[feature] add support for sending headers to tracing system

Add support for sending additional HTTP or gRPC headers which
can be used for authentication or other additional information
for the tracing system without having to set up a local instance
of the OpenTelemetry Collector to add these headers.

Example with Dash0:

```yaml
tracing-enabled: false
tracing-transport: "grpc"
tracing-endpoint: "ingress.eu-west-1.aws.dash0.com:4317"
tracing-headers:
  "Authorization": "Bearer DASH0_AUTH_TOKEN"
  "Dash0-Dataset": "gotosocial"
```

Example with Honeycomb:

```yaml
tracing-enabled: false
tracing-transport: "grpc"
tracing-endpoint: "api.honeycomb.io:443"
tracing-headers:
  "x-honeycomb-team": "YOUR_API_KEY"
  "x-honeycomb-dataset": "YOUR_DATASET"
```

docs/advanced/tracing.md

@@ -12,6 +12,9 @@ You'll need the files in [`example/tracing`][ext]. Once you have those you can r
 tracing-enabled: true
 tracing-transport: "grpc"
 tracing-endpoint: "localhost:4317"
+tracing-headers:
+  "Authorization": "Bearer super-secret-token"
+  "Dataset": "gotosocial"
 tracing-insecure-transport: true
 ```
 

docs/configuration/observability.md

@@ -35,6 +35,13 @@ tracing-transport: "grpc"
 # Default: ""
 tracing-endpoint: ""
 
+# Map of strings. Additional headers to send to the trace ingester.
+# Additional HTTP or gRPC headers can be used for authentication or other additional
+# information for the tracing system.
+# Examples: {"Authorization": "Bearer super-secret-token", "Dataset": "gotosocial"}
+# Default: {}
+tracing-headers: {}
+
 # Bool. Disable TLS for the gRPC and HTTP transport protocols.
 # Default: false
 tracing-insecure-transport: false

docs/locales/zh/advanced/tracing.md

@@ -12,6 +12,9 @@ GoToSocial 内置了基于 [OpenTelemetry][otel] 的追踪功能。虽然并没
 tracing-enabled: true
 tracing-transport: "grpc"
 tracing-endpoint: "localhost:4317"
+tracing-headers:
+  "Authorization": "Bearer super-secret-token"
+  "Dataset": "gotosocial"
 tracing-insecure-transport: true
 ```
 

docs/locales/zh/configuration/observability.md

@@ -31,6 +31,11 @@ tracing-transport: "grpc"
 # 默认值: ""
 tracing-endpoint: ""
 
+# TODO
+# 示例: {"Authorization": "Bearer super-secret-token", "Dataset": "gotosocial"}
+# 默认值: {}
+tracing-headers: {}
+
 # 布尔值。禁用gRPC和HTTP传输协议的TLS。
 # 默认值: false
 tracing-insecure-transport: false

example/config.yaml

@@ -928,6 +928,13 @@ tracing-transport: "grpc"
 # Default: ""
 tracing-endpoint: ""
 
+# Map of strings. Additional headers to send to the trace ingester.
+# Additional HTTP or gRPC headers can be used for authentication or other additional
+# information for the tracing system.
+# Examples: {"Authorization": "Bearer super-secret-token", "Dataset": "gotosocial"}
+# Default: {}
+tracing-headers: {}
+
 # Bool. Disable TLS for the gRPC and HTTP transport protocols.
 # Default: false
 tracing-insecure-transport: false

internal/config/config.go

@@ -143,6 +143,7 @@ type Configuration struct {
 	TracingEnabled           bool              `name:"tracing-enabled" usage:"Enable OTLP Tracing"`
 	TracingTransport         string            `name:"tracing-transport" usage:"grpc or http"`
 	TracingEndpoint          string            `name:"tracing-endpoint" usage:"Endpoint of your trace collector. Eg., 'localhost:4317' for gRPC, 'localhost:4318' for http"`
+	TracingHeaders           map[string]string `name:"tracing-headers" usage:"Headers for your trace collector. Eg., 'Authorization: Bearer super-secret-token' for sending an 'Authorization' header"`
 	TracingInsecureTransport bool              `name:"tracing-insecure-transport" usage:"Disable TLS for the gRPC or HTTP transport protocol"`
 
 	MetricsEnabled      bool   `name:"metrics-enabled" usage:"Enable OpenTelemetry based metrics support."`

internal/config/defaults.go

@@ -120,6 +120,7 @@
 	TracingEnabled:           false,
 	TracingTransport:         "grpc",
 	TracingEndpoint:          "",
+	TracingHeaders:           map[string]string{},
 	TracingInsecureTransport: false,
 
 	MetricsEnabled:     false,

internal/config/helpers.gen.go

@@ -2191,6 +2191,22 @@ func (st *ConfigState) SetTracingEndpoint(v string) {
 	st.reloadToViper()
 }
 
+// GetTracingHeaders safely fetches the Configuration value for state's 'TracingHeaders' field
+func (st *ConfigState) GetTracingHeaders() (v map[string]string) {
+	st.mutex.RLock()
+	v = st.config.TracingHeaders
+	st.mutex.RUnlock()
+	return
+}
+
+// SetTracingEndpoint safely sets the Configuration value for state's 'TracingHeaders' field
+func (st *ConfigState) SetTracingHeaders(v map[string]string) {
+	st.mutex.Lock()
+	defer st.mutex.Unlock()
+	st.config.TracingHeaders = v
+	st.reloadToViper()
+}
+
 // TracingEndpointFlag returns the flag name for the 'TracingEndpoint' field
 func TracingEndpointFlag() string { return "tracing-endpoint" }
 

internal/tracing/tracing.go

@@ -60,6 +60,7 @@ func Initialize() error {
 	case "grpc":
 		opts := []otlptracegrpc.Option{
 			otlptracegrpc.WithEndpoint(config.GetTracingEndpoint()),
+			otlptracegrpc.WithHeaders(config.NewState().GetTracingHeaders()),
 		}
 		if insecure {
 			opts = append(opts, otlptracegrpc.WithInsecure())