Add inference_extension_info metric for project metadata (#744)

Start with just commit, version information will be added in a follow-up
change.

Verified:
```
inference_extension_info{commit="60f8c57bb95b656a75d27564d5ff01c060bcdba5"} 1
```

Author: JeffLuoo

Dockerfile

@@ -19,8 +19,9 @@ COPY cmd ./cmd
 COPY pkg ./pkg
 COPY internal ./internal
 COPY api ./api
+COPY .git ./.git
 WORKDIR /src/cmd/epp
-RUN go build -o /epp
+RUN go build -buildvcs=true -o /epp
 
 ## Multistage deploy
 FROM ${BASE_IMAGE}

cmd/epp/main.go

@@ -250,6 +250,8 @@ func registerHealthServer(mgr manager.Manager, logger logr.Logger, ds datastore.
 func registerMetricsHandler(mgr manager.Manager, port int, cfg *rest.Config) error {
 	metrics.Register()
 
+	metrics.RecordInferenceExtensionInfo()
+
 	// Init HTTP server.
 	h, err := metricsHandlerWithAuthenticationAndAuthorization(cfg)
 	if err != nil {

pkg/epp/metrics/metrics.go

@@ -18,6 +18,7 @@ package metrics
 
 import (
 	"context"
+	"runtime/debug"
 	"sync"
 	"time"
 
@@ -31,6 +32,12 @@ const (
 	InferenceModelComponent = "inference_model"
 	InferencePoolComponent  = "inference_pool"
 	EPPComponent            = "endpoint_picker"
+	InferenceExtension      = "inference_extension"
+)
+
+var (
+	// The git hash of the latest commit in the build.
+	CommitHash string
 )
 
 var (
@@ -191,6 +198,17 @@ var (
 		},
 		[]string{"plugin_type", "plugin_name"},
 	)
+
+	// Info Metrics
+	InferenceExtensionInfo = compbasemetrics.NewGaugeVec(
+		&compbasemetrics.GaugeOpts{
+			Subsystem:      InferenceExtension,
+			Name:           "info",
+			Help:           "General information of the current build of Inference Extension.",
+			StabilityLevel: compbasemetrics.ALPHA,
+		},
+		[]string{"commit"},
+	)
 )
 
 var registerMetrics sync.Once
@@ -213,6 +231,8 @@ func Register() {
 		legacyregistry.MustRegister(inferencePoolReadyPods)
 
 		legacyregistry.MustRegister(SchedulerPluginProcessingLatencies)
+
+		legacyregistry.MustRegister(InferenceExtensionInfo)
 	})
 }
 
@@ -315,3 +335,27 @@ func RecordinferencePoolReadyPods(name string, runningPods float64) {
 func RecordSchedulerPluginProcessingLatency(pluginType, pluginName string, duration time.Duration) {
 	SchedulerPluginProcessingLatencies.WithLabelValues(pluginType, pluginName).Observe(duration.Seconds())
 }
+
+func RecordInferenceExtensionInfo() {
+	if CommitHash != "" {
+		InferenceExtensionInfo.WithLabelValues(CommitHash).Set(1)
+	}
+}
+
+func init() {
+	info, ok := debug.ReadBuildInfo()
+	if !ok {
+		return
+	}
+
+	var Commit = func(i *debug.BuildInfo) string {
+		for _, setting := range i.Settings {
+			if setting.Key == "vcs.revision" {
+				return setting.Value
+			}
+		}
+		return ""
+	}(info)
+
+	CommitHash = Commit
+}

site-src/guides/metrics.md

@@ -35,6 +35,8 @@ curl -i ${IP}:${PORT}/v1/completions -H 'Content-Type: application/json' -d '{
 | inference_pool_average_kv_cache_utilization  | Gauge            | The average kv cache utilization for an inference server pool.    | `name`=<inference-pool-name>                                                 | ALPHA       |
 | inference_pool_average_queue_size            | Gauge            | The average number of requests pending in the model server queue. | `name`=<inference-pool-name>                                                 | ALPHA       |
 | inference_pool_ready_pods                    | Gauge            | The number of ready pods for an inference server pool.            | `name`=<inference-pool-name>                                                 | ALPHA       |
+| inference_extension_info                     | Gauge            | The general information of the current build.                     | `commit`=<hash-of-the-build>                                                 | ALPHA       |
+
 
 ## Scrape Metrics