update attributes for pipe and backend stage

Author: dhontecillas

README.md

@@ -121,6 +121,20 @@ At the router level we have 3 main options:
 }
 ```
 
+##### Metrics
+
+- `router-response-latency`: histogram of the time it takes to produce the response.
+    Attributes:
+    - `http.response.status_code`: status code of the produced response
+    - `url.path`: the matched endpoint path
+    - `krakend.stage`: always with value `router`
+- `router-response-size`: histogram of the size of the body produced for the response.
+    Attributes:
+    - `http.response.status_code`: status code of the produced response
+    - `url.path`: the matched endpoint path
+    - `kakend.stage`: always with value `router`
+
+
 #### pipe
 
 At the pipe level we only have 2 options:
@@ -135,6 +149,26 @@ At the pipe level we only have 2 options:
 }
 ```
 
+##### Metrics
+
+- `stage-duration`: histogram of the time it takes to produce the response.
+    Attributes:
+    - `url.path`: the matched endpoint path that **krakend is serving** (is different
+        than in `backend`, krakend stage, when this property is the path
+        for the backend we are targetting).
+    - `krakend.stage`: always with value `pipe`
+
+##### Traces
+
+Attributes:
+
+- `krakend.stage`: always with value `pipe`
+- `complete`: a `true` / `false` value to know when a response is complete (all
+    backends returned a successful response).
+- `canceled`: if appears, will always be `true`, and indicates a request
+    that has been canceled (usually when parallel requests are used).
+- `error`: in case an error happened, the description of the error.
+
 #### backend
 
 At the backend level is where we have more granularity selecting the information
@@ -186,6 +220,31 @@ For both, the `metrics` and `traces` part, we can select the same options:
 }
 ```
 
+##### Metrics
+
+- `stage-duration`: histogram of the time it takes to produce the response. Controlled
+  by the `disable_stage` flag (if set to `true` this metric will not appear).
+    Attributes:
+    - `url.path`: the matched endpoint path that **krakend is serving** (is different
+        than in `backend`, krakend stage, when this property is the path
+        for the backend we are targetting).
+    - `krakend.stage`: always with value `backend`
+    - `krakend.endpoint`: this attribute is set to the krakend exposed endpoint that 
+        is the "parent" of the backend request.
+    - `server.address`: the target host (in case more than one are provided, those
+        are joined with `_`).
+
+##### Traces
+
+**Stage Span** attributes (controlled by the `disable_stage` flag: will not appear if set to `true`):
+
+- `krakend.stage`: always with value `pipe`
+- `complete`: a `true` / `false` value to know when a response is complete (all
+    backends returned a successful response).
+- `canceled`: if appears, will always be `true`, and indicates a request
+    that has been canceled (usually when parallel requests are used).
+- `error`: in case an error happened, the description of the error.
+
 ### Instance 
 
 Given that any Exporter could implement both traces and metrics, we might want

lura/proxy.go

@@ -3,10 +3,12 @@ package lura
 import (
 	"context"
 	"errors"
+	"strings"
 	"time"
 
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/semconv/v1.21.0"
 	"go.opentelemetry.io/otel/trace"
 
 	"github.com/luraproject/lura/v2/config"
@@ -34,9 +36,11 @@ var (
 	)
 )
 
-// Middleare creates a proxy that instruments the proxy it wraps by creating an span if enabled,
+// Middleware creates a proxy that instruments the proxy it wraps by creating an span if enabled,
 // and report the duration of this stage in metrics if enabled.
-func Middleware(name string, stage string, gsf state.GetterFn, metricsEnabled bool, tracesEnabled bool) proxy.Middleware {
+func Middleware(staticAttrs []attribute.KeyValue, gsf state.GetterFn, metricsEnabled bool, tracesEnabled bool,
+	spanName string) proxy.Middleware {
+
 	if gsf == nil {
 		gsf = state.GlobalState
 	}
@@ -62,10 +66,7 @@ func Middleware(name string, stage string, gsf state.GetterFn, metricsEnabled bo
 		if err != nil {
 			reportMetrics = false
 		}
-		metricAttrs := metric.WithAttributes(
-			attribute.String("krakend.name", name),
-			attribute.String("krakend.stage", stage),
-		)
+		metricAttrs := metric.WithAttributes(staticAttrs...)
 
 		reportTrace := tracesEnabled
 		tracer := gs.Tracer()
@@ -83,15 +84,15 @@ func Middleware(name string, stage string, gsf state.GetterFn, metricsEnabled bo
 					ctx = trace.ContextWithSpan(ctx, ginSpan)
 				}
 				// start the new Context, for the stage:
-				ctx, span = tracer.Start(ctx, name)
+				ctx, span = tracer.Start(ctx, spanName)
 				if ginSpan != nil {
 					// we need to update the key with the new span, otherwise, deeper middlewares
 					// (like when from pipe -> proxy), would get the span from the parent, instead
 					// of the one in the context
 					ctx = context.WithValue(ctx, state.KrakenDContextOTELStrKey, span)
 				}
 				// TODO: CHECK that we have this attribute set !!
-				span.SetAttributes(attribute.String("krakend.stage", stage))
+				span.SetAttributes(staticAttrs...)
 			}
 
 			startedAt := time.Now()
@@ -154,7 +155,11 @@ func ProxyFactory(pf proxy.Factory, gsfn state.GetterFn, opts *kotelconfig.PipeO
 		// in original opencensus, we prefixed the endpoint with a `pipe` prefix
 		// return Middleware("pipe-" + cfg.Endpoint)(next), nil
 		urlPattern := kotelconfig.NormalizeURLPattern(cfg.Endpoint)
-		return Middleware(urlPattern, "pipe", gsfn, metricsEnabled, tracesEnabled)(next), nil
+		staticAttrs := []attribute.KeyValue{
+			semconv.URLPath(urlPattern),
+			attribute.String("krakend.stage", "pipe"),
+		}
+		return Middleware(staticAttrs, gsfn, metricsEnabled, tracesEnabled, urlPattern)(next), nil
 	}
 }
 
@@ -177,6 +182,17 @@ func BackendFactory(bf proxy.BackendFactory, gsfn state.GetterFn, opts *kotelcon
 			}
 		}
 		urlPattern := kotelconfig.NormalizeURLPattern(cfg.URLPattern)
-		return Middleware(urlPattern, "backend", gsfn, metricsEnabled, tracesEnabled)(next)
+		parentEndpoint := kotelconfig.NormalizeURLPattern(cfg.ParentEndpoint)
+		hosts := strings.Join(cfg.Host, "_")
+		// TODO: check if we want to have the hosts as static attribute
+		staticAttrs := []attribute.KeyValue{
+			semconv.URLPath(urlPattern),
+			attribute.String("krakend.stage", "backend"),
+			attribute.String("krakend.endpoint", parentEndpoint),
+			semconv.ServerAddress(hosts),
+		}
+		// TODO: check if we want to have the hosts, to paths that are the same, but for different hosts
+		spanName := strings.Join(cfg.Host, "_") + urlPattern
+		return Middleware(staticAttrs, gsfn, metricsEnabled, tracesEnabled, spanName)(next)
 	}
 }