fix(toolkit): do not deploy empty stacks

packages/aws-cdk/bin/cdk.ts

@@ -5,7 +5,7 @@ import colors = require('colors/safe');
 import path = require('path');
 import yargs = require('yargs');
 
-import { bootstrapEnvironment, BootstrapEnvironmentProps, destroyStack, SDK } from '../lib';
+import { bootstrapEnvironment, BootstrapEnvironmentProps, SDK } from '../lib';
 import { environmentsFromDescriptors, globEnvironmentsFromStacks } from '../lib/api/cxapp/environments';
 import { execProgram } from '../lib/api/cxapp/exec';
 import { AppStacks, DefaultSelection, ExtendedStackSelection } from '../lib/api/cxapp/stacks';
@@ -19,9 +19,6 @@ import { serializeStructure } from '../lib/serialize';
 import { Configuration, Settings } from '../lib/settings';
 import version = require('../lib/version');
 
-// tslint:disable-next-line:no-var-requires
-const promptly = require('promptly');
-
 // tslint:disable:no-shadowed-variable max-line-length
 async function parseCommandLineArguments() {
   const initTemplateLanuages = await availableInitLanguages;
@@ -201,11 +198,18 @@ async function initCommandLine() {
           requireApproval: configuration.settings.get(['requireApproval']),
           ci: args.ci,
           reuseAssets: args['build-exclude'],
-          tags: configuration.settings.get(['tags'])
+          tags: configuration.settings.get(['tags']),
+          sdk: aws,
         });
 
       case 'destroy':
-        return await cliDestroy(args.STACKS, args.exclusively, args.force, args.roleArn);
+        return await cli.destroy({
+          stackNames: args.STACKS,
+          exclusively: args.exclusively,
+          force: args.force,
+          roleArn: args.roleArn,
+          sdk: aws,
+        });
 
       case 'synthesize':
       case 'synth':
@@ -332,35 +336,6 @@ async function initCommandLine() {
     return 0; // exit-code
   }
 
-  async function cliDestroy(stackNames: string[], exclusively: boolean, force: boolean, roleArn: string | undefined) {
-    const stacks = await appStacks.selectStacks(stackNames, {
-      extend: exclusively ? ExtendedStackSelection.None : ExtendedStackSelection.Downstream,
-      defaultBehavior: DefaultSelection.OnlySingle
-    });
-
-    // The stacks will have been ordered for deployment, so reverse them for deletion.
-    stacks.reverse();
-
-    if (!force) {
-      // tslint:disable-next-line:max-line-length
-      const confirmed = await promptly.confirm(`Are you sure you want to delete: ${colors.blue(stacks.map(s => s.name).join(', '))} (y/n)?`);
-      if (!confirmed) {
-        return;
-      }
-    }
-
-    for (const stack of stacks) {
-      success('%s: destroying...', colors.blue(stack.name));
-      try {
-        await destroyStack({ stack, sdk: aws, deployName: stack.name, roleArn });
-        success('\n ✅  %s: destroyed', colors.blue(stack.name));
-      } catch (e) {
-        error('\n ❌  %s: destroy failed', colors.blue(stack.name), e);
-        throw e;
-      }
-    }
-  }
-
   /**
    * Match a single stack from the list of available stacks
    */

packages/aws-cdk/lib/cdk-toolkit.ts

@@ -1,10 +1,14 @@
 import colors = require('colors/safe');
 import fs = require('fs-extra');
 import { format } from 'util';
+import { Mode } from './api/aws-auth/credentials';
 import { AppStacks, DefaultSelection, ExtendedStackSelection, Tag } from "./api/cxapp/stacks";
+import { destroyStack } from './api/deploy-stack';
 import { IDeploymentTarget } from './api/deployment-target';
+import { stackExists } from './api/util/cloudformation';
+import { ISDK } from './api/util/sdk';
 import { printSecurityDiff, printStackDiff, RequireApproval } from './diff';
-import { data, error, highlight, print, success } from './logging';
+import { data, error, highlight, print, success, warning } from './logging';
 import { deserializeStructure } from './serialize';
 
 // tslint:disable-next-line:no-var-requires
@@ -90,6 +94,24 @@ export class CdkToolkit {
         throw new Error(`Stack ${stack.name} does not define an environment, and AWS credentials could not be obtained from standard locations or no region was configured.`);
       }
 
