Revert "[Refactor]: Core/API Split" (#1550)

Revert "[Refactor]: Core/API Split (#1506)"

This reverts commit ab7b4d5ee9.

metrics/metrics.go

@@ -0,0 +1,83 @@
+package metrics
+
+import (
+	"context"
+	"time"
+
+	"github.com/gofiber/fiber/v2"
+	"github.com/gofiber/fiber/v2/middleware/adaptor"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/exporters/prometheus"
+	api "go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/sdk/metric"
+)
+
+type Metrics struct {
+	meter         api.Meter
+	apiTimeMetric api.Float64Histogram
+}
+
+// setupOTelSDK bootstraps the OpenTelemetry pipeline.
+// If it does not return an error, make sure to call shutdown for proper cleanup.
+func SetupMetrics() (*Metrics, error) {
+	exporter, err := prometheus.New()
+	if err != nil {
+		return nil, err
+	}
+	provider := metric.NewMeterProvider(metric.WithReader(exporter))
+	meter := provider.Meter("github.com/go-skynet/LocalAI")
+
+	apiTimeMetric, err := meter.Float64Histogram("api_call", api.WithDescription("api calls"))
+	if err != nil {
+		return nil, err
+	}
+
+	return &Metrics{
+		meter:         meter,
+		apiTimeMetric: apiTimeMetric,
+	}, nil
+}
+
+func MetricsHandler() fiber.Handler {
+	return adaptor.HTTPHandler(promhttp.Handler())
+}
+
+type apiMiddlewareConfig struct {
+	Filter  func(c *fiber.Ctx) bool
+	metrics *Metrics
+}
+
+func APIMiddleware(metrics *Metrics) fiber.Handler {
+	cfg := apiMiddlewareConfig{
+		metrics: metrics,
+		Filter: func(c *fiber.Ctx) bool {
+			if c.Path() == "/metrics" {
+				return true
+			}
+			return false
+		},
+	}
+
+	return func(c *fiber.Ctx) error {
+		if cfg.Filter != nil && cfg.Filter(c) {
+			return c.Next()
+		}
+		path := c.Path()
+		method := c.Method()
+
+		start := time.Now()
+		err := c.Next()
+		elapsed := float64(time.Since(start)) / float64(time.Second)
+		cfg.metrics.ObserveAPICall(method, path, elapsed)
+		return err
+	}
+}
+
+func (m *Metrics) ObserveAPICall(method string, path string, duration float64) {
+	opts := api.WithAttributes(
+		attribute.String("method", method),
+		attribute.String("path", path),
+	)
+	m.apiTimeMetric.Record(context.Background(), duration, opts)
+}