Use strongerrors in provider implementations. (#403)

This ensures that we can catch certain types of errors from providers
and handle accordingly in the core. There is still more to do here to
improve that but this resolves an immediate need to know why a Delete
failed.

vic provider was not updated since I could not figure out where to get
this information.

providers/huawei/cci.go

@@ -14,6 +14,7 @@ import (
 	"os"
 	"time"
 
+	"github.com/cpuguy83/strongerrors"
 	"github.com/virtual-kubelet/virtual-kubelet/manager"
 	"github.com/virtual-kubelet/virtual-kubelet/providers/huawei/auth"
 	"k8s.io/api/core/v1"
@@ -237,8 +238,28 @@ func (p *CCIProvider) DeletePod(ctx context.Context, pod *v1.Pod) error {
 	if err = p.signRequest(r); err != nil {
 		return fmt.Errorf("Sign the request failed: %v", err)
 	}
-	_, err = p.client.HTTPClient.Do(r)
-	return err
+	resp, err := p.client.HTTPClient.Do(r)
+	if err != nil {
+		return err
+	}
+
+	return errorFromResponse(resp)
+}
+
+func errorFromResponse(resp *http.Response) error {
+	if resp.StatusCode < 400 {
+		return nil
+	}
+
+	body, _ := ioutil.ReadAll(io.LimitReader(resp.Body, 16*1024))
+	err := fmt.Errorf("error during http request, status=%d: %q", resp.StatusCode, string(body))
+
+	switch resp.StatusCode {
+	case http.StatusNotFound:
+		return strongerrors.NotFound(err)
+	default:
+		return err
+	}
 }
 
 // GetPod retrieves a pod by name from the huawei CCI provider.