> ## Documentation Index > Fetch the complete documentation index at: https://mintlify.com/open-telemetry/opentelemetry-rust/llms.txt > Use this file to discover all available pages before exploring further. # Runtime configuration > Configure OpenTelemetry using environment variables and feature flags ## Overview OpenTelemetry Rust can be configured through: * Environment variables (runtime configuration) * Cargo feature flags (compile-time configuration) * Programmatic configuration (in code) ## Environment variables ### General configuration | Variable | Description | Default | | -------------------------- | ----------------------------------------------- | ----------------- | | `OTEL_SDK_DISABLED` | Disable the SDK | `false` | | `OTEL_RESOURCE_ATTRIBUTES` | Resource attributes as key-value pairs | | | `OTEL_SERVICE_NAME` | Service name | `unknown_service` | | `OTEL_LOG_LEVEL` | SDK log level (error, warn, info, debug, trace) | `info` | ### OTLP exporter configuration | Variable | Description | Default | | -------------------------------- | ----------------------------------------- | ----------------------- | | `OTEL_EXPORTER_OTLP_ENDPOINT` | OTLP endpoint URL | `http://localhost:4317` | | `OTEL_EXPORTER_OTLP_PROTOCOL` | Protocol (grpc, http/protobuf, http/json) | `grpc` | | `OTEL_EXPORTER_OTLP_TIMEOUT` | Export timeout in milliseconds | `10000` | | `OTEL_EXPORTER_OTLP_HEADERS` | Headers as key-value pairs | | | `OTEL_EXPORTER_OTLP_COMPRESSION` | Compression (gzip, none) | `none` | ### Signal-specific endpoints | Variable | Description | | ------------------------------------- | ---------------- | | `OTEL_EXPORTER_OTLP_TRACES_ENDPOINT` | Traces endpoint | | `OTEL_EXPORTER_OTLP_METRICS_ENDPOINT` | Metrics endpoint | | `OTEL_EXPORTER_OTLP_LOGS_ENDPOINT` | Logs endpoint | | `OTEL_EXPORTER_OTLP_TRACES_HEADERS` | Traces headers | | `OTEL_EXPORTER_OTLP_METRICS_HEADERS` | Metrics headers | | `OTEL_EXPORTER_OTLP_LOGS_HEADERS` | Logs headers | ### Batch processor configuration **Spans:** | Variable | Description | Default | | -------------------------------- | -------------------- | ------- | | `OTEL_BSP_MAX_QUEUE_SIZE` | Max queue size | `2048` | | `OTEL_BSP_MAX_EXPORT_BATCH_SIZE` | Max batch size | `512` | | `OTEL_BSP_SCHEDULE_DELAY` | Export interval (ms) | `5000` | | `OTEL_BSP_EXPORT_TIMEOUT` | Export timeout (ms) | `30000` | **Logs:** | Variable | Description | Default | | --------------------------------- | -------------------- | ------- | | `OTEL_BLRP_MAX_QUEUE_SIZE` | Max queue size | `2048` | | `OTEL_BLRP_MAX_EXPORT_BATCH_SIZE` | Max batch size | `512` | | `OTEL_BLRP_SCHEDULE_DELAY` | Export interval (ms) | `1000` | | `OTEL_BLRP_EXPORT_TIMEOUT` | Export timeout (ms) | `30000` | ### Trace configuration | Variable | Description | Default | | ----------------------------------- | -------------------------- | ----------------------- | | `OTEL_TRACES_SAMPLER` | Sampler type | `parentbased_always_on` | | `OTEL_TRACES_SAMPLER_ARG` | Sampler argument | | | `OTEL_SPAN_ATTRIBUTE_COUNT_LIMIT` | Max attributes per span | `128` | | `OTEL_SPAN_EVENT_COUNT_LIMIT` | Max events per span | `128` | | `OTEL_SPAN_LINK_COUNT_LIMIT` | Max links per span | `128` | | `OTEL_ATTRIBUTE_VALUE_LENGTH_LIMIT` | Max attribute value length | unlimited | ### Sampler types * `always_on` - Sample all spans * `always_off` - Sample no spans * `traceidratio` - Sample based on trace ID (requires `OTEL_TRACES_SAMPLER_ARG` = ratio) * `parentbased_always_on` - Use parent decision, otherwise always sample * `parentbased_always_off` - Use parent decision, otherwise never sample * `parentbased_traceidratio` - Use parent decision, otherwise ratio-based ### Propagator configuration | Variable | Description | Default | | ------------------ | ----------------------------------- | ---------------------- | | `OTEL_PROPAGATORS` | Comma-separated list of propagators | `tracecontext,baggage` | Supported propagators: * `tracecontext` - W3C Trace Context * `baggage` - W3C Baggage * `b3` - B3 single header * `b3multi` - B3 multi header * `jaeger` - Jaeger propagation * `xray` - AWS X-Ray * `ottrace` - OpenTracing ## Feature flags ### opentelemetry crate ```toml theme={null} [dependencies] opentelemetry = { version = "0.31", features = [ "trace", # Tracing API "metrics", # Metrics API "logs", # Logs API "internal-logs", # Internal SDK logging ]} ``` ### opentelemetry-sdk crate ```toml theme={null} [dependencies] opentelemetry_sdk = { version = "0.31", features = [ "trace", # Tracing SDK "metrics", # Metrics SDK "logs", # Logs SDK "rt-tokio", # Tokio runtime for batch processors "rt-tokio-current-thread", # Tokio current-thread runtime ]} ``` **Experimental