feat(opentelemetry-resource-detectors): add LambdaResourceDetector …

…to detect resource attributes from an AWS Lambda environment.

This commits introduces the `LambdaResourceDetector`, that can be used to detect resource attributes from an AWS Lambda environment.
A new feature flag has been introduced `aws-lambda` to hide this code when it is not needed.

Signed-off-by: thomas.gouveia <[email protected]>
Signed-off-by: thomasgouveia <[email protected]>

opentelemetry-resource-detectors/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## vNext
 
+### Added
+
+- `LambdaResourceDetector` has been added to the crate to detect AWS Lambda attributes. To enable it in your code, use the feature `aws-lambda`.
+
 ## v0.3.0
 
 ### Changed

opentelemetry-resource-detectors/Cargo.toml

@@ -16,3 +16,9 @@ rust-version = "1.65"
 opentelemetry = { workspace = true }
 opentelemetry_sdk = { workspace = true }
 opentelemetry-semantic-conventions = { workspace = true }
+
+[dev-dependencies]
+sealed_test = "1.1.0"
+
+[features]
+aws-lambda = []

opentelemetry-resource-detectors/src/aws.rs

@@ -0,0 +1,5 @@
+#[cfg(feature = "aws-lambda")]
+mod lambda;
+#[cfg(feature = "aws-lambda")]
+pub use lambda::LambdaResourceDetector;
+

opentelemetry-resource-detectors/src/aws/lambda.rs

@@ -0,0 +1,96 @@
+use opentelemetry::KeyValue;
+use opentelemetry_sdk::resource::ResourceDetector;
+use opentelemetry_sdk::Resource;
+use opentelemetry_semantic_conventions as semconv;
+use std::env;
+use std::time::Duration;
+
+// For a complete list of reserved environment variables in Lambda, see:
+// https://docs.aws.amazon.com/lambda/latest/dg/configuration-envvars.html
+const AWS_LAMBDA_FUNCTION_NAME_ENV_VAR: &str = "AWS_LAMBDA_FUNCTION_NAME";
+const AWS_REGION_ENV_VAR: &str = "AWS_REGION";
+const AWS_LAMBDA_FUNCTION_VERSION_ENV_VAR: &str = "AWS_LAMBDA_FUNCTION_VERSION";
+const AWS_LAMBDA_LOG_STREAM_NAME_ENV_VAR: &str = "AWS_LAMBDA_LOG_STREAM_NAME";
+const AWS_LAMBDA_MEMORY_LIMIT_ENV_VAR: &str = "AWS_LAMBDA_FUNCTION_MEMORY_SIZE";
+
+/// Resource detector that collects resource information from AWS Lambda environment.
+pub struct LambdaResourceDetector;
+
+impl ResourceDetector for LambdaResourceDetector {
+    fn detect(&self, _: Duration) -> Resource {
+        let lambda_name = env::var(AWS_LAMBDA_FUNCTION_NAME_ENV_VAR).unwrap_or_default();
+        // If no lambda name is provided, it means that
+        // we're not on a Lambda environment, so we return empty resource.
+        if lambda_name.is_empty() {
+            return Resource::empty();
+        }
+
+        let aws_region = env::var(AWS_REGION_ENV_VAR).unwrap_or_default();
+        let function_version = env::var(AWS_LAMBDA_FUNCTION_VERSION_ENV_VAR).unwrap_or_default();
+        let function_memory_limit = env::var(AWS_LAMBDA_MEMORY_LIMIT_ENV_VAR).unwrap_or_default();
+        // Instance attributes corresponds to the log stream name for AWS Lambda;
+        // See the FaaS resource specification for more details.
+        let instance = env::var(AWS_LAMBDA_LOG_STREAM_NAME_ENV_VAR).unwrap_or_default();
+
+        let attributes = [
+            KeyValue::new(semconv::resource::CLOUD_PROVIDER, "aws"),
+            KeyValue::new(semconv::resource::CLOUD_REGION, aws_region),
+            KeyValue::new(semconv::resource::FAAS_INSTANCE, instance),
+            KeyValue::new(semconv::resource::FAAS_NAME, lambda_name),
+            KeyValue::new(semconv::resource::FAAS_VERSION, function_version),
+            KeyValue::new(semconv::resource::FAAS_MAX_MEMORY, function_memory_limit),
+        ];
+
+        Resource::new(attributes)
+    }
+}
+
+#[cfg(test)]
+#[cfg(feature = "aws-lambda")]
+mod tests {
+    use super::*;
+    use sealed_test::prelude::*;
+    use std::env::{remove_var, set_var};
+
+    #[sealed_test]
+    fn test_aws_lambda_detector() {
+        set_var(AWS_LAMBDA_FUNCTION_NAME_ENV_VAR, "my-lambda-function");
+        set_var(AWS_REGION_ENV_VAR, "eu-west-3");
+        set_var(AWS_LAMBDA_FUNCTION_VERSION_ENV_VAR, "$LATEST");
+        set_var(
+            AWS_LAMBDA_LOG_STREAM_NAME_ENV_VAR,
+            "2023/01/01/[$LATEST]5d1edb9e525d486696cf01a3503487bc",
+        );
+        set_var(AWS_LAMBDA_MEMORY_LIMIT_ENV_VAR, "128");
+
+        let expected = Resource::new([
+            KeyValue::new(semconv::resource::CLOUD_PROVIDER, "aws"),
+            KeyValue::new(semconv::resource::CLOUD_REGION, "eu-west-3"),
+            KeyValue::new(
+                semconv::resource::FAAS_INSTANCE,
+                "2023/01/01/[$LATEST]5d1edb9e525d486696cf01a3503487bc",
+            ),
+            KeyValue::new(semconv::resource::FAAS_NAME, "my-lambda-function"),
+            KeyValue::new(semconv::resource::FAAS_VERSION, "$LATEST"),
+            KeyValue::new(semconv::resource::FAAS_MAX_MEMORY, "128"),
+        ]);
+
+        let detector = LambdaResourceDetector {};
+        let got = detector.detect(Duration::from_secs(0));
+
+        assert_eq!(expected, got);
+
+        remove_var(AWS_LAMBDA_FUNCTION_NAME_ENV_VAR);
+        remove_var(AWS_REGION_ENV_VAR);
+        remove_var(AWS_LAMBDA_FUNCTION_VERSION_ENV_VAR);
+        remove_var(AWS_LAMBDA_LOG_STREAM_NAME_ENV_VAR);
+        remove_var(AWS_LAMBDA_MEMORY_LIMIT_ENV_VAR);
+    }
+
+    #[sealed_test]
+    fn test_aws_lambda_detector_returns_empty_if_no_lambda_environment() {
+        let detector = LambdaResourceDetector {};
+        let got = detector.detect(Duration::from_secs(0));
+        assert_eq!(Resource::empty(), got);
+    }
+}

opentelemetry-resource-detectors/src/lib.rs

@@ -6,10 +6,14 @@
 //! - [`OsResourceDetector`] - detect OS from runtime.
 //! - [`ProcessResourceDetector`] - detect process information.
 //! - [`HostResourceDetector`] - detect unique host ID.
+//! - [`LambdaResourceDetector`] - detect resource metadata from an AWS Lambda environment.
+mod aws;
 mod host;
 mod os;
 mod process;
 
+#[cfg(feature = "aws-lambda")]
+pub use aws::LambdaResourceDetector;
 pub use host::HostResourceDetector;
 pub use os::OsResourceDetector;
 pub use process::ProcessResourceDetector;