Add _dd.tags.function to top level trace tags hashmap.

Author: purple4reina

bottlecap/src/tags/lambda/tags.rs

@@ -44,6 +44,8 @@ const SERVICE_KEY: &str = "service";
 const COMPUTE_STATS_KEY: &str = "_dd.compute_stats";
 // ComputeStatsValue is the tag value indicating trace stats should be computed
 const COMPUTE_STATS_VALUE: &str = "1";
+// FunctionTagsKey is the tag key for a function's tags to be set on the top level tracepayload
+const FUNCTION_TAGS_KEY: &str = "_dd.tags.function";
 // TODO(astuyve) decide what to do with the version
 const EXTENSION_VERSION_KEY: &str = "dd_extension_version";
 // TODO(duncanista) figure out a better way to not hardcode this
@@ -249,6 +251,17 @@ impl Lambda {
     pub fn get_tags_map(&self) -> &hash_map::HashMap<String, String> {
         &self.tags_map
     }
+
+    #[must_use]
+    pub fn get_function_tags_map(&self) -> hash_map::HashMap<String, String> {
+        let tags = self
+            .tags_map
+            .iter()
+            .map(|(k, v)| format!("{k}:{v}"))
+            .collect::<Vec<String>>()
+            .join(",");
+        hash_map::HashMap::from_iter([(FUNCTION_TAGS_KEY.to_string(), tags)])
+    }
 }
 
 #[cfg(test)]

bottlecap/src/tags/provider.rs

@@ -56,6 +56,11 @@ impl Provider {
     pub fn get_tags_map(&self) -> &hash_map::HashMap<String, String> {
         self.tag_provider.get_tags_map()
     }
+
+    #[must_use]
+    pub fn get_function_tags_map(&self) -> hash_map::HashMap<String, String> {
+        self.tag_provider.get_function_tags_map()
+    }
 }
 
 trait GetTags {

bottlecap/src/traces/trace_processor.rs

@@ -137,6 +137,9 @@ impl TraceProcessor for ServerlessTraceProcessor {
             },
             true,
         );
+        payload
+            .tags
+            .extend(tags_provider.get_function_tags_map().clone());
         let intake_url = trace_intake_url(&config.site);
         let endpoint = Endpoint {
             url: hyper::Uri::from_str(&intake_url).expect("can't parse trace intake URL, exiting"),