features:** ```toml theme={null} [dependencies] opentelemetry_sdk = { version = "0.31", features = [ "jaeger_remote_sampler", # Jaeger remote sampling "experimental_metrics_periodicreader_with_async_runtime", "experimental_logs_batch_log_processor_with_async_runtime", "experimental_trace_batch_span_processor_with_async_runtime", ]} ``` ### opentelemetry-otlp crate ```toml theme={null} [dependencies] opentelemetry-otlp = { version = "0.31", features = [ "grpc-tonic", # gRPC with tonic "http-proto", # HTTP with protobuf "http-json", # HTTP with JSON "reqwest-blocking", # Blocking reqwest client "reqwest-rustls", # Reqwest with rustls "compression-gzip", # gzip compression "compression-zstd", # zstd compression ]} ``` ## Complete configuration example ### Environment file (.env) ```bash theme={null} # Service identification OTEL_SERVICE_NAME=my-rust-service OTEL_RESOURCE_ATTRIBUTES=service.version=1.0.0,deployment.environment=production # OTLP exporter OTEL_EXPORTER_OTLP_ENDPOINT=https://otel-collector.example.com:4317 OTEL_EXPORTER_OTLP_PROTOCOL=grpc OTEL_EXPORTER_OTLP_HEADERS=api-key=secret123 OTEL_EXPORTER_OTLP_COMPRESSION=gzip OTEL_EXPORTER_OTLP_TIMEOUT=30000 # Batch processing OTEL_BSP_MAX_QUEUE_SIZE=4096 OTEL_BSP_MAX_EXPORT_BATCH_SIZE=1024 OTEL_BSP_SCHEDULE_DELAY=10000 # Sampling OTEL_TRACES_SAMPLER=parentbased_traceidratio OTEL_TRACES_SAMPLER_ARG=0.1 # Propagation OTEL_PROPAGATORS=tracecontext,baggage # Limits OTEL_SPAN_ATTRIBUTE_COUNT_LIMIT=256 OTEL_SPAN_EVENT_COUNT_LIMIT=256 ``` ### Cargo.toml ```toml theme={null} [dependencies] opentelemetry = { version = "0.31", features = ["trace", "metrics", "logs"] } opentelemetry_sdk = { version = "0.31", features = ["trace", "metrics", "logs", "rt-tokio"] } opentelemetry-otlp = { version = "0.31", features = [ "grpc-tonic", "compression-gzip", "reqwest-rustls", ]} ``` ### Application code ```rust theme={null} use opentelemetry::global; use opentelemetry_sdk::{ trace::{TracerProvider, BatchSpanProcessor}, Resource, runtime::Tokio, }; use opentelemetry_otlp::SpanExporter; #[tokio::main] async fn main() -> Result<(), Box> { // Resource detection uses OTEL_SERVICE_NAME and OTEL_RESOURCE_ATTRIBUTES let resource = Resource::builder().build(); // Exporter uses OTEL_EXPORTER_OTLP_* variables let exporter = SpanExporter::builder() .with_tonic() // Uses OTEL_EXPORTER_OTLP_ENDPOINT .build()?; // Batch processor uses OTEL_BSP_* variables let processor = BatchSpanProcessor::builder(exporter, Tokio).build(); let provider = TracerProvider::builder() .with_resource(resource) .with_span_processor(processor) .build(); global::set_tracer_provider(provider); // Application code... global::shutdown_tracer_provider(); Ok(()) } ``` ## Override precedence Configuration is resolved in this order (highest to lowest priority): 1. **Programmatic configuration** - Values set in code 2. **Environment variables** - Runtime configuration 3. **Default values** - Built-in defaults ```rust theme={null} // Programmatic configuration takes precedence let exporter = SpanExporter::builder() .with_tonic() .with_endpoint("http://custom-endpoint:4317") // Overrides OTEL_EXPORTER_OTLP_ENDPOINT .build()?; ``` ## Best practices **Use environment variables for deployment** - Different environments (dev, staging, prod) can have different configurations without code changes. **Validate configuration** - Check that environment variables are set correctly before running in production. **Secure sensitive values** - Don't commit API keys or tokens to version control. Use secret management systems. **Feature flags reduce binary size** - Only enable the features you need to minimize dependencies and compile time. ## Configuration by environment ### Development ```bash theme={null} OTEL_SERVICE_NAME=my-service-dev OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4317 OTEL_TRACES_SAMPLER=always_on OTEL_BSP_SCHEDULE_DELAY=1000 # Fast export for debugging ``` ### Staging ```bash theme={null} OTEL_SERVICE_NAME=my-service-staging OTEL_EXPORTER_OTLP_ENDPOINT=https://staging-collector.example.com:4317 OTEL_TRACES_SAMPLER=parentbased_traceidratio OTEL_TRACES_SAMPLER_ARG=0.5 # 50% sampling OTEL_RESOURCE_ATTRIBUTES=deployment.environment=staging ``` ### Production ```bash theme={null} OTEL_SERVICE_NAME=my-service OTEL_EXPORTER_OTLP_ENDPOINT=https://collector.example.com:4317 OTEL_EXPORTER_OTLP_HEADERS=api-key=${SECRET_API_KEY} OTEL_TRACES_SAMPLER=parentbased_traceidratio OTEL_TRACES_SAMPLER_ARG=0.1 # 10% sampling OTEL_RESOURCE_ATTRIBUTES=deployment.environment=production,service.version=${APP_VERSION} OTEL_BSP_MAX_QUEUE_SIZE=8192 # Higher throughput ``` ## Related Configure resource attributes Tune batch processor settings