Added k8s ResourceDetector (#122)

Author: RichardChukwu

opentelemetry-resource-detectors/src/k8s.rs

@@ -0,0 +1,24 @@
+use opentelemetry::sdk::resource::{Resource, ResourceDetector};
+use opentelemetry_semantic_conventions::resource;
+use std::env;
+use std::time::Duration;
+
+/// A resource detector for Kubernetes environment variables.
+pub struct K8sResourceDetector;
+
+impl ResourceDetector for K8sResourceDetector {
+    /// Detect Kubernetes-related environment variables and return a Resource.
+    fn detect(&self, _timeout: Duration) -> Resource {
+        // Attempt to read Kubernetes-specific environment variables.
+        let pod_name = env::var("K8S_POD_NAME").unwrap_or_else(|_| "unknown_pod".to_string());
+        let namespace_name = env::var("K8S_NAMESPACE_NAME").unwrap_or_else(|_| "unknown_namespace".to_string());
+        let node_name = env::var("K8S_NODE_NAME").unwrap_or_else(|_| "unknown_node".to_string());
+
+        // Create a Resource with Kubernetes attributes.
+        Resource::new(vec![
+            resource::K8S_POD_NAME.string(pod_name),
+            resource::K8S_NAMESPACE_NAME.string(namespace_name),
+            resource::K8S_NODE_NAME.string(node_name),
+        ])
+    }
+}

opentelemetry-resource-detectors/src/k8stest.rs

@@ -0,0 +1,58 @@
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::time::Duration;
+    use temp_env;
+
+    #[test]
+    fn test_k8s_resource_detector_with_env_vars() {
+        // Temporarily set environment variables for the test
+        temp_env::with_vars(
+            [
+                ("K8S_POD_NAME", Some("test-pod")),
+                ("K8S_NAMESPACE_NAME", Some("test-namespace")),
+                ("K8S_NODE_NAME", Some("test-node")),
+            ],
+            || {
+                // Create the K8sResourceDetector
+                let detector = K8sResourceDetector::new();
+                // Use the detector to fetch the resources
+                let resource = detector.detect(Duration::from_secs(5));
+                
+                // Assert that the detected resource attributes match the expected values
+                assert_eq!(
+                    resource,
+                    Resource::new(vec![
+                        KeyValue::new("k8s.pod.name", "test-pod"),
+                        KeyValue::new("k8s.namespace.name", "test-namespace"),
+                        KeyValue::new("k8s.node.name", "test-node"),
+                    ])
+                );
+            },
+        );
+    }
+
+    #[test]
+    fn test_k8s_resource_detector_with_missing_env_vars() {
+        // Temporarily set only one environment variable to test defaults
+        temp_env::with_vars(
+            [("K8S_POD_NAME", Some("test-pod"))],
+            || {
+                // Create the K8sResourceDetector
+                let detector = K8sResourceDetector::new();
+                // Use the detector to fetch the resources
+                let resource = detector.detect(Duration::from_secs(5));
+
+                // Assert that missing values use the default "unknown" values
+                assert_eq!(
+                    resource,
+                    Resource::new(vec![
+                        KeyValue::new("k8s.pod.name", "test-pod"),
+                        KeyValue::new("k8s.namespace.name", "unknown_namespace"),
+                        KeyValue::new("k8s.node.name", "unknown_node"),
+                    ])
+                );
+            },
+        );
+    }
+}