+      if (Object.keys(stack.template.Resources || {}).length === 0) { // The generated stack has no resources
+        const cfn = await options.sdk.cloudFormation(stack.environment.account, stack.environment.region, Mode.ForReading);
+        if (!await stackExists(cfn, stack.name)) {
+          warning('%s: stack has no resources, skipping deployment.', colors.bold(stack.name));
+        } else {
+          warning('%s: stack has no resources, deleting existing stack.', colors.bold(stack.name));
+          await this.destroy({
+            stackNames: [stack.name],
+            exclusively: true,
+            force: true,
+            roleArn: options.roleArn,
+            sdk: options.sdk,
+            fromDeploy: true,
+          });
+        }
+        continue;
+      }
+
       if (requireApproval !== RequireApproval.Never) {
         const currentTemplate = await this.provisioner.readCurrentTemplate(stack);
         if (printSecurityDiff(currentTemplate, stack, requireApproval)) {
@@ -152,6 +174,36 @@ export class CdkToolkit {
       }
     }
   }
+
+  public async destroy(options: DestroyOptions) {
+    const stacks = await this.appStacks.selectStacks(options.stackNames, {
+      extend: options.exclusively ? ExtendedStackSelection.None : ExtendedStackSelection.Downstream,
+      defaultBehavior: DefaultSelection.OnlySingle
+    });
+
+    // The stacks will have been ordered for deployment, so reverse them for deletion.
+    stacks.reverse();
+
+    if (!options.force) {
+      // tslint:disable-next-line:max-line-length
+      const confirmed = await promptly.confirm(`Are you sure you want to delete: ${colors.blue(stacks.map(s => s.name).join(', '))} (y/n)?`);
+      if (!confirmed) {
+        return;
+      }
+    }
+
+    const action = options.fromDeploy ? 'deploy' : 'destroy';
+    for (const stack of stacks) {
+      success('%s: destroying...', colors.blue(stack.name));
+      try {
+        await destroyStack({ stack, sdk: options.sdk, deployName: stack.name, roleArn: options.roleArn });
+        success(`\n ✅  %s: ${action}ed`, colors.blue(stack.name));
+      } catch (e) {
+        error(`\n ❌  %s: ${action} failed`, colors.blue(stack.name), e);
+        throw e;
+      }
+    }
+  }
 }
 
 export interface DiffOptions {
@@ -244,4 +296,41 @@ export interface DeployOptions {
    * Tags to pass to CloudFormation for deployment
    */
   tags?: Tag[];
+
+  /**
+   * AWS SDK
+   */
+  sdk: ISDK;
+}
+
+export interface DestroyOptions {
+  /**
+   * The names of the stacks to delete
+   */
+  stackNames: string[];
+
+  /**
+   * Whether to exclude stacks that depend on the stacks to be deleted
+   */
+  exclusively: boolean;
+
+  /**
+   * Whether to skip prompting for confirmation
+   */
+  force: boolean;
+
+  /**
+   * The arn of the IAM role to use
+   */
+  roleArn?: string;
+
+  /**
+   * AWS SDK
+   */
+  sdk: ISDK;
+
+  /**
+   * Whether the destroy request came from a deploy.
+   */
+  fromDeploy?: boolean
 }

packages/aws-cdk/test/integ/cli/app/app.js

@@ -124,6 +124,16 @@ class ImportVpcStack extends cdk.Stack {
   }
 }
 
+class ConditionalResourceStack extends cdk.Stack {
+  constructor(parent, id, props) {
+    super(parent, id, props);
+
+    if (!process.env.NO_RESOURCE) {
+      new iam.User(this, 'User');
+    }
+  }
+}
+
 const stackPrefix = process.env.STACK_NAME_PREFIX || 'cdk-toolkit-integration';
 
 const app = new cdk.App();
@@ -154,4 +164,6 @@ if (process.env.ENABLE_VPC_TESTING) { // Gating so we don't do context fetching
   new ImportVpcStack(app, `${stackPrefix}-import-vpc`, { env });
 }
 
+new ConditionalResourceStack(app, `${stackPrefix}-conditional-resource`)
+
 app.synth();

packages/aws-cdk/test/integ/cli/test-cdk-no-resource.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+set -euo pipefail
+scriptdir=$(cd $(dirname $0) && pwd)
+source ${scriptdir}/common.bash
+# ----------------------------------------------------------
+
+setup
+
+# Deploy without resource
+NO_RESOURCE="TRUE" cdk deploy ${STACK_NAME_PREFIX}-conditional-resource
+
+# Verify that deploy has been skipped
+deployed=1
+aws cloudformation describe-stacks --stack-name ${STACK_NAME_PREFIX}-conditional-resource > /dev/null 2>&1 || deployed=0
+
+if [ $deployed -ne 0 ]; then
+  fail 'Stack has been deployed'
+fi
+
+# Deploy the stack with resources
+cdk deploy ${STACK_NAME_PREFIX}-conditional-resource
+
+# Now, deploy the stack without resources
+NO_RESOURCE="TRUE" cdk deploy ${STACK_NAME_PREFIX}-conditional-resource
+
+# Verify that the stack has been destroyed
+destroyed=0
+aws cloudformation describe-stacks --stack-name ${STACK_NAME_PREFIX}-conditional-resource > /dev/null 2>&1 || destroyed=1
+
+if [ $destroyed -ne 1 ]; then
+  fail 'Stack has not been destroyed'
+fi
+

packages/aws-cdk/test/test.cdk-toolkit.ts

@@ -3,6 +3,7 @@ import nodeunit = require('nodeunit');
 import { AppStacks, Tag } from '../lib/api/cxapp/stacks';
 import { DeployStackResult } from '../lib/api/deploy-stack';
 import { DeployStackOptions, IDeploymentTarget, Template } from '../lib/api/deployment-target';
+import { SDK } from '../lib/api/util/sdk';
 import { CdkToolkit } from '../lib/cdk-toolkit';
 
 export = nodeunit.testCase({
@@ -19,7 +20,7 @@ export = nodeunit.testCase({
         });
 
         // WHEN
-        toolkit.deploy({ stackNames: ['Test-Stack-A', 'Test-Stack-B'] });
+        toolkit.deploy({ stackNames: ['Test-Stack-A', 'Test-Stack-B'], sdk: new SDK() });
 
         // THEN
         test.done();