diff --git a/readme.az.common.md b/readme.az.common.md
index 29f0e9744..7a6527ce6 100644
--- a/readme.az.common.md
+++ b/readme.az.common.md
@@ -2,6 +2,8 @@
  
 ``` yaml $(az)
 extension-mode: experimental
+# customize library used in extension. azure.cli.core by default
+# cli-core-lib: azure.cli.core
  
 cli:
     naming:
diff --git a/src/plugins/azgenerator/Generator.ts b/src/plugins/azgenerator/Generator.ts
index 7f5ff49bd..612031866 100644
--- a/src/plugins/azgenerator/Generator.ts
+++ b/src/plugins/azgenerator/Generator.ts
@@ -25,7 +25,7 @@ import { GenerateNamespaceInit } from "./TemplateAzureCliNamespaceInit"
 import { GenerateAzureCliTestInit } from "./TemplateAzureCliTestInit"
 
 export async function GenerateAll(model: CodeModelAz,
-    generateReport: any, debug: boolean) {
+    generateReport: any, debug: boolean, cliCoreLib: string) {
     let files: any = {};
 
     await model.init();
@@ -37,10 +37,10 @@ export async function GenerateAll(model: CodeModelAz,
             let pathTop = "";
             let path = "azext_" + model.Extension_NameUnderscored + "/";
             
-            files[path + "generated/_params.py"] = GenerateAzureCliParams(model, debug);
-            files[path + "generated/commands.py"] = GenerateAzureCliCommands(model);
-            files[path + "generated/custom.py"] = GenerateAzureCliCustom(model);
-            files[path + "generated/_client_factory.py"] = GenerateAzureCliClientFactory(model);
+            files[path + "generated/_params.py"] = GenerateAzureCliParams(model, debug, cliCoreLib);
+            files[path + "generated/commands.py"] = GenerateAzureCliCommands(model, cliCoreLib);
+            files[path + "generated/custom.py"] = GenerateAzureCliCustom(model, cliCoreLib);
+            files[path + "generated/_client_factory.py"] = GenerateAzureCliClientFactory(model, cliCoreLib);
             files[path + "generated/_validators.py"] = GenerateAzureCliValidators(model);
             files[path + "generated/action.py"] = GenerateAzureCliActions(model);
             files[path + "generated/_help.py"] = GenerateAzureCliHelp(model, debug);
@@ -54,7 +54,7 @@ export async function GenerateAll(model: CodeModelAz,
             files[path + "manual/__init__.py"] = GenerateNamespaceInit(model);  
             files[path + "action.py"] = GenerateTopLevelImport(model, "action");  
             files[path + "custom.py"] = GenerateTopLevelImport(model, "custom");  
-            files[path + "__init__.py"] = GenerateAzureCliInit(model);
+            files[path + "__init__.py"] = GenerateAzureCliInit(model, cliCoreLib);
             files[pathTop + "HISTORY.rst"] = GenerateAzureCliHistory(model);
             files[pathTop + "README.md"] = GenerateAzureCliReadme(model);
             files[pathTop + "setup.cfg"] = GenerateAzureCliSetupCfg(model);
diff --git a/src/plugins/azgenerator/TemplateAzureCliClientFactory.ts b/src/plugins/azgenerator/TemplateAzureCliClientFactory.ts
index 0d6d01e31..04466c696 100644
--- a/src/plugins/azgenerator/TemplateAzureCliClientFactory.ts
+++ b/src/plugins/azgenerator/TemplateAzureCliClientFactory.ts
@@ -7,14 +7,14 @@ import { CodeModelAz } from "./CodeModelAz"
 import { HeaderGenerator } from "./Header";
 import { isNullOrUndefined } from "util";
 
-export function GenerateAzureCliClientFactory(model: CodeModelAz): string[] {
+export function GenerateAzureCliClientFactory(model: CodeModelAz, cliCoreLib: string): string[] {
