diff --git a/allowed-breaking-changes.txt b/allowed-breaking-changes.txt
index fd44c1df2ce34..d85b698a59ce6 100644
--- a/allowed-breaking-changes.txt
+++ b/allowed-breaking-changes.txt
@@ -19,3 +19,6 @@ removed:@aws-cdk/cdk-assets-schema.FileDestination
 removed:@aws-cdk/cdk-assets-schema.FileSource
 removed:@aws-cdk/cdk-assets-schema.ManifestFile
 removed:@aws-cdk/cdk-assets-schema.FileAssetPackaging
+
+changed-type:@aws-cdk/aws-codedeploy.IServerDeploymentGroup.autoScalingGroups
+changed-type:@aws-cdk/aws-codedeploy.ServerDeploymentGroup.autoScalingGroups
diff --git a/packages/@aws-cdk/aws-autoscaling/lib/auto-scaling-group.ts b/packages/@aws-cdk/aws-autoscaling/lib/auto-scaling-group.ts
index 157298b8e10b8..07aa86ff45306 100644
--- a/packages/@aws-cdk/aws-autoscaling/lib/auto-scaling-group.ts
+++ b/packages/@aws-cdk/aws-autoscaling/lib/auto-scaling-group.ts
@@ -390,7 +390,9 @@ abstract class AutoScalingGroupBase extends Resource implements IAutoScalingGrou
 
   public abstract autoScalingGroupName: string;
   public abstract autoScalingGroupArn: string;
+  public abstract readonly osType: ec2.OperatingSystemType;
   protected albTargetGroup?: elbv2.ApplicationTargetGroup;
+  public readonly grantPrincipal: iam.IPrincipal = new iam.UnknownPrincipal({ resource: this });
 
   /**
    * Send a message to either an SQS queue or SNS topic when instances launch or terminate
@@ -490,6 +492,10 @@ abstract class AutoScalingGroupBase extends Resource implements IAutoScalingGrou
   public scaleOnMetric(id: string, props: BasicStepScalingPolicyProps): StepScalingPolicy {
     return new StepScalingPolicy(this, id, { ...props, autoScalingGroup: this });
   }
+
+  public addUserData(..._commands: string[]): void {
+    // do nothing
+  }
 }
 
 /**
@@ -508,8 +514,7 @@ export class AutoScalingGroup extends AutoScalingGroupBase implements
   elb.ILoadBalancerTarget,
   ec2.IConnectable,
   elbv2.IApplicationLoadBalancerTarget,
-  elbv2.INetworkLoadBalancerTarget,
-  iam.IGrantable {
+  elbv2.INetworkLoadBalancerTarget {
 
   public static fromAutoScalingGroupName(scope: Construct, id: string, autoScalingGroupName: string): IAutoScalingGroup {
     class Import extends AutoScalingGroupBase {
@@ -519,6 +524,7 @@ export class AutoScalingGroup extends AutoScalingGroupBase implements
         resource: 'autoScalingGroup:*:autoScalingGroupName',
         resourceName: this.autoScalingGroupName,
       });
+      public readonly osType = ec2.OperatingSystemType.UNKNOWN;
     }
 
     return new Import(scope, id);
@@ -760,11 +766,7 @@ export class AutoScalingGroup extends AutoScalingGroupBase implements
     return { targetType: elbv2.TargetType.INSTANCE };
   }
 
-  /**
-   * Add command to the startup script of fleet instances.
-   * The command must be in the scripting language supported by the fleet's OS (i.e. Linux/Windows).
-   */
-  public addUserData(...commands: string[]) {
+  public addUserData(...commands: string[]): void {
     this.userData.addCommands(...commands);
   }
 
@@ -1121,7 +1123,7 @@ function validatePercentage(x?: number): number | undefined {
 /**
  * An AutoScalingGroup
  */
-export interface IAutoScalingGroup extends IResource {
+export interface IAutoScalingGroup extends IResource, iam.IGrantable {
   /**
    * The name of the AutoScalingGroup
    * @attribute
@@ -1134,6 +1136,19 @@ export interface IAutoScalingGroup extends IResource {
    */
   readonly autoScalingGroupArn: string;
 
+  /**
+   * The operating system family that the instances in this auto-scaling group belong to.
+   * Is 'UNKNOWN' for imported ASGs.
+   */
+  readonly osType: ec2.OperatingSystemType;
+
+  /**
+   * Add command to the startup script of fleet instances.
+   * The command must be in the scripting language supported by the fleet's OS (i.e. Linux/Windows).
+   * Does nothing for imported ASGs.
+   */
+  addUserData(...commands: string[]): void;
+
   /**
    * Send a message to either an SQS queue or SNS topic when instances launch or terminate
    */
diff --git a/packages/@aws-cdk/aws-codedeploy/lib/server/deployment-group.ts b/packages/@aws-cdk/aws-codedeploy/lib/server/deployment-group.ts
index 27f1b32fd3a46..3aa3f5915cded 100644
--- a/packages/@aws-cdk/aws-codedeploy/lib/server/deployment-group.ts
+++ b/packages/@aws-cdk/aws-codedeploy/lib/server/deployment-group.ts
@@ -24,7 +24,7 @@ export interface IServerDeploymentGroup extends cdk.IResource {
    */
   readonly deploymentGroupArn: string;
   readonly deploymentConfig: IServerDeploymentConfig;
-  readonly autoScalingGroups?: autoscaling.AutoScalingGroup[];
+  readonly autoScalingGroups?: autoscaling.IAutoScalingGroup[];
 }
 
