compute/backend_service: Remove TTLs when using cache mode USE_ORIGIN_HEADERS

mmv1/templates/terraform/encoders/backend_service.go.erb

@@ -47,4 +47,43 @@ for _, backendRaw := range backends {
 	}
 }
 
+// This custom encoding helps prevent sending 0 for clientTtl, defaultTtl and
+// maxTtl in API calls to update these values  when unset in the provider
+// (doing so results in an API level error)
+c, cdnPolicyOk := d.GetOk("cdn_policy")
+
+// Only apply during updates
+if !cdnPolicyOk || obj["cdnPolicy"] == nil {
+	return obj, nil
+}
+
+currentCdnPolicies := c.([]interface{})
+
+// state does not contain cdnPolicy, so we can return early here as well
+if len(currentCdnPolicies) == 0 {
+	return obj, nil
+}
+
+futureCdnPolicy := obj["cdnPolicy"].(map[string]interface{})
+currentCdnPolicy := currentCdnPolicies[0].(map[string]interface{})
+
+cacheMode, ok := futureCdnPolicy["cache_mode"].(string)
+// Fallback to state if doesn't exist in object
+if !ok {
+	cacheMode = currentCdnPolicy["cache_mode"].(string)
+}
+
+switch cacheMode {
+case "USE_ORIGIN_HEADERS":
+	if _, ok := futureCdnPolicy["clientTtl"]; ok {
+		delete(futureCdnPolicy, "clientTtl")
+	}
+	if _, ok := futureCdnPolicy["defaultTtl"]; ok {
+		delete(futureCdnPolicy, "defaultTtl")
+	}
+	if _, ok := futureCdnPolicy["maxTtl"]; ok {
+		delete(futureCdnPolicy, "maxTtl")
+	}
+}
+
 return obj, nil

mmv1/third_party/terraform/services/compute/resource_compute_backend_service_test.go.erb

@@ -257,7 +257,6 @@ func TestAccComputeBackendService_withHttpsHealthCheck(t *testing.T) {
 	})
 }
 
-<% unless version == 'ga' -%>
 func TestAccComputeBackendService_withCdnPolicy(t *testing.T) {
 	t.Parallel()
 
@@ -301,10 +300,17 @@ func TestAccComputeBackendService_withCdnPolicy(t *testing.T) {
 				ImportState:       true,
 				ImportStateVerify: true,
 			},
+			{
+				Config: testAccComputeBackendService_withCdnPolicyUseOriginHeaders(serviceName, checkName),
+			},
+			{
+				ResourceName:      "google_compute_backend_service.foobar",
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
 		},
 	})
 }
-<% end -%>
 
 func TestAccComputeBackendService_withSecurityPolicy(t *testing.T) {
 	t.Parallel()
@@ -1373,7 +1379,6 @@ resource "google_compute_https_health_check" "zero" {
 `, serviceName, checkName)
 }
 
-<% unless version == 'ga' -%>
 func testAccComputeBackendService_withCdnPolicy(serviceName, checkName string) string {
 	return fmt.Sprintf(`
 resource "google_compute_backend_service" "foobar" {
@@ -1456,7 +1461,30 @@ resource "google_compute_http_health_check" "zero" {
 `, serviceName, headerName, checkName)
 }
 
-<% end -%>
+func testAccComputeBackendService_withCdnPolicyUseOriginHeaders(serviceName, checkName string) string {
+	return fmt.Sprintf(`
+resource "google_compute_backend_service" "foobar" {
+  name          = "%s"
+  health_checks = [google_compute_http_health_check.zero.self_link]
+
+  cdn_policy {
+    cache_mode = "USE_ORIGIN_HEADERS"
+    cache_key_policy {
+      include_protocol       = true
+      include_host           = true
+      include_query_string   = true
+    }
+  }
+}
+
+resource "google_compute_http_health_check" "zero" {
+  name               = "%s"
+  request_path       = "/"
+  check_interval_sec = 1
+  timeout_sec        = 1
+}
+`, serviceName, checkName)
+}
 
 func testAccComputeBackendService_withSecurityPolicy(serviceName, checkName, polName, edgePolName, polLink string, edgePolLink string) string {
 	return fmt.Sprintf(`