feat(lambda): autoscaling for lambda aliases

packages/@aws-cdk/aws-lambda/lib/alias.ts

@@ -1,9 +1,12 @@
+import * as appscaling from '@aws-cdk/aws-applicationautoscaling';
 import * as cloudwatch from '@aws-cdk/aws-cloudwatch';
-import { Construct } from '@aws-cdk/core';
+import * as iam from '@aws-cdk/aws-iam';
+import { Construct, Stack} from '@aws-cdk/core';
 import { EventInvokeConfigOptions } from './event-invoke-config';
 import { IFunction, QualifiedFunctionBase } from './function-base';
 import { extractQualifierFromArn, IVersion } from './lambda-version';
 import { CfnAlias } from './lambda.generated';
+import { EnableScalingProps, IScalableVersionAttribute, ScalableVersionAttribute } from './scalable-version-attribute';
 
 export interface IAlias extends IFunction {
   /**
@@ -129,6 +132,9 @@ export class Alias extends QualifiedFunctionBase implements IAlias {
 
   protected readonly canCreatePermissions: boolean = true;
 
+  private provisionedConcurrency: boolean;
+  private scalableAlias?: ScalableVersionAttribute;
+
   constructor(scope: Construct, id: string, props: AliasProps) {
     super(scope, id, {
       physicalName: props.aliasName,
@@ -147,6 +153,8 @@ export class Alias extends QualifiedFunctionBase implements IAlias {
       provisionedConcurrencyConfig: this.determineProvisionedConcurrency(props),
     });
 
+    this.provisionedConcurrency = props.provisionedConcurrentExecutions ? true : false;
+
     this.functionArn = this.getResourceArnAttribute(alias.ref, {
       service: 'lambda',
       resource: 'function',
@@ -193,6 +201,39 @@ export class Alias extends QualifiedFunctionBase implements IAlias {
     });
   }
 
+  /**
+   * Enable autoscaling for the given lambda version. Requires that lambda version has provisioned concurrency.
+   * @param props The properties for autoscaling
+   */
+  public autoScaleProvisionedConcurrency(props: EnableScalingProps): IScalableVersionAttribute {
+    if (!this.provisionedConcurrency) {
+      throw new Error('Autoscaling is available for aliases with provisioned concurrency only');
+    }
+    if (this.scalableAlias) {
+      throw new Error('Autoscaling already enabled for this alias');
+    }
+    // Use a Service Linked Role
+    // https://docs.aws.amazon.com/autoscaling/application/userguide/application-auto-scaling-service-linked-roles.html
+    const role = iam.Role.fromRoleArn(this, 'ScalingRole', Stack.of(this).formatArn({
+      service: 'iam',
+      region: '',
+      resource: 'role/aws-service-role/lambda.application-autoscaling.amazonaws.com',
+      resourceName: 'AWSServiceRoleForApplicationAutoScaling_LambdaConcurrency',
+    }));
+
+    this.scalableAlias = new ScalableVersionAttribute(this, 'VersionScaling', {
+      serviceNamespace: appscaling.ServiceNamespace.LAMBDA,
+      dimension: 'lambda:function:ProvisionedConcurrency',
+      minCapacity: props.minCapacity,
+      maxCapacity: props.maxCapacity,
+      resourceId: `function:${this.lambda.functionName}:${this.aliasName}`,
+      role,
+    });
+
+    // Make sure that alias is created before the autoscale resources
+    this.scalableAlias.node.addDependency(this);
+  }
+
   /**
    * Calculate the routingConfig parameter from the input props
    */

packages/@aws-cdk/aws-lambda/lib/index.ts

@@ -12,6 +12,7 @@ export * from './event-source';
 export * from './event-source-mapping';
 export * from './destination';
 export * from './event-invoke-config';
+export * from './scalable-version-attribute';
 
 export * from './log-retention';
 

packages/@aws-cdk/aws-lambda/lib/lambda-version.ts

@@ -1,10 +1,13 @@
+import * as appscaling from '@aws-cdk/aws-applicationautoscaling';
 import * as cloudwatch from '@aws-cdk/aws-cloudwatch';
-import { Construct, Fn, RemovalPolicy } from '@aws-cdk/core';
+import * as iam from '@aws-cdk/aws-iam';
+import { Construct, Fn, RemovalPolicy, Stack } from '@aws-cdk/core';
 import { Alias, AliasOptions } from './alias';
 import { EventInvokeConfigOptions } from './event-invoke-config';
 import { Function } from './function';
 import { IFunction, QualifiedFunctionBase } from './function-base';
 import { CfnVersion } from './lambda.generated';
+import { EnableScalingProps, IScalableVersionAttribute, ScalableVersionAttribute } from './scalable-version-attribute';
 import { addAlias } from './util';
 
 export interface IVersion extends IFunction {
@@ -25,6 +28,12 @@ export interface IVersion extends IFunction {
    * @param options Alias options
    */
   addAlias(aliasName: string, options?: AliasOptions): Alias;
+
+  // /**
+  //  * Enables autoscaling on a version with provisioned concurrency
+  //  * @param props The properties for autoscaling
+  //  */
+  // autoScaleProvisionedConcurrency(props: EnableScalingProps): IScalableVersionAttribute;
 }
 
