[OTLP Exporter] Use env for endpoint, timeout (#451)

Add `with_env` method for `OtlpPipelineBuilder`. This method currently
only configures `endpoint` and `timeout` for OTLP Traces exporter.

Add default constants for those parameters and use them for the default
`ExporterConfig`. Use values defined in specification.

opentelemetry-otlp/src/lib.rs

@@ -123,6 +123,7 @@ use opentelemetry::{global, sdk, trace::TracerProvider};
 #[cfg(all(feature = "grpc-sys", not(feature = "tonic")))]
 use std::collections::HashMap;
 
+use std::str::FromStr;
 use std::time::Duration;
 
 #[cfg(all(feature = "tonic", not(feature = "integration-testing")))]
@@ -197,6 +198,20 @@ pub struct OtlpPipelineBuilder {
     trace_config: Option<sdk::trace::Config>,
 }
 
+/// Target to which the exporter is going to send spans or metrics, defaults to https://localhost:4317.
+const OTEL_EXPORTER_OTLP_ENDPOINT: &str = "OTEL_EXPORTER_OTLP_ENDPOINT";
+/// Default target to which the exporter is going to send spans or metrics.
+const OTEL_EXPORTER_OTLP_ENDPOINT_DEFAULT: &str = "https://localhost:4317";
+/// Max waiting time for the backend to process each spans or metrics batch, defaults to 10 seconds.
+const OTEL_EXPORTER_OTLP_TIMEOUT: &str = "OTEL_EXPORTER_OTLP_TIMEOUT";
+/// Default max waiting time for the backend to process each spans or metrics batch.
+const OTEL_EXPORTER_OTLP_TIMEOUT_DEFAULT: u64 = 10;
+
+/// Target to which the exporter is going to send spans, defaults to https://localhost:4317.
+const OTEL_EXPORTER_OTLP_TRACES_ENDPOINT: &str = "OTEL_EXPORTER_OTLP_TRACES_ENDPOINT";
+/// Max waiting time for the backend to process each spans batch, defaults to 10s.
+const OTEL_EXPORTER_OTLP_TRACES_TIMEOUT: &str = "OTEL_EXPORTER_OTLP_TRACES_TIMEOUT";
+
 impl OtlpPipelineBuilder {
     /// Set the address of the OTLP collector. If not set, the default address is used.
     pub fn with_endpoint<T: Into<String>>(mut self, endpoint: T) -> Self {
@@ -271,6 +286,27 @@ impl OtlpPipelineBuilder {
         self
     }
 
+    /// Set the trace provider configuration from the given environment variables.
+    ///
+    /// If the value in environment variables is illegal, will fall back to use default value.
+    pub fn with_env(mut self) -> Self {
+        let endpoint = match std::env::var(OTEL_EXPORTER_OTLP_TRACES_ENDPOINT) {
+            Ok(val) => val,
+            Err(_) => std::env::var(OTEL_EXPORTER_OTLP_ENDPOINT)
+                .unwrap_or_else(|_| OTEL_EXPORTER_OTLP_ENDPOINT_DEFAULT.to_string()),
+        };
+        self.exporter_config.endpoint = endpoint;
+
+        let timeout = match std::env::var(OTEL_EXPORTER_OTLP_TRACES_TIMEOUT) {
+            Ok(val) => u64::from_str(&val).unwrap_or(OTEL_EXPORTER_OTLP_TIMEOUT_DEFAULT),
+            Err(_) => std::env::var(OTEL_EXPORTER_OTLP_TIMEOUT)
+                .map(|val| u64::from_str(&val).unwrap_or(OTEL_EXPORTER_OTLP_TIMEOUT_DEFAULT))
+                .unwrap_or(OTEL_EXPORTER_OTLP_TIMEOUT_DEFAULT),
+        };
+        self.exporter_config.timeout = Duration::from_secs(timeout);
+        self
+    }
+
     /// Install the OTLP exporter pipeline with the recommended defaults.
     #[cfg(feature = "tonic")]
     pub fn install(mut self) -> Result<(sdk::trace::Tracer, Uninstall), TraceError> {
@@ -348,3 +384,65 @@ pub enum Protocol {
     // HttpJson,
     // HttpProto,
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::{
+        new_pipeline, OTEL_EXPORTER_OTLP_ENDPOINT, OTEL_EXPORTER_OTLP_TIMEOUT,
+        OTEL_EXPORTER_OTLP_TIMEOUT_DEFAULT, OTEL_EXPORTER_OTLP_TRACES_ENDPOINT,
+        OTEL_EXPORTER_OTLP_TRACES_TIMEOUT,
+    };
+
+    #[test]
+    fn test_pipeline_builder_from_otlp_env() {
+        std::env::set_var(OTEL_EXPORTER_OTLP_ENDPOINT, "https://otlp_endpoint:4317");
+        std::env::set_var(OTEL_EXPORTER_OTLP_TIMEOUT, "bad_timeout");
+
+        let mut pipeline_builder = new_pipeline().with_env();
+        assert_eq!(
+            pipeline_builder.exporter_config.timeout,
+            std::time::Duration::from_secs(OTEL_EXPORTER_OTLP_TIMEOUT_DEFAULT)
+        );
+
+        std::env::set_var(OTEL_EXPORTER_OTLP_TIMEOUT, "60");
+
+        pipeline_builder = new_pipeline().with_env();
+        assert_eq!(
+            pipeline_builder.exporter_config.timeout,
+            std::time::Duration::from_secs(60)
+        );
+
+        std::env::remove_var(OTEL_EXPORTER_OTLP_ENDPOINT);
+        std::env::remove_var(OTEL_EXPORTER_OTLP_TIMEOUT);
+        assert!(std::env::var(OTEL_EXPORTER_OTLP_ENDPOINT).is_err());
+        assert!(std::env::var(OTEL_EXPORTER_OTLP_TIMEOUT).is_err());
+    }
+
+    #[test]
+    fn test_pipeline_builder_from_otlp_traces_env() {
+        std::env::set_var(
+            OTEL_EXPORTER_OTLP_TRACES_ENDPOINT,
+            "https://otlp_traces_endpoint:4317",
+        );
+        std::env::set_var(OTEL_EXPORTER_OTLP_TRACES_TIMEOUT, "bad_timeout");
+
+        let mut pipeline_builder = new_pipeline().with_env();
+        assert_eq!(
+            pipeline_builder.exporter_config.timeout,
+            std::time::Duration::from_secs(OTEL_EXPORTER_OTLP_TIMEOUT_DEFAULT)
+        );
+
+        std::env::set_var(OTEL_EXPORTER_OTLP_TRACES_TIMEOUT, "60");
+
+        pipeline_builder = new_pipeline().with_env();
+        assert_eq!(
+            pipeline_builder.exporter_config.timeout,
+            std::time::Duration::from_secs(60)
+        );
+
+        std::env::remove_var(OTEL_EXPORTER_OTLP_TRACES_ENDPOINT);
+        std::env::remove_var(OTEL_EXPORTER_OTLP_TRACES_TIMEOUT);
+        assert!(std::env::var(OTEL_EXPORTER_OTLP_TRACES_ENDPOINT).is_err());
+        assert!(std::env::var(OTEL_EXPORTER_OTLP_TRACES_TIMEOUT).is_err());
+    }
+}

opentelemetry-otlp/src/span.rs

@@ -42,7 +42,7 @@ use std::fmt::Debug;
 #[cfg(all(feature = "grpc-sys", not(feature = "tonic")))]
 use std::sync::Arc;
 
-use crate::Protocol;
+use crate::{Protocol, OTEL_EXPORTER_OTLP_ENDPOINT_DEFAULT, OTEL_EXPORTER_OTLP_TIMEOUT_DEFAULT};
 use opentelemetry::sdk::export::trace::{ExportResult, SpanData, SpanExporter};
 use std::time::Duration;
 
@@ -138,18 +138,16 @@ impl Into<grpcio::CompressionAlgorithms> for Compression {
     }
 }
 
-const DEFAULT_OTLP_PORT: u16 = 4317;
-
 impl Default for ExporterConfig {
     #[cfg(feature = "tonic")]
     fn default() -> Self {
         ExporterConfig {
-            endpoint: format!("http://localhost:{}", DEFAULT_OTLP_PORT),
+            endpoint: OTEL_EXPORTER_OTLP_ENDPOINT_DEFAULT.to_string(),
             protocol: Protocol::Grpc,
             #[cfg(all(feature = "tonic", feature = "tls"))]
             tls_config: None,
             metadata: None,
-            timeout: Duration::from_secs(60),
+            timeout: Duration::from_secs(OTEL_EXPORTER_OTLP_TIMEOUT_DEFAULT),
             #[cfg(not(feature = "async"))]
             runtime: None,
         }
@@ -158,13 +156,13 @@ impl Default for ExporterConfig {
     #[cfg(all(feature = "grpc-sys", not(feature = "tonic")))]
     fn default() -> Self {
         ExporterConfig {
-            endpoint: format!("localhost:{}", DEFAULT_OTLP_PORT),
+            endpoint: OTEL_EXPORTER_OTLP_ENDPOINT_DEFAULT.to_string(),
             protocol: Protocol::Grpc,
             credentials: None,
             headers: None,
             compression: None,
             use_tls: None,
-            timeout: Duration::from_secs(60),
+            timeout: Duration::from_secs(OTEL_EXPORTER_OTLP_TIMEOUT_DEFAULT),
             completion_queue_count: 2,
         }
     }