     let header: HeaderGenerator = new HeaderGenerator();
     var output: string[] = header.getLines();
     model.SelectFirstCommandGroup();
     output.push("");
     output.push("");
     output.push("def cf_" + model.Extension_NameUnderscored + "_cl(cli_ctx, *_):");
-    output.push("    from azure.cli.core.commands.client_factory import get_mgmt_service_client");
+    output.push("    from " + cliCoreLib + ".commands.client_factory import get_mgmt_service_client");
     output.push("    from ..vendored_sdks." + model.PythonOperationsName + " import " + model.PythonMgmtClient);
 
     if (!isNullOrUndefined(model.Extension_ClientAuthenticationPolicy)) {
diff --git a/src/plugins/azgenerator/TemplateAzureCliCommands.ts b/src/plugins/azgenerator/TemplateAzureCliCommands.ts
index 6ecad3865..6ec32def3 100644
--- a/src/plugins/azgenerator/TemplateAzureCliCommands.ts
+++ b/src/plugins/azgenerator/TemplateAzureCliCommands.ts
@@ -10,13 +10,13 @@ import { isNullOrUndefined } from "util";
 import { SchemaType } from "@azure-tools/codemodel";
 
 let showCommandFunctionName = undefined;
-export function GenerateAzureCliCommands(model: CodeModelAz): string[] {
+export function GenerateAzureCliCommands(model: CodeModelAz, cliCoreLib: string): string[] {
     let header: HeaderGenerator = new HeaderGenerator();
 
     // this can't be currently reproduced
     header.disableTooManyStatements = true;
     header.disableTooManyLocals = true;
-    header.addFromImport("azure.cli.core.commands", ["CliCommandType"]);
+    header.addFromImport(cliCoreLib + ".commands", ["CliCommandType"]);
 
     let output: string[] = []
     output.push("");
diff --git a/src/plugins/azgenerator/TemplateAzureCliCustom.ts b/src/plugins/azgenerator/TemplateAzureCliCustom.ts
index 84856e449..fe4f6f413 100644
--- a/src/plugins/azgenerator/TemplateAzureCliCustom.ts
+++ b/src/plugins/azgenerator/TemplateAzureCliCustom.ts
@@ -9,7 +9,7 @@ import { Capitalize, ToCamelCase, ToMultiLine, ToPythonString } from '../../util
 import { CodeModelAz } from "./CodeModelAz";
 import { HeaderGenerator } from "./Header";
 
-export function GenerateAzureCliCustom(model: CodeModelAz): string[] {
+export function GenerateAzureCliCustom(model: CodeModelAz, cliCoreLib: string): string[] {
     let header: HeaderGenerator = new HeaderGenerator();
     header.disableTooManyLines = true;
 
@@ -29,7 +29,7 @@ export function GenerateAzureCliCustom(model: CodeModelAz): string[] {
     }
 
     if(required['nowait']) {
-        header.addFromImport("azure.cli.core.util", ["sdk_no_wait"]);
+        header.addFromImport(cliCoreLib + ".util", ["sdk_no_wait"]);
     }
 
     if(required['disableUnusedArgument']) {
diff --git a/src/plugins/azgenerator/TemplateAzureCliInit.ts b/src/plugins/azgenerator/TemplateAzureCliInit.ts
index f30490cf1..e05924ea0 100644
--- a/src/plugins/azgenerator/TemplateAzureCliInit.ts
+++ b/src/plugins/azgenerator/TemplateAzureCliInit.ts
@@ -7,9 +7,9 @@ import { CodeModelAz } from "./CodeModelAz"
 import { HeaderGenerator } from "./Header";
 import { ToMultiLine } from "../../utils/helper"
 
-export function GenerateAzureCliInit(model: CodeModelAz): string[] {
+export function GenerateAzureCliInit(model: CodeModelAz, cliCoreLib: string): string[] {
     let header: HeaderGenerator = new HeaderGenerator();
-    header.addFromImport("azure.cli.core", ["AzCommandsLoader"]);
+    header.addFromImport(cliCoreLib, ["AzCommandsLoader"]);
     var output: string[] = header.getLines();
 
