aws · rix0rrr · Jun 29, 2020 · Jun 30, 2020 · Jun 30, 2020 · Jun 30, 2020
diff --git a/packages/@aws-cdk/assert/lib/assertions/have-resource.ts b/packages/@aws-cdk/assert/lib/assertions/have-resource.ts
@@ -160,4 +160,4 @@ export function isSuperObject(superObj: any, pattern: any, errors: string[] = []
     errors.push(inspection.failureReason);
   }
   return ret;
-}
+}
diff --git a/packages/@aws-cdk/aws-autoscaling/README.md b/packages/@aws-cdk/aws-autoscaling/README.md
@@ -1,4 +1,5 @@
 ## Amazon EC2 Auto Scaling Construct Library
+
 <!--BEGIN STABILITY BANNER-->
 ---
 
@@ -11,8 +12,6 @@
 
 This module is part of the [AWS Cloud Development Kit](https://github.com/aws/aws-cdk) project.
 
-### Fleet
-
 ### Auto Scaling Group
 
 An `AutoScalingGroup` represents a number of instances on which you run your code. You
@@ -224,6 +223,39 @@ autoScalingGroup.scaleOnSchedule('AllowDownscalingAtNight', {
 });
 ```
 
+### Configuring Instances using CloudFormation Init
+
+It is possible to use the CloudFormation Init mechanism to configure the
+instances in the AutoScalingGroup. You can write files to it, run commands,
+start services, etc. See the documentation of
+[AWS::CloudFormation::Init](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-init.html)
+and the documentation of CDK's `aws-ec2` library for more information.
+
+When you specify a CloudFormation Init configuration for an AutoScalingGroup:
+
+* you *must* also specify `signals` to configure how long CloudFormation
+  should wait for the instances to successfully configure themselves.
+* you *should* also specify an `updatePolicy` to configure how instances
+  should be updated when the AutoScalingGroup is updated (for example,
+  when the AMI is updated).
+
+Here's an example of using CloudFormation Init to write a file to the
+instance hosts on startup:
+
+```ts
+new autoscaling.AutoScalingGroup(this, 'ASG', {
+  // ...
+
+  init: ec2.CloudFormationInit.fromElements(
+    ec2.InitFile.fromString('/etc/my_instance', 'This got written during instance startup'),
+  ),
+  signals: autoscaling.Signals.waitForAll({
+    timeout: Duration.minutes(10),
+  }),
+  updatePolicy: autoscaling.UpdatePolicy.rollingUpdate(),
+});
+```
+
 ### Allowing Connections
 
 See the documentation of the `@aws-cdk/aws-ec2` package for more information
@@ -241,7 +273,6 @@ To disable detailed instance monitoring, specify `instanceMonitoring` property
 for the `AutoscalingGroup` resource as `Monitoring.BASIC`. Otherwise detailed monitoring
 will be enabled.
 
-
 ### Future work
 
 - [ ] CloudWatch Events (impossible to add currently as the AutoScalingGroup ARN is
-Original file line number
+Diff line change
@@ Expand Up @@
         errors.push(inspection.failureReason);
       }
       return ret;
-    }
+    }