Extend AWS azToRegion method to support Local Zones and other partitions

staging/src/k8s.io/legacy-cloud-providers/aws/aws.go

@@ -25,6 +25,7 @@ import (
 	"io"
 	"net"
 	"path"
+	"regexp"
 	"sort"
 	"strconv"
 	"strings"
@@ -1202,7 +1203,13 @@ func azToRegion(az string) (string, error) {
 	if len(az) < 1 {
 		return "", fmt.Errorf("invalid (empty) AZ")
 	}
-	region := az[:len(az)-1]
+
+	r := regexp.MustCompile(`^([a-zA-Z]+-)+\d+`)
+	region := r.FindString(az)
+	if region == "" {
+		return "", fmt.Errorf("invalid AZ: %s", az)
+	}
+
 	return region, nil
 }
 

staging/src/k8s.io/legacy-cloud-providers/aws/aws_test.go

@@ -1982,3 +1982,23 @@ func newMockedFakeAWSServices(id string) *FakeAWSServices {
 	s.elb = &MockedFakeELB{FakeELB: s.elb.(*FakeELB)}
 	return s
 }
+
+func TestAzToRegion(t *testing.T) {
+	testCases := []struct {
+		az     string
+		region string
+	}{
+		{"us-west-2a", "us-west-2"},
+		{"us-west-2-lax-1a", "us-west-2"},
+		{"ap-northeast-2a", "ap-northeast-2"},
+		{"us-gov-east-1a", "us-gov-east-1"},
+		{"us-iso-east-1a", "us-iso-east-1"},
+		{"us-isob-east-1a", "us-isob-east-1"},
+	}
+
+	for _, testCase := range testCases {
+		result, err := azToRegion(testCase.az)
+		assert.NoError(t, err)
+		assert.Equal(t, testCase.region, result)
+	}
+}