refactor: remove pointer, add envconfig and test

Signed-off-by: Mike Beaumont <mjboamail@gmail.com>

docs/generated/kuma-cp.md

@@ -700,4 +700,8 @@ proxy:
     # Sets the envoy runtime value to limit maximum number of incoming
     # connections to a builtin gateway data plane proxy
     globalDownstreamMaxConnections: 50000 # ENV: KUMA_PROXY_GATEWAY_GLOBAL_DOWNSTREAM_MAX_CONNECTIONS
+
+tracing:
+  openTelemetry:
+    endpoint: "" # e.g. otel-collector:4317
 ```

pkg/api-server/server.go

@@ -122,9 +122,7 @@ func NewApiServer(
 	}
 	container.Filter(cors.Filter)
 
-	if cfg.Tracing != nil {
-		container.Filter(otelrestful.OTelFilter("api-server"))
-	}
+	container.Filter(otelrestful.OTelFilter("api-server"))
 
 	// We create a WebService and set up resources endpoints and index endpoint instead of creating WebService
 	// for every resource like /meshes/{mesh}/traffic-permissions, /meshes/{mesh}/traffic-log etc.

pkg/config/app/kuma-cp/config.go

@@ -152,7 +152,7 @@ type Config struct {
 	// Intercommunication CP configuration
 	InterCp intercp.InterCpConfig `json:"interCp"`
 	// Tracing
-	Tracing *tracing.Config `json:"tracing"`
+	Tracing tracing.Config `json:"tracing"`
 }
 
 func (c *Config) Sanitize() {
@@ -290,6 +290,9 @@ func (c *Config) Validate() error {
 	if err := c.InterCp.Validate(); err != nil {
 		return errors.Wrap(err, "InterCp validation failed")
 	}
+	if err := c.Tracing.Validate(); err != nil {
+		return errors.Wrap(err, "Tracing validation failed")
+	}
 	return nil
 }
 

pkg/config/app/kuma-cp/kuma-cp.defaults.yaml

@@ -697,3 +697,7 @@ proxy:
     # Sets the envoy runtime value to limit maximum number of incoming
     # connections to a builtin gateway data plane proxy
     globalDownstreamMaxConnections: 50000 # ENV: KUMA_PROXY_GATEWAY_GLOBAL_DOWNSTREAM_MAX_CONNECTIONS
+
+tracing:
+  openTelemetry:
+    endpoint: "" # e.g. otel-collector:4317

pkg/config/loader_test.go

@@ -888,6 +888,7 @@ proxy:
 				"KUMA_EXPERIMENTAL_USE_TAG_FIRST_VIRTUAL_OUTBOUND_MODEL":                                   "false",
 				"KUMA_EXPERIMENTAL_INGRESS_TAG_FILTERS":                                                    "kuma.io/service",
 				"KUMA_PROXY_GATEWAY_GLOBAL_DOWNSTREAM_MAX_CONNECTIONS":                                     "1",
+				"KUMA_TRACING_OPENTELEMETRY_ENDPOINT":                                                      "otel-collector:4317",
 			},
 			yamlFileConfig: "",
 		}),

pkg/config/tracing/config.go

@@ -1,11 +1,23 @@
 package tracing
 
 type Config struct {
-	OpenTelemetry OpenTelemetry `json:"openTelemetry"`
+	OpenTelemetry OpenTelemetry `json:"openTelemetry,omitempty"`
+}
+
+func (c Config) Validate() error {
+	if err := c.OpenTelemetry.Validate(); err != nil {
+		return err
+	}
+
+	return nil
 }
 
 type OpenTelemetry struct {
 	// Address of OpenTelemetry collector.
 	// E.g. otel-collector:4317
-	Endpoint string `json:"endpoint"`
+	Endpoint string `json:"endpoint,omitempty" envconfig:"kuma_tracing_opentelemetry_endpoint"`
+}
+
+func (c OpenTelemetry) Validate() error {
+	return nil
 }

pkg/plugins/runtime/opentelemetry/plugin.go

@@ -55,13 +55,13 @@ func (t *tracer) NeedLeaderElection() bool {
 }
 
 func (p *plugin) Customize(rt core_runtime.Runtime) error {
-	tracing := rt.Config().Tracing
-	if tracing == nil {
+	otel := rt.Config().Tracing.OpenTelemetry
+	if otel.Endpoint == "" {
 		return nil
 	}
 
 	t := tracer{
-		config: tracing.OpenTelemetry,
+		config: otel,
 	}
 	if err := rt.Add(component.NewResilientComponent(core.Log.WithName("otel-tracer"), &t)); err != nil {
 		return err