From e04fe9795980edaf3c9250db24968fdd00f33cb8 Mon Sep 17 00:00:00 2001
From: The Magician <magic-modules@google.com>
Date: Thu, 13 May 2021 12:07:53 -0700
Subject: [PATCH] allow api gateway to change (#4782) (#3248)

Signed-off-by: Modular Magician <magic-modules@google.com>
---
 .changelog/4782.txt                              |  3 +++
 google-beta/resource_api_gateway_gateway.go      | 14 ++++++++++++--
 google-beta/resource_api_gateway_gateway_test.go |  3 +++
 website/docs/r/api_gateway_gateway.html.markdown |  3 ++-
 4 files changed, 20 insertions(+), 3 deletions(-)
 create mode 100644 .changelog/4782.txt

diff --git a/.changelog/4782.txt b/.changelog/4782.txt
new file mode 100644
index 0000000000..52683a6419
--- /dev/null
+++ b/.changelog/4782.txt
@@ -0,0 +1,3 @@
+```release-note:enhancement
+apigateway: allowed field `apiconfig` to change on resource `google_apigateway_gateway`
+```
diff --git a/google-beta/resource_api_gateway_gateway.go b/google-beta/resource_api_gateway_gateway.go
index 982e7b70ee..e160fdbb22 100644
--- a/google-beta/resource_api_gateway_gateway.go
+++ b/google-beta/resource_api_gateway_gateway.go
@@ -45,9 +45,9 @@ func resourceApiGatewayGateway() *schema.Resource {
 			"api_config": {
 				Type:             schema.TypeString,
 				Required:         true,
-				ForceNew:         true,
 				DiffSuppressFunc: compareResourceNames,
-				Description:      `Resource name of the API Config for this Gateway. Format: projects/{project}/locations/global/apis/{api}/configs/{apiConfig}`,
+				Description: `Resource name of the API Config for this Gateway. Format: projects/{project}/locations/global/apis/{api}/configs/{apiConfig}.
+When changing api configs please ensure the new config is a new resource and the lifecycle rule 'create_before_destroy' is set.`,
 			},
 			"gateway_id": {
 				Type:        schema.TypeString,
@@ -256,6 +256,12 @@ func resourceApiGatewayGatewayUpdate(d *schema.ResourceData, meta interface{}) e
 	} else if v, ok := d.GetOkExists("display_name"); !isEmptyValue(reflect.ValueOf(v)) && (ok || !reflect.DeepEqual(v, displayNameProp)) {
 		obj["displayName"] = displayNameProp
 	}
+	apiConfigProp, err := expandApiGatewayGatewayApiConfig(d.Get("api_config"), d, config)
+	if err != nil {
+		return err
+	} else if v, ok := d.GetOkExists("api_config"); !isEmptyValue(reflect.ValueOf(v)) && (ok || !reflect.DeepEqual(v, apiConfigProp)) {
+		obj["apiConfig"] = apiConfigProp
+	}
 	labelsProp, err := expandApiGatewayGatewayLabels(d.Get("labels"), d, config)
 	if err != nil {
 		return err
@@ -275,6 +281,10 @@ func resourceApiGatewayGatewayUpdate(d *schema.ResourceData, meta interface{}) e
 		updateMask = append(updateMask, "displayName")
 	}
 
+	if d.HasChange("api_config") {
+		updateMask = append(updateMask, "apiConfig")
+	}
+
 	if d.HasChange("labels") {
 		updateMask = append(updateMask, "labels")
 	}
diff --git a/google-beta/resource_api_gateway_gateway_test.go b/google-beta/resource_api_gateway_gateway_test.go
index fb6584f15c..fa2cb747f1 100644
--- a/google-beta/resource_api_gateway_gateway_test.go
+++ b/google-beta/resource_api_gateway_gateway_test.go
@@ -39,6 +39,9 @@ resource "google_api_gateway_api_config" "api_gw" {
   provider = google-beta
   api = google_api_gateway_api.api_gw.api_id
   api_config_id = "tf-test-api-gw%{random_suffix}"
+	lifecycle {
+    create_before_destroy = true
+  }
 
   openapi_documents {
     document {
diff --git a/website/docs/r/api_gateway_gateway.html.markdown b/website/docs/r/api_gateway_gateway.html.markdown
index 6646e7bed8..e6058b93bd 100644
--- a/website/docs/r/api_gateway_gateway.html.markdown
+++ b/website/docs/r/api_gateway_gateway.html.markdown
@@ -77,7 +77,8 @@ The following arguments are supported:
 
 * `api_config` -
   (Required)
-  Resource name of the API Config for this Gateway. Format: projects/{project}/locations/global/apis/{api}/configs/{apiConfig}
+  Resource name of the API Config for this Gateway. Format: projects/{project}/locations/global/apis/{api}/configs/{apiConfig}.
+  When changing api configs please ensure the new config is a new resource and the lifecycle rule `create_before_destroy` is set.
 
 * `gateway_id` -
   (Required)