Move API handlers to separate package

This makes the package split a little cleaner and easier to import the
HTTP handlers for other consumers.

vkubelet/api/stats.go

@@ -0,0 +1,39 @@
+package api
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+
+	"github.com/cpuguy83/strongerrors"
+	"github.com/pkg/errors"
+	stats "k8s.io/kubernetes/pkg/kubelet/apis/stats/v1alpha1"
+)
+
+// PodMetricsBackend is used in place of backend implementations to get k8s pod metrics.
+type PodMetricsBackend interface {
+	GetStatsSummary(context.Context) (*stats.Summary, error)
+}
+
+// PodMetricsHandlerFunc makes an HTTP handler for implementing the kubelet summary stats endpoint
+func PodMetricsHandlerFunc(b PodMetricsBackend) http.HandlerFunc {
+	return handleError(func(w http.ResponseWriter, req *http.Request) error {
+		stats, err := b.GetStatsSummary(req.Context())
+		if err != nil {
+			if errors.Cause(err) == context.Canceled {
+				return strongerrors.Cancelled(err)
+			}
+			return errors.Wrap(err, "error getting status from provider")
+		}
+
+		b, err := json.Marshal(stats)
+		if err != nil {
+			return strongerrors.Unknown(errors.Wrap(err, "error marshalling stats"))
+		}
+
+		if _, err := w.Write(b); err != nil {
+			return strongerrors.Unknown(errors.Wrap(err, "could not write to client"))
+		}
+		return nil
+	})
+}