refactor metrics naming for wasm

Signed-off-by: shawnh2 <shawnhxh@outlook.com>

internal/metrics/otel_label.go

@@ -18,11 +18,11 @@ var (
 )
 
 const (
-	StatusSuccess = "Success"
-	StatusFailure = "Failure"
+	StatusSuccess = "success"
+	StatusFailure = "failure"
 
-	ReasonError    = "Error"
-	ReasonConflict = "Conflict"
+	ReasonError    = "error"
+	ReasonConflict = "conflict"
 )
 
 // A Label provides a named dimension for a Metric.

internal/wasm/cache.go

@@ -239,7 +239,7 @@ func (c *localFileCache) getOrFetch(key cacheKey, opts GetOptions) (*cacheEntry,
 		// Download the Wasm module with http fetcher.
 		b, err = c.httpFetcher.Fetch(ctx, key.downloadURL, insecure)
 		if err != nil {
-			wasmRemoteFetchCount.With(resultTag.Value(downloadFailure)).Increment()
+			wasmRemoteFetchTotal.WithFailure(reasonDownloadError).Increment()
 			return nil, err
 		}
 
@@ -251,7 +251,7 @@ func (c *localFileCache) getOrFetch(key cacheKey, opts GetOptions) (*cacheEntry,
 			isPrivate = true
 		}
 		if imageBinaryFetcher, dChecksum, err = c.prepareFetch(ctx, u, insecure, opts); err != nil {
-			wasmRemoteFetchCount.With(resultTag.Value(manifestFailure)).Increment()
+			wasmRemoteFetchTotal.WithFailure(reasonManifestError).Increment()
 			return nil, fmt.Errorf("could not fetch Wasm OCI image: %w", err)
 		}
 	default:
@@ -261,7 +261,7 @@ func (c *localFileCache) getOrFetch(key cacheKey, opts GetOptions) (*cacheEntry,
 	// If the checksum is provided, check if it matches the downloaded binary.
 	if key.checksum != "" {
 		if dChecksum != key.checksum {
-			wasmRemoteFetchCount.With(resultTag.Value(checksumMismatch)).Increment()
+			wasmRemoteFetchTotal.WithFailure(reasonChecksumMismatch).Increment()
 			return nil, fmt.Errorf("module downloaded from %v has checksum %v, which does not match: %v", key.downloadURL, dChecksum, key.checksum)
 		}
 	} else {
@@ -272,17 +272,18 @@ func (c *localFileCache) getOrFetch(key cacheKey, opts GetOptions) (*cacheEntry,
 	if imageBinaryFetcher != nil {
 		b, err = imageBinaryFetcher()
 		if err != nil {
-			wasmRemoteFetchCount.With(resultTag.Value(downloadFailure)).Increment()
+			wasmRemoteFetchTotal.WithFailure(reasonDownloadError).Increment()
 			return nil, fmt.Errorf("could not fetch Wasm binary: %w", err)
 		}
 	}
 
 	if !isValidWasmBinary(b) {
-		wasmRemoteFetchCount.With(resultTag.Value(fetchFailure)).Increment()
+		wasmRemoteFetchTotal.WithFailure(reasonFetchError).Increment()
 		return nil, fmt.Errorf("fetched Wasm binary from %s is invalid", key.downloadURL)
 	}
 
-	wasmRemoteFetchCount.With(resultTag.Value(fetchSuccess)).Increment()
+	wasmRemoteFetchTotal.WithSuccess().Increment()
+
 	return c.addEntry(key, b, isPrivate)
 }
 
@@ -365,7 +366,9 @@ func (c *localFileCache) addEntry(key cacheKey, wasmModule []byte, isPrivate boo
 	}
 	ce.referencingURLs.Insert(key.downloadURL)
 	c.modules[key.moduleKey] = &ce
+
 	wasmCacheEntries.Record(float64(len(c.modules)))
+
 	return &ce, nil
 }
 
@@ -378,7 +381,7 @@ func (c *localFileCache) getEntry(key cacheKey, pullPolicy PullPolicy, u *url.UR
 	c.mux.Lock()
 	defer func() {
 		c.mux.Unlock()
-		wasmCacheLookupCount.With(hitTag.Value(strconv.FormatBool(cacheHit))).Increment()
+		wasmCacheLookupTotal.With(hitTag.Value(strconv.FormatBool(cacheHit))).Increment()
 	}()
 
 	// If no checksum is provided, check if a wasm module with the same downloading URL has been pulled before.

internal/wasm/metrics.go

@@ -21,33 +21,29 @@ package wasm
 
 import "github.com/envoyproxy/gateway/internal/metrics"
 
-// Const strings for label value.
 const (
-	// For remote fetch metric.
-	fetchSuccess     = "success"
-	fetchFailure     = "fetch_failure"
-	downloadFailure  = "download_failure"
-	manifestFailure  = "manifest_failure"
-	checksumMismatch = "checksum_mismatched"
+	reasonFetchError       = "fetch_error"
+	reasonDownloadError    = "download_error"
+	reasonManifestError    = "manifest_error"
+	reasonChecksumMismatch = "checksum_mismatched"
 )
 
 var (
-	hitTag    = metrics.NewLabel("hit")
-	resultTag = metrics.NewLabel("result")
+	hitTag = metrics.NewLabel("hit")
 
 	wasmCacheEntries = metrics.NewGauge(
 		"wasm_cache_entries",
-		"number of Wasm remote fetch cache entries.",
+		"Number of Wasm remote fetch cache entries.",
 	)
 
-	wasmCacheLookupCount = metrics.NewCounter(
-		"wasm_cache_lookup_count",
-		"number of Wasm remote fetch cache lookups.",
+	wasmCacheLookupTotal = metrics.NewCounter(
+		"wasm_cache_lookup_total",
+		"Total number of Wasm remote fetch cache lookups.",
 	)
 
-	wasmRemoteFetchCount = metrics.NewCounter(
-		"wasm_remote_fetch_count",
-		"number of Wasm remote fetches and results, including success, download failure, and checksum mismatch.",
+	wasmRemoteFetchTotal = metrics.NewCounter(
+		"wasm_remote_fetch_total",
+		"Total number of Wasm remote fetches and results.",
 	)
 )
 

site/content/en/latest/tasks/observability/gateway-exported-metrics.md

@@ -81,4 +81,17 @@ Each metric includes the `kind` label to identify the corresponding resources be
 
 Metrics may also include `name` and `namespace` label to identify the name and namespace of corresponding Infrastructure Manager.
 
+## Wasm
+
+Envoy Gateway monitors the status of Wasm remote fetch cache.
+
+| Name                      | Description                                      |
+|---------------------------|--------------------------------------------------|
+| `wasm_cache_entries`      | Number of Wasm remote fetch cache entries.       | 
+| `wasm_cache_lookup_total` | Total number of Wasm remote fetch cache lookups. |
+| `wasm_remote_fetch_total` | Total number of Wasm remote fetches and results. |
+
+For metric `wasm_cache_lookup_total`, we are using `hit` label (boolean) to indicate whether the Wasm cache has been hit.
+
+
 [prom-format]: https://prometheus.io/docs/instrumenting/exposition_formats/#text-based-format