     output.push("from azext_" + model.Extension_NameUnderscored + ".generated._help import helps  # pylint: disable=unused-import");
@@ -22,7 +22,7 @@ export function GenerateAzureCliInit(model: CodeModelAz): string[] {
     output.push("class " + model.Extension_NameClass + "CommandsLoader(AzCommandsLoader):");
     output.push("");
     output.push("    def __init__(self, cli_ctx=None):");
-    output.push("        from azure.cli.core.commands import CliCommandType");
+    output.push("        from " + cliCoreLib + ".commands import CliCommandType");
     output.push("        from azext_" + model.Extension_NameUnderscored + ".generated._client_factory import cf_" + model.Extension_NameUnderscored + "_cl");
     output.push("        " + model.Extension_NameUnderscored + "_custom = CliCommandType(");
     output.push("            operations_tmpl='azext_" + model.Extension_NameUnderscored + ".custom#{}',");
diff --git a/src/plugins/azgenerator/TemplateAzureCliParams.ts b/src/plugins/azgenerator/TemplateAzureCliParams.ts
index 208111bab..49b54bb1b 100644
--- a/src/plugins/azgenerator/TemplateAzureCliParams.ts
+++ b/src/plugins/azgenerator/TemplateAzureCliParams.ts
@@ -20,7 +20,7 @@ let hasLocationValidator = false;
 let hasTags = false;
 let actions: string[] = [];
 
-export function GenerateAzureCliParams(model: CodeModelAz, debug: boolean): string[] {
+export function GenerateAzureCliParams(model: CodeModelAz, debug: boolean, cliCoreLib: string): string[] {
     var output_args: string[] = [];
 
     output_args.push("");
@@ -65,7 +65,7 @@ export function GenerateAzureCliParams(model: CodeModelAz, debug: boolean): stri
     if (hasResourceGroup) parameterImports.push("resource_group_name_type");
     if (hasLocation) parameterImports.push("get_location_type");
 
-    header.addFromImport("azure.cli.core.commands.parameters", parameterImports);
+    header.addFromImport(cliCoreLib + ".commands.parameters", parameterImports);
     let validatorImports: string[] = [];
     if (hasLocationValidator) {
         validatorImports.push("get_default_location_from_resource_group");
@@ -74,7 +74,7 @@ export function GenerateAzureCliParams(model: CodeModelAz, debug: boolean): stri
         validatorImports.push("validate_file_or_dict");
     }
     if (validatorImports.length > 0) {
-        header.addFromImport('azure.cli.core.commands.validators', validatorImports);
+        header.addFromImport(cliCoreLib + '.commands.validators', validatorImports);
     }
 
     if (hasActions) {
diff --git a/src/plugins/azgenerator/azgenerator.ts b/src/plugins/azgenerator/azgenerator.ts
index 83ba52604..4a3f1095d 100644
--- a/src/plugins/azgenerator/azgenerator.ts
+++ b/src/plugins/azgenerator/azgenerator.ts
@@ -9,9 +9,10 @@ export async function processRequest(host: Host) {
     const debug = await host.GetValue('debug') || false;
     //host.Message({Channel:Channel.Warning, Text:"in azgenerator processRequest"});
     try {
+        const cliCoreLib = await host.GetValue('cli-core-lib') || 'azure.cli.core';
         const session = await startSession<CodeModel>(host, {}, codeModelSchema);
         let model = new CodeModelCliImpl(session);
-        let files: any = await GenerateAll(model, true, debug);
+        let files: any = await GenerateAll(model, true, debug, cliCoreLib);
         if (model.SelectFirstExtension()) {
             do {
                 let path = "azext_" + model.Extension_Name.replace("-", "_") + "/";