 /**
@@ -128,6 +137,10 @@ export class Version extends QualifiedFunctionBase implements IVersion {
       public addAlias(name: string, opts: AliasOptions = { }): Alias {
         return addAlias(this, this, name, opts);
       }
+
+      public autoScaleProvisionedConcurrency(props: EnableScalingProps): IScalableVersionAttribute {
+        return this.autoScaleProvisionedConcurrency(props);
+      }
     }
     return new Import(scope, id);
   }
@@ -147,6 +160,11 @@ export class Version extends QualifiedFunctionBase implements IVersion {
       public addAlias(name: string, opts: AliasOptions = { }): Alias {
         return addAlias(this, this, name, opts);
       }
+
+      public autoScaleProvisionedConcurrency(props: EnableScalingProps): IScalableVersionAttribute {
+        return this.autoScaleProvisionedConcurrency(props);
+      }
+
     }
     return new Import(scope, id);
   }
@@ -159,6 +177,9 @@ export class Version extends QualifiedFunctionBase implements IVersion {
   protected readonly qualifier: string;
   protected readonly canCreatePermissions = true;
 
+  private provisionedConcurrency: boolean;
+  private scalableVersion?: ScalableVersionAttribute;
+
   constructor(scope: Construct, id: string, props: VersionProps) {
     super(scope, id);
 
@@ -177,6 +198,8 @@ export class Version extends QualifiedFunctionBase implements IVersion {
       });
     }
 
+    this.provisionedConcurrency = props.provisionedConcurrentExecutions ? true : false;
+
     this.version = version.attrVersion;
     this.functionArn = version.ref;
     this.functionName = `${this.lambda.functionName}:${this.version}`;
@@ -223,6 +246,36 @@ export class Version extends QualifiedFunctionBase implements IVersion {
     return addAlias(this, this, aliasName, options);
   }
 
+  /**
+   * Enable autoscaling for the given lambda version. Requires that lambda version has provisioned concurrency.
+   * @param props The properties for autoscaling
+   */
+  public autoScaleProvisionedConcurrency(props: EnableScalingProps): IScalableVersionAttribute {
+    if (!this.provisionedConcurrency) {
+      throw new Error('Autoscaling is available for versions with provisioned concurrency only');
+    }
+    if (this.scalableVersion) {
+      throw new Error('Autoscaling already enabled for this version');
+    }
+    // Use a Service Linked Role
+    // https://docs.aws.amazon.com/autoscaling/application/userguide/application-auto-scaling-service-linked-roles.html
+    const role = iam.Role.fromRoleArn(this, 'ScalingRole', Stack.of(this).formatArn({
+      service: 'iam',
+      region: '',
+      resource: 'role/aws-service-role/lambda.application-autoscaling.amazonaws.com',
+      resourceName: 'AWSServiceRoleForApplicationAutoScaling_LambdaConcurrency',
+    }));
+
+    return this.scalableVersion = new ScalableVersionAttribute(this, 'VersionScaling', {
+      serviceNamespace: appscaling.ServiceNamespace.LAMBDA,
+      dimension: 'lambda:function:ProvisionedConcurrency',
+      minCapacity: props.minCapacity,
+      maxCapacity: props.maxCapacity,
+      resourceId: `function:${this.lambda.functionName}:${this.version}`,
+      role,
+    });
+  }
+
   /**
    * Validate that the provisionedConcurrentExecutions makes sense
    *

packages/@aws-cdk/aws-lambda/lib/scalable-version-attribute.ts

@@ -0,0 +1,65 @@
+import * as appscaling from '@aws-cdk/aws-applicationautoscaling';
+
+/**
+ * Interface for scalable attributes
+ */
+export interface IScalableVersionAttribute {
+  /**
+   * Scale out or in to keep utilization at a given level
+   */
+  scaleOnUtilization(props: UtilizationScalingProps): void;
+  /**
+   * Add scheduled scaling for this scaling attribute
+   */
+  scaleOnSchedule(id: string, actions: appscaling.ScalingSchedule): void;
+}
+
+/**
+ * Properties for enabling Lambda utilization tracking
+ */
+export interface UtilizationScalingProps extends appscaling.BaseTargetTrackingProps {
+  /**
+   * Target utilization percentage for the attribute
+   */
+  readonly targetUtilizationPercent: number;
+}
+
+/**
+ * A scalable lambda version attribute
+ */
+export class ScalableVersionAttribute extends appscaling.BaseScalableAttribute {
+  /**
+   * Scale out or in to keep utilization at a given level
+   */
+  public scaleOnUtilization(props: UtilizationScalingProps) {
+    if (props.targetUtilizationPercent < 0 || props.targetUtilizationPercent > 1) {
+      throw new Error('target utilization is a percentage and must be between 0 and 1.');
+    }
+    super.doScaleToTrackMetