Merge pull request #2463 from calebschoepp/grpc-otel

feat(telemetry): Make telemetry support http/protobuf protocol in addition to grpc protocol

crates/telemetry/Cargo.toml

@@ -10,7 +10,7 @@ http0 = { version = "0.2.9", package = "http" }
 http1 = { version = "1.0.0", package = "http" }
 opentelemetry = { version = "0.22.0", features = [ "metrics", "trace"] }
 opentelemetry_sdk = { version = "0.22.1", features = ["rt-tokio"] }
-opentelemetry-otlp = { version = "0.15.0", default_features=false, features = ["http-proto", "trace", "http", "reqwest-client", "metrics"] }
+opentelemetry-otlp = { version = "0.15.0", default_features=false, features = ["http-proto", "trace", "http", "reqwest-client", "metrics", "grpc-tonic"] }
 opentelemetry-semantic-conventions = "0.14.0"
 tracing = { version = "0.1.37", features = ["log"] }
 tracing-appender = "0.2.2"

crates/telemetry/src/env.rs

@@ -0,0 +1,48 @@
+/// Returns a boolean indicating if the OTEL layer should be enabled.
+///
+/// It is considered enabled if any of the following environment variables are set and not empty:
+/// - `OTEL_EXPORTER_OTLP_ENDPOINT`
+/// - `OTEL_EXPORTER_OTLP_TRACES_ENDPOINT`
+/// - `OTEL_EXPORTER_OTLP_METRICS_ENDPOINT`
+///
+/// Note that this is overridden if OTEL_SDK_DISABLED is set and not empty.
+pub(crate) fn otel_enabled() -> bool {
+    const ENABLING_VARS: &[&str] = &[
+        "OTEL_EXPORTER_OTLP_ENDPOINT",
+        "OTEL_EXPORTER_OTLP_TRACES_ENDPOINT",
+        "OTEL_EXPORTER_OTLP_METRICS_ENDPOINT",
+    ];
+    ENABLING_VARS
+        .iter()
+        .any(|key| std::env::var_os(key).is_some_and(|val| !val.is_empty()))
+}
+
+/// Returns a boolean indicating if the OTEL SDK should be disabled for all signals.
+///
+/// It is considered disabled if the environment variable `OTEL_SDK_DISABLED` is set and not empty.
+pub(crate) fn otel_sdk_disabled() -> bool {
+    std::env::var_os("OTEL_SDK_DISABLED").is_some_and(|val| !val.is_empty())
+}
+
+/// The protocol to use for OTLP exporter.
+pub(crate) enum OtlpProtocol {
+    Grpc,
+    HttpProtobuf,
+    HttpJson,
+}
+
+impl OtlpProtocol {
+    /// Returns the protocol to be used for exporting traces as defined by the environment.
+    pub(crate) fn traces_protocol_from_env() -> Self {
+        let trace_protocol = std::env::var("OTEL_EXPORTER_OTLP_TRACES_PROTOCOL");
+        let general_protocol = std::env::var("OTEL_EXPORTER_OTLP_PROTOCOL");
+        let protocol = trace_protocol.unwrap_or(general_protocol.unwrap_or_default());
+
+        match protocol.as_str() {
+            "grpc" => Self::Grpc,
+            "http/protobuf" => Self::HttpProtobuf,
+            "http/json" => Self::HttpJson,
+            _ => Self::HttpProtobuf,
+        }
+    }
+}

crates/telemetry/src/lib.rs

@@ -1,9 +1,12 @@
 use std::io::IsTerminal;
 
+use env::otel_enabled;
+use env::otel_sdk_disabled;
 use opentelemetry_sdk::propagation::TraceContextPropagator;
 use tracing_subscriber::{fmt, prelude::*, registry, EnvFilter, Layer};
 
 pub mod detector;
+mod env;
 mod propagation;
 mod traces;
 
