Add Gateway DNS forwarder datasource

This solution adds a data source for Gateway DNS forwarder,
to get DNS forwarders IP if it is created in a different project.

Fixes #821.

Signed-off-by: Qiyue Yao <[email protected]>

nsxt/data_source_nsxt_policy_gateway_dns_forwarder.go

@@ -0,0 +1,40 @@
+/* Copyright © 2023 VMware, Inc. All Rights Reserved.
+   SPDX-License-Identifier: MPL-2.0 */
+
+package nsxt
+
+import (
+	"fmt"
+
+	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
+)
+
+func dataSourceNsxtPolicyGatewayDNSForwarder() *schema.Resource {
+	return &schema.Resource{
+		Read: dataSourceNsxtPolicyGatewayDNSForwarderRead,
+
+		Schema: map[string]*schema.Schema{
+			"id":           getDataSourceIDSchema(),
+			"display_name": getDataSourceDisplayNameSchema(),
+			"description":  getDataSourceDescriptionSchema(),
+			"path":         getPathSchema(),
+			"gateway_path": getPolicyPathSchema(false, false, "Gateway path"),
+			"context":      getContextSchema(),
+		},
+	}
+}
+
+func dataSourceNsxtPolicyGatewayDNSForwarderRead(d *schema.ResourceData, m interface{}) error {
+	connector := getPolicyConnector(m)
+
+	gwPath := d.Get("gateway_path").(string)
+	query := make(map[string]string)
+	if len(gwPath) > 0 {
+		query["parent_path"] = fmt.Sprintf("%s*", gwPath)
+	}
+	_, err := policyDataSourceResourceReadWithValidation(d, connector, getSessionContext(d, m), "PolicyDnsForwarder", query, false)
+	if err != nil {
+		return err
+	}
+	return nil
+}

nsxt/provider.go

@@ -283,6 +283,7 @@ func Provider() *schema.Provider {
 			"nsxt_policy_l2_vpn_service":              dataSourceNsxtPolicyL2VpnService(),
 			"nsxt_policy_segment":                     dataSourceNsxtPolicySegment(),
 			"nsxt_policy_project":                     dataSourceNsxtPolicyProject(),
+			"nsxt_policy_gateway_dns_forwarder":       dataSourceNsxtPolicyGatewayDNSForwarder(),
 			"nsxt_policy_gateway_prefix_list":         dataSourceNsxtPolicyGatewayPrefixList(),
 			"nsxt_policy_gateway_route_map":           dataSourceNsxtPolicyGatewayRouteMap(),
 			"nsxt_policy_uplink_host_switch_profile":  dataSourceNsxtUplinkHostSwitchProfile(),

nsxt/resource_nsxt_policy_gateway_dns_forwarder_test.go

@@ -261,7 +261,14 @@ resource "nsxt_policy_gateway_dns_forwarder" "test" {
     tag   = "tag1"
   }
 }
-`, context, attrMap["display_name"], attrMap["description"], whyDoesGoNeedToBeSoComplicated[isT0], attrMap["listener_ip"], attrMap["enabled"], attrMap["log_level"], attrMap["cache_size"])
+
+data "nsxt_policy_gateway_dns_forwarder" "test" {
+  display_name = "%s"
+
+  gateway_path = nsxt_policy_tier%d_gateway.test.path
+  depends_on = [nsxt_policy_gateway_dns_forwarder.test]
+}
+`, context, attrMap["display_name"], attrMap["description"], whyDoesGoNeedToBeSoComplicated[isT0], attrMap["listener_ip"], attrMap["enabled"], attrMap["log_level"], attrMap["cache_size"], attrMap["display_name"], whyDoesGoNeedToBeSoComplicated[isT0])
 }
 
 func testAccNsxtPolicyGatewayDNSForwarderMinimalistic(isT0, withContext bool) string {

website/docs/d/policy_gateway_dns_forwarder.html.markdown

@@ -0,0 +1,36 @@
+---
+subcategory: "DNS"
+layout: "nsxt"
+page_title: "NSXT: policy_gateway_dns_forwarder"
+description: A policy gateway DNS forwarder data source.
+---
+
+# nsxt_policy_gateway_dns_forwarder
+
+This data source provides information about policy gateways DNS forwarder.
+
+This data source is applicable to NSX Policy Manager, NSX Global Manager and VMC.
+
+## Example Usage
+
+```hcl
+data "nsxt_policy_gateway_dns_forwarder" "my_dns_forwarder" {
+  display_name = "dns-forwarder1"
+  gateway_path = data.nsxt_policy_tier1_gateway.path
+}
+```
+
+## Argument Reference
+
+* `gateway_path` - (Required) Path for the gateway.
+* `id` - (Optional) The ID of gateway DNS forwarder to retrieve.
+* `display_name` - (Optional) The Display Name of the gateway DNS forwarder to retrieve.
+* `context` - (Optional) The context which the object belongs to
+  * `project_id` - (Required) The ID of the project which the object belongs to
+
+## Attributes Reference
+
+In addition to arguments listed above, the following attributes are exported:
+
+* `description` - The description of the resource.
+* `path` - The NSX path of the policy resource.