(Fix) telemetry: allow overriding of service.version (#5689)

Co-authored-by: bryn <bryn@apollographql.com>

.changesets/fix_bryn_service_version.md

@@ -0,0 +1,17 @@
+### Allow overriding of service version ([PR #5689](https://github.com/apollographql/router/pull/5689))
+
+Previously `service.version` was not overridable via yaml and was ignored. It is now possible to set this explicitly which can be useful for users producing custom builds of the Router.
+
+For example:
+```yaml
+telemetry:
+  exporters:
+    tracing:
+      common:
+        resource:
+          service.version: 1.0
+```
+
+Overrides the version to `1.0`.
+
+By [@BrynCooke](https://github.com/BrynCooke) in https://github.com/apollographql/router/pull/5689

apollo-router/src/plugins/telemetry/resource.rs

@@ -11,6 +11,28 @@ use crate::plugins::telemetry::config::AttributeValue;
 const UNKNOWN_SERVICE: &str = "unknown_service";
 const OTEL_SERVICE_NAME: &str = "OTEL_SERVICE_NAME";
 
+/// This resource detector fills out things like the default service version and executable name.
+/// Users can always override them via config.
+struct StaticResourceDetector;
+impl ResourceDetector for StaticResourceDetector {
+    fn detect(&self, _timeout: Duration) -> Resource {
+        let mut config_resources = vec![];
+        config_resources.push(KeyValue::new(
+            opentelemetry_semantic_conventions::resource::SERVICE_VERSION,
+            std::env!("CARGO_PKG_VERSION"),
+        ));
+
+        // Some other basic resources
+        if let Some(executable_name) = executable_name() {
+            config_resources.push(KeyValue::new(
+                opentelemetry_semantic_conventions::resource::PROCESS_EXECUTABLE_NAME,
+                executable_name,
+            ));
+        }
+        Resource::new(config_resources)
+    }
+}
+
 struct EnvServiceNameDetector;
 // Used instead of SdkProvidedResourceDetector
 impl ResourceDetector for EnvServiceNameDetector {
@@ -42,6 +64,7 @@ pub(crate) trait ConfigResource {
         let resource = Resource::from_detectors(
             Duration::from_secs(0),
             vec![
+                Box::new(StaticResourceDetector),
                 Box::new(config_resource_detector),
                 Box::new(EnvResourceDetector::new()),
                 Box::new(EnvServiceNameDetector),
@@ -84,24 +107,10 @@ impl ResourceDetector for ConfigResourceDetector {
         let mut config_resources = vec![];
 
         // For config resources last entry wins
-
-        // Add any other resources from config
         for (key, value) in self.resources.iter() {
             config_resources.push(KeyValue::new(key.clone(), value.clone()));
         }
 
-        // Some other basic resources
-        config_resources.push(KeyValue::new(
-            opentelemetry_semantic_conventions::resource::SERVICE_VERSION,
-            std::env!("CARGO_PKG_VERSION"),
-        ));
-        if let Some(executable_name) = executable_name() {
-            config_resources.push(KeyValue::new(
-                opentelemetry_semantic_conventions::resource::PROCESS_EXECUTABLE_NAME,
-                executable_name,
-            ));
-        }
-
         // Service namespace
         if let Some(service_namespace) = self.service_namespace.clone() {
             config_resources.push(KeyValue::new(