external name: added common external name configurations

Signed-off-by: Muvaffak Onus <me@muvaf.com>

pkg/config/common.go

@@ -0,0 +1,40 @@
+/*
+Copyright 2021 The Crossplane Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package config
+
+// Common ExternalName configurations.
+var (
+	// NameFromExternalName uses "name" field in the attributes as the external
+	// name of the resource.
+	NameFromExternalName = ExternalName{
+		SetNameAttributeFn: func(base map[string]interface{}, name string) {
+			base["name"] = name
+		},
+		OmittedFields: []string{
+			"name",
+			"name_prefix",
+		},
+	}
+
+	// NameFromProvider is used in resources whose identifier is assigned by
+	// the remote client, such as AWS VPC where it gets an identifier like
+	// vpc-2213das instead of letting user choose a name.
+	NameFromProvider = ExternalName{
+		SetNameAttributeFn:     NopSetNameAttribute,
+		DisableNameInitializer: true,
+	}
+)