Change endpoint format for per-bucket metrics (#19655)

Per-bucket metrics endpoints always start with /bucket and the bucket
name is appended to the path. e.g. if the collector path is /bucket/api,
the endpoint for the bucket "mybucket" would be
/minio/metrics/v3/bucket/api/mybucket

Change the existing bucket api endpoint accordingly from /api/bucket to
/bucket/api

cmd/metrics-v3-handler.go

@@ -221,18 +221,15 @@ func (h *metricsV3Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	pathComponents := mux.Vars(r)["pathComps"]
 	isListingRequest := r.Form.Has("list")
 
-	// Parse optional buckets query parameter.
+	buckets := []string{}
-	bucketsParam := r.Form["buckets"]
+	if strings.HasPrefix(pathComponents, "/bucket/") {
-	buckets := make([]string, 0, len(bucketsParam))
+		// bucket specific metrics, extract the bucket name from the path.
-	for _, bp := range bucketsParam {
+		// it's the last part of the path. e.g. /bucket/api/<bucket-name>
-		bp = strings.TrimSpace(bp)
+		bucketIdx := strings.LastIndex(pathComponents, "/")
-		if bp == "" {
+		buckets = append(buckets, pathComponents[bucketIdx+1:])
-			continue
+		// remove bucket from pathComponents as it is dyanamic and
-		}
+		// hence not included in the collector path.
-		splits := strings.Split(bp, ",")
+		pathComponents = pathComponents[:bucketIdx]
-		for _, split := range splits {
-			buckets = append(buckets, strings.TrimSpace(split))
-		}
 	}
 
 	innerHandler := h.handle(pathComponents, isListingRequest, buckets)

cmd/metrics-v3.go

@@ -29,9 +29,13 @@ import (
 //
 // These are paths under the top-level /minio/metrics/v3 metrics endpoint. Each
 // of these paths returns a set of V3 metrics.
+//
+// Per-bucket metrics endpoints always start with /bucket and the bucket name is
+// appended to the path. e.g. if the collector path is /bucket/api, the endpoint
+// for the bucket "mybucket" would be /minio/metrics/v3/bucket/api/mybucket
 const (
 	apiRequestsCollectorPath collectorPath = "/api/requests"
-	apiBucketCollectorPath   collectorPath = "/api/bucket"
+	apiBucketCollectorPath   collectorPath = "/bucket/api"
 
 	systemNetworkInternodeCollectorPath collectorPath = "/system/network/internode"
 	systemDriveCollectorPath            collectorPath = "/system/drive"

docs/metrics/v3.md

@@ -86,18 +86,18 @@ The standard metrics group for GoCollector is not shown below.
 | `minio_api_requests_traffic_sent_bytes`        | `counter` | Total number of bytes sent                              | `type,pool_index,server`         |
 | `minio_api_requests_traffic_received_bytes`    | `counter` | Total number of bytes received                          | `type,pool_index,server`         |
 
-### `/api/bucket`
+### `/bucket/api`
 
 | Name                                         | Type      | Help                                                             | Labels                                  |
 |----------------------------------------------|-----------|------------------------------------------------------------------|-----------------------------------------|
-| `minio_api_bucket_traffic_received_bytes`    | `counter` | Total number of bytes sent for a bucket                          | `bucket,type,server,pool_index`         |
+| `minio_bucket_api_traffic_received_bytes`    | `counter` | Total number of bytes sent for a bucket                          | `bucket,type,server,pool_index`         |
-| `minio_api_bucket_traffic_sent_bytes`        | `counter` | Total number of bytes received for a bucket                      | `bucket,type,server,pool_index`         |
+| `minio_bucket_api_traffic_sent_bytes`        | `counter` | Total number of bytes received for a bucket                      | `bucket,type,server,pool_index`         |
-| `minio_api_bucket_inflight_total`            | `gauge`   | Total number of requests currently in flight for a bucket        | `bucket,name,type,server,pool_index`    |
+| `minio_bucket_api_inflight_total`            | `gauge`   | Total number of requests currently in flight for a bucket        | `bucket,name,type,server,pool_index`    |
-| `minio_api_bucket_total`                     | `counter` | Total number of requests for a bucket                            | `bucket,name,type,server,pool_index`    |
+| `minio_bucket_api_total`                     | `counter` | Total number of requests for a bucket                            | `bucket,name,type,server,pool_index`    |
-| `minio_api_bucket_canceled_total`            | `counter` | Total number of requests canceled by the client for a bucket     | `bucket,name,type,server,pool_index`    |
+| `minio_bucket_api_canceled_total`            | `counter` | Total number of requests canceled by the client for a bucket     | `bucket,name,type,server,pool_index`    |
-| `minio_api_bucket_4xx_errors_total`          | `counter` | Total number of requests with 4xx errors for a bucket            | `bucket,name,type,server,pool_index`    |
+| `minio_bucket_api_4xx_errors_total`          | `counter` | Total number of requests with 4xx errors for a bucket            | `bucket,name,type,server,pool_index`    |
-| `minio_api_bucket_5xx_errors_total`          | `counter` | Total number of requests with 5xx errors for a bucket            | `bucket,name,type,server,pool_index`    |
+| `minio_bucket_api_5xx_errors_total`          | `counter` | Total number of requests with 5xx errors for a bucket            | `bucket,name,type,server,pool_index`    |
-| `minio_api_bucket_ttfb_seconds_distribution` | `counter` | Distribution of time to first byte across API calls for a bucket | `bucket,name,le,type,server,pool_index` |
+| `minio_bucket_api_ttfb_seconds_distribution` | `counter` | Distribution of time to first byte across API calls for a bucket | `bucket,name,le,type,server,pool_index` |
 
 ### `/system/drive`