 /**
@@ -69,7 +69,7 @@ abstract class ServerDeploymentGroupBase extends cdk.Resource implements IServer
   public abstract readonly deploymentGroupName: string;
   public abstract readonly deploymentGroupArn: string;
   public readonly deploymentConfig: IServerDeploymentConfig;
-  public abstract readonly autoScalingGroups?: autoscaling.AutoScalingGroup[];
+  public abstract readonly autoScalingGroups?: autoscaling.IAutoScalingGroup[];
 
   constructor(scope: cdk.Construct, id: string, deploymentConfig?: IServerDeploymentConfig, props?: cdk.ResourceProps) {
     super(scope, id, props);
@@ -171,7 +171,7 @@ export interface ServerDeploymentGroupProps {
    *
    * @default []
    */
-  readonly autoScalingGroups?: autoscaling.AutoScalingGroup[];
+  readonly autoScalingGroups?: autoscaling.IAutoScalingGroup[];
 
   /**
    * If you've provided any auto-scaling groups with the {@link #autoScalingGroups} property,
@@ -258,7 +258,7 @@ export class ServerDeploymentGroup extends ServerDeploymentGroupBase {
   public readonly deploymentGroupArn: string;
   public readonly deploymentGroupName: string;
 
-  private readonly _autoScalingGroups: autoscaling.AutoScalingGroup[];
+  private readonly _autoScalingGroups: autoscaling.IAutoScalingGroup[];
   private readonly installAgent: boolean;
   private readonly codeDeployBucket: s3.IBucket;
   private readonly alarms: cloudwatch.IAlarm[];
@@ -333,16 +333,16 @@ export class ServerDeploymentGroup extends ServerDeploymentGroupBase {
     this.alarms.push(alarm);
   }
 
-  public get autoScalingGroups(): autoscaling.AutoScalingGroup[] | undefined {
+  public get autoScalingGroups(): autoscaling.IAutoScalingGroup[] | undefined {
     return this._autoScalingGroups.slice();
   }
 
-  private addCodeDeployAgentInstallUserData(asg: autoscaling.AutoScalingGroup): void {
+  private addCodeDeployAgentInstallUserData(asg: autoscaling.IAutoScalingGroup): void {
     if (!this.installAgent) {
       return;
     }
 
-    this.codeDeployBucket.grantRead(asg.role, 'latest/*');
+    this.codeDeployBucket.grantRead(asg, 'latest/*');
 
     switch (asg.osType) {
       case ec2.OperatingSystemType.LINUX:
diff --git a/packages/@aws-cdk/aws-codepipeline-actions/lib/codedeploy/server-deploy-action.ts b/packages/@aws-cdk/aws-codepipeline-actions/lib/codedeploy/server-deploy-action.ts
index 98606a8aac9a1..07c0662824481 100644
--- a/packages/@aws-cdk/aws-codepipeline-actions/lib/codedeploy/server-deploy-action.ts
+++ b/packages/@aws-cdk/aws-codepipeline-actions/lib/codedeploy/server-deploy-action.ts
@@ -58,7 +58,7 @@ export class CodeDeployServerDeployAction extends Action {
 
     // grant the ASG Role permissions to read from the Pipeline Bucket
     for (const asg of this.deploymentGroup.autoScalingGroups || []) {
-      options.bucket.grantRead(asg.role);
+      options.bucket.grantRead(asg);
     }
 
     // the Action's Role needs to read from the Bucket to get artifacts
diff --git a/packages/@aws-cdk/aws-ec2/lib/machine-image.ts b/packages/@aws-cdk/aws-ec2/lib/machine-image.ts
index c00326888faf8..77834eecac7c1 100644
--- a/packages/@aws-cdk/aws-ec2/lib/machine-image.ts
+++ b/packages/@aws-cdk/aws-ec2/lib/machine-image.ts
@@ -411,6 +411,11 @@ export class GenericWindowsImage implements IMachineImage  {
 export enum OperatingSystemType {
   LINUX,
   WINDOWS,
+  /**
+   * Used when the type of the operating system is not known
+   * (for example, for imported Auto-Scaling Groups).
+   */
+  UNKNOWN,
 }
 
 /**
diff --git a/packages/@aws-cdk/aws-ec2/lib/user-data.ts b/packages/@aws-cdk/aws-ec2/lib/user-data.ts
index d82754f9e17a8..617563e6cd05a 100644
--- a/packages/@aws-cdk/aws-ec2/lib/user-data.ts
+++ b/packages/@aws-cdk/aws-ec2/lib/user-data.ts
@@ -89,6 +89,7 @@ export abstract class UserData {
     switch (os) {
       case OperatingSystemType.LINUX: return UserData.forLinux();
       case OperatingSystemType.WINDOWS: return UserData.forWindows();
+      case OperatingSystemType.UNKNOWN: throw new Error('Cannot determine UserData for unknown operating system type');
     }
   }
 
@@ -275,4 +276,4 @@ class CustomUserData extends UserData {
   public addSignalOnExitCommand(): void {
     throw new Error('CustomUserData does not support addSignalOnExitCommand, use UserData.forLinux() or UserData.forWindows() instead.');
   }
-}
\ No newline at end of file
+}