@@ -48,32 +51,6 @@ pub fn init(spin_version: String) -> anyhow::Result<ShutdownGuard> {
     Ok(ShutdownGuard)
 }
 
-/// Returns a boolean indicating if the OTEL layer should be enabled.
-///
-/// It is considered enabled if any of the following environment variables are set and not empty:
-/// - `OTEL_EXPORTER_OTLP_ENDPOINT`
-/// - `OTEL_EXPORTER_OTLP_TRACES_ENDPOINT`
-/// - `OTEL_EXPORTER_OTLP_METRICS_ENDPOINT`
-///
-/// Note that this is overridden if OTEL_SDK_DISABLED is set and not empty.
-fn otel_enabled() -> bool {
-    const ENABLING_VARS: &[&str] = &[
-        "OTEL_EXPORTER_OTLP_ENDPOINT",
-        "OTEL_EXPORTER_OTLP_TRACES_ENDPOINT",
-        "OTEL_EXPORTER_OTLP_METRICS_ENDPOINT",
-    ];
-    ENABLING_VARS
-        .iter()
-        .any(|key| std::env::var_os(key).is_some_and(|val| !val.is_empty()))
-}
-
-/// Returns a boolean indicating if the OTEL SDK should be disabled for all signals.
-///
-/// It is considered disabled if the environment variable `OTEL_SDK_DISABLED` is set and not empty.
-fn otel_sdk_disabled() -> bool {
-    std::env::var_os("OTEL_SDK_DISABLED").is_some_and(|val| !val.is_empty())
-}
-
 fn otel_error_handler(err: opentelemetry::global::Error) {
     static FIRST_OTEL_ERROR: std::sync::Once = std::sync::Once::new();
     FIRST_OTEL_ERROR.call_once(|| {

crates/telemetry/src/traces.rs

@@ -1,6 +1,7 @@
 use std::time::Duration;
 
-use opentelemetry_otlp::WithExportConfig;
+use anyhow::bail;
+use opentelemetry_otlp::{SpanExporterBuilder, WithExportConfig};
 use opentelemetry_otlp::{OTEL_EXPORTER_OTLP_ENDPOINT, OTEL_EXPORTER_OTLP_TRACES_ENDPOINT};
 use opentelemetry_sdk::{
     resource::{EnvResourceDetector, TelemetryResourceDetector},
@@ -11,6 +12,7 @@ use tracing_opentelemetry::OpenTelemetryLayer;
 use tracing_subscriber::{EnvFilter, Layer, Registry};
 
 use crate::detector::SpinResourceDetector;
+use crate::env::OtlpProtocol;
 
 /// Constructs a layer for the tracing subscriber that sends spans to an OTEL collector.
 ///
@@ -39,9 +41,17 @@ pub(crate) fn otel_tracing_layer(
     // currently default to using the HTTP exporter but in the future we could select off of the
     // combination of OTEL_EXPORTER_OTLP_PROTOCOL and OTEL_EXPORTER_OTLP_TRACES_PROTOCOL to
     // determine whether we should use http/protobuf or grpc.
-    let mut exporter = opentelemetry_otlp::new_exporter().http();
+    let mut exporter: SpanExporterBuilder = match OtlpProtocol::traces_protocol_from_env() {
+        OtlpProtocol::Grpc => opentelemetry_otlp::new_exporter().tonic().into(),
+        OtlpProtocol::HttpProtobuf => opentelemetry_otlp::new_exporter().http().into(),
+        OtlpProtocol::HttpJson => bail!("http/json OTLP protocol is not supported"),
+    };
     if let Some(endpoint) = fix_endpoint_bug() {
-        exporter = exporter.with_endpoint(endpoint);
+        match exporter {
+            SpanExporterBuilder::Tonic(inner) => exporter = inner.with_endpoint(endpoint).into(),
+            SpanExporterBuilder::Http(inner) => exporter = inner.with_endpoint(endpoint).into(),
+            _ => {}
+        }
     }
 
     let tracer = opentelemetry_otlp::new_pipeline()