Ignore clearmodes when comparing label names

We don't care about the clear mode label when we're comparing label names because that
label will be ultimately stripped out before merging. Thus, when we compare new and old label
names for equivalency, this commit fixes that check by simply skipping the clearmode if it
exists in the new push

src/aggregator.rs

@@ -321,6 +321,22 @@ fn add_extra_labels(mut exposition: MetricsExposition<PrometheusType, Prometheus
     return Ok(exposition);
 }
 
+// are_label_names_equivalent checks wether two sets of label names are equivalent,
+// minus label names that are irrelevant to the final push (basically just the clearmode)
+fn are_label_names_equivalent(existing: &[String], new: &[String]) -> bool {
+    for new_label in new.iter() {
+        if new_label == CLEARMODE_LABEL_NAME {
+            continue
+        }
+
+        if !existing.contains(new_label) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
 impl Aggregator {
     pub fn new() -> Aggregator {
         return Aggregator {
@@ -337,7 +353,7 @@ impl Aggregator {
         for (name, metrics) in metrics.families {
             match families.get_mut(&name) {
                 Some(f) => {
-                    if f.base_family.get_label_names() != metrics.get_label_names() {
+                    if !are_label_names_equivalent(f.base_family.get_label_names(), metrics.get_label_names()) {
                         // The new push has different label names - abort
                         return Err(AggregationError::Error("invalid push - new push has different label names than the existing family".to_string()))
                     }

src/aggregator_test.rs

@@ -146,4 +146,7 @@ async fn test_push_with_different_label_names() {
     assert!(agg.parse_and_merge("requests_num_total{job=\"test\"} 1\n", &HashMap::new()).await.is_err(), "failed to reject invalid label name");
     assert!(agg.parse_and_merge("requests_num_total{bar=\"test\"} 1\n", &HashMap::new()).await.is_err(), "failed to reject invalid label name");
     assert!(agg.parse_and_merge("requests_num_total{LAMBDA_NAME=\"test_function\"} 1\n", &HashMap::new()).await.is_ok(), "failed to parse metric with same label name");
+
+    assert!(agg.parse_and_merge("requests_num_total2{clearmode=\"mean5m\"} 1\n", &HashMap::new()).await.is_ok(), "failed to add metric with clearmode");
+    assert!(agg.parse_and_merge("requests_num_total2{clearmode=\"mean5m\"} 1\n", &HashMap::new()).await.is_ok(), "failed to add second metric with clearmode");
 }