kubeadm: special case context errors in GetConfigMapWithShortRetry

If some code is about to go over the context deadline,
"x/time/rate/rate.go" would return and untyped error with the string
"would exceed context deadline". If some code already exceeded
the deadline the error would be of type DeadlineExceeded.
Ignore such context errors and only store API and connectivity errors.

cmd/kubeadm/app/util/apiclient/idempotency.go

@@ -19,6 +19,7 @@ package apiclient
 import (
 	"context"
 	"encoding/json"
+	"strings"
 	"time"
 
 	"github.com/pkg/errors"
@@ -346,7 +347,13 @@ func GetConfigMapWithShortRetry(client clientset.Interface, namespace, name stri
 			if err == nil {
 				return true, nil
 			}
-			lastError = err
+			// If some code is about to go over the context deadline, "x/time/rate/rate.go" would return
+			// and untyped error with the string "would exceed context deadline". If some code already exceeded
+			// the deadline the error would be of type DeadlineExceeded. Ignore such context errors and only store
+			// API and connectivity errors.
+			if !strings.Contains(err.Error(), "would exceed context deadline") && !errors.Is(err, context.DeadlineExceeded) {
+				lastError = err
+			}
 			return false, nil
 		})
 	if err == nil {

cmd/kubeadm/app/util/apiclient/idempotency_test.go

@@ -237,3 +237,54 @@ func TestMutateConfigMapWithConflict(t *testing.T) {
 		t.Fatalf("ConfigMap mutation with conflict was invalid, has: %q", cm.Data["key"])
 	}
 }
+
+func TestGetConfigMapWithShortRetry(t *testing.T) {
+	testcases := []struct {
+		name           string
+		reactorFunc    func(core.Action) (bool, runtime.Object, error)
+		errorCheckFunc func(*testing.T, error)
+	}{
+		{
+			name: "context deadline exceeded error is handled",
+			reactorFunc: func(core.Action) (bool, runtime.Object, error) {
+				return true, nil, context.DeadlineExceeded
+			},
+			errorCheckFunc: func(t *testing.T, err error) {
+				if err != nil {
+					t.Errorf("unexpected error: %v", err)
+				}
+			},
+		},
+		{
+			name: "would exceed context deadline error is handled",
+			reactorFunc: func(core.Action) (bool, runtime.Object, error) {
+				return true, nil, errors.New("Wait returned an error: rate: Wait(n=1) would exceed context deadline")
+			},
+			errorCheckFunc: func(t *testing.T, err error) {
+				if err != nil {
+					t.Errorf("unexpected error: %v", err)
+				}
+			},
+		},
+		{
+			name: "API error is not handled",
+			reactorFunc: func(core.Action) (bool, runtime.Object, error) {
+				return true, nil, apierrors.NewNotFound(schema.GroupResource{}, "")
+			},
+			errorCheckFunc: func(t *testing.T, err error) {
+				if !apierrors.IsNotFound(err) {
+					t.Errorf("expected error: IsNotFound, got: %v", err)
+				}
+			},
+		},
+	}
+
+	for _, tc := range testcases {
+		t.Run(tc.name, func(t *testing.T) {
+			client := fake.NewSimpleClientset()
+			client.PrependReactor("get", "configmaps", tc.reactorFunc)
+			_, err := GetConfigMapWithShortRetry(client, "foo", "bar")
+			tc.errorCheckFunc(t, err)
+		})
+	}
+}