cli: allow any well formatted zone in iam create

cli/internal/cmd/iamcreate.go

@@ -402,18 +402,9 @@ func (c *awsIAMCreator) parseFlagsAndSetupConfig(cmd *cobra.Command, flags iamFl
 		zone:   zone,
 	}
 
-	if strings.HasPrefix(zone, "eu-central-1") {
+	flags.aws.region, err = awsZoneToRegion(zone)
-		flags.aws.region = "eu-central-1"
+	if err != nil {
-	} else if strings.HasPrefix(zone, "eu-west-1") {
+		return iamFlags{}, fmt.Errorf("invalid AWS zone. To find a valid zone, please refer to our docs and https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-regions-availability-zones.html#concepts-availability-zones")
-		flags.aws.region = "eu-west-1"
-	} else if strings.HasPrefix(zone, "eu-west-3") {
-		flags.aws.region = "eu-west-3"
-	} else if strings.HasPrefix(zone, "us-east-2") {
-		flags.aws.region = "us-east-2"
-	} else if strings.HasPrefix(zone, "ap-south-1") {
-		flags.aws.region = "ap-south-1"
-	} else {
-		return iamFlags{}, fmt.Errorf("invalid AWS region, to find a correct region please refer to our docs and https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-regions-availability-zones.html#concepts-availability-zones")
 	}
 
 	// Setup IAM config.
@@ -610,3 +601,17 @@ func parseIDFile(serviceAccountKeyBase64 string) (map[string]string, error) {
 	}
 	return out, nil
 }
+
+// awsZoneToRegion converts an AWS zone string to a region string.
+// Example: "us-east-1a" -> "us-east-1"
+// It does not check against a list of valid zones.
+// Instead, it just checks that the zone string is in the correct format:
+// "The code for Availability Zone is its Region code followed by a letter identifier."
+// https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-regions-availability-zones.html#concepts-availability-zones .
+func awsZoneToRegion(zone string) (string, error) {
+	parts := strings.Split(zone, "-")
+	if len(parts) < 3 || len(parts[2]) < 1 {
+		return "", fmt.Errorf("invalid zone string: %s", zone)
+	}
+	return fmt.Sprintf("%s-%s-%c", parts[0], parts[1], parts[2][0]), nil
+}

cli/internal/cmd/iamcreate_test.go

@@ -212,7 +212,7 @@ func TestIAMCreateAWS(t *testing.T) {
 			setupFs:    defaultFs,
 			creator:    &stubIAMCreator{id: validIAMIDFile},
 			provider:   cloudprovider.AWS,
-			zoneFlag:   "us-west-5b",
+			zoneFlag:   "us-west",
 			prefixFlag: "test",
 			yesFlag:    true,
 			wantErr:    true,