@@ -149,7 +149,7 @@ The following arguments are supported:
 Name | Type | Description | Default | Required
 ---- | ---- | ----------- | ------- | --------
 `service` | `string`       | Kubernetes service to resolve. |  | yes
-`ports`   | `list(number)` | Ports to use with the IP addresses resolved from `service`. | `["4317"]` | no
+`ports`   | `list(number)` | Ports to use with the IP addresses resolved from `service`. | `[4317]` | no
 
 If no namespace is specified inside `service`, an attempt will be made to infer the namespace for this Agent. 
 If this fails, the `default` namespace will be used.

pkg/traces/config.go

@@ -589,7 +589,7 @@ func resolver(config map[string]interface{}) (map[string]interface{}, error) {
 		case dnsTagName, staticTagName:
 			resolverCfg[typ] = cfg
 		case kubernetesTagName:
-			resolverCfg[typ] = "k8s"
+			resolverCfg["k8s"] = cfg
 		default:
 			return nil, fmt.Errorf("unsupported resolver config type: %s", typ)
 		}

pkg/traces/config_test.go

@@ -754,7 +754,7 @@ service:
 `,
 		},
 		{
-			name: "tail sampling config with load balancing",
+			name: "tail sampling config with DNS load balancing",
 			cfg: `
 receivers:
   jaeger:
@@ -829,6 +829,94 @@ processors:
             - value1
             - value2
 extensions: {}
+service:
+  pipelines:
+    traces/0:
+      exporters: ["loadbalancing"]
+      processors: []
+      receivers: ["jaeger", "push_receiver"]
+    traces/1:
+      exporters: ["otlp/0"]
+      processors: ["tail_sampling"]
+      receivers: ["otlp/lb"]
+`,
+		},
+		{
+			name: "tail sampling config with Kubernetes load balancing",
+			cfg: `
+receivers:
+  jaeger:
+    protocols:
+      grpc:
+remote_write:
+  - endpoint: example.com:12345
+tail_sampling:
+  policies:
+    - type: always_sample
+    - type: string_attribute
+      string_attribute:
+        key: key
+        values:
+          - value1
+          - value2
+load_balancing:
+  receiver_port: 8181
+  routing_key: service
+  exporter:
+    insecure: true
+  resolver:
+    kubernetes:
+      service: lb-svc.lb-ns
+      ports:
+      - 55690
+      - 55691
+`,
+			expectedConfig: `
+receivers:
+  jaeger:
+    protocols:
+      grpc:
+  push_receiver: {}
+  otlp/lb:
+    protocols:
+      grpc:
+        endpoint: "0.0.0.0:8181"
+exporters:
+  otlp/0:
+    endpoint: example.com:12345
+    compression: gzip
+    retry_on_failure:
+      max_elapsed_time: 60s
+  loadbalancing:
+    routing_key: service
+    protocol:
+      otlp:
+        tls:
+          insecure: true
+        endpoint: noop
+        retry_on_failure:
+          max_elapsed_time: 60s
+        compression: none
+    resolver:
+      k8s:
+        service: lb-svc.lb-ns
+        ports:
+        - 55690
+        - 55691
+processors:
+  tail_sampling:
+    decision_wait: 5s
+    policies:
+      - name: always_sample/0
+        type: always_sample
+      - name: string_attribute/1
+        type: string_attribute
+        string_attribute:
+          key: key
+          values:
+            - value1
+            - value2
+extensions: {}
 service:
   pipelines:
     traces/0: