Add IsTransientErr function

Checks if an error from an API server request is a transient server
issue such that a retry might succeed.

Signed-off-by: Tom Pantelis <[email protected]>

pkg/resource/errors.go

@@ -20,6 +20,7 @@ package resource
 
 import (
 	"errors"
+	"net"
 
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/api/meta"
@@ -68,3 +69,10 @@ func ExtractMissingNamespaceFromErr(err error) string {
 
 	return d.Name
 }
+
+func IsTransientErr(err error) bool {
+	// Check for errors indicating the server is temporarily busy (ServerTimeout and TooManyRequests). Also check for
+	// a net.OpError indicating a network connectivity issue. This is typically wrapped by a url.Error.
+	var netError *net.OpError
+	return apierrors.IsServerTimeout(err) || apierrors.IsTooManyRequests(err) || errors.As(err, &netError)
+}

pkg/resource/errors_test.go

@@ -19,10 +19,12 @@ limitations under the License.
 package resource_test
 
 import (
-	"errors"
+	"net"
+	"net/url"
 
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
+	"github.com/pkg/errors"
 	"github.com/submariner-io/admiral/pkg/resource"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/api/meta"
@@ -93,3 +95,47 @@ var _ = Describe("IsMissingNamespaceErr and ExtractMissingNamespaceFromErr", fun
 		})
 	})
 })
+
+var _ = Describe("IsTransientErr", func() {
+	When("the error is ServerTimeout", func() {
+		It("should return true", func() {
+			Expect(resource.IsTransientErr(apierrors.NewServerTimeout(schema.GroupResource{}, "get", 5))).To(BeTrue())
+		})
+	})
+
+	When("the error is TooManyRequests", func() {
+		It("should return true", func() {
+			Expect(resource.IsTransientErr(apierrors.NewTooManyRequests("", 5))).To(BeTrue())
+		})
+	})
+
+	When("the error is a wrapped network operation failure", func() {
+		It("should return true", func() {
+			Expect(resource.IsTransientErr(errors.Wrap(&url.Error{
+				Op:  "Get",
+				URL: "https://192.168.67.2:8443/api/v1/namespaces",
+				Err: &net.OpError{
+					Op:  "dial",
+					Net: "tcp",
+					Addr: &net.TCPAddr{
+						IP:   net.IP{192, 168, 67, 2},
+						Port: 8443,
+					},
+					Err: &net.DNSError{},
+				},
+			}, "wrapped"))).To(BeTrue())
+		})
+	})
+
+	When("the error is not transient", func() {
+		It("should return false", func() {
+			Expect(resource.IsTransientErr(apierrors.NewBadRequest(""))).To(BeFalse())
+		})
+	})
+
+	When("the error is nil", func() {
+		It("should return false", func() {
+			Expect(resource.IsTransientErr(nil)).To(BeFalse())
+		})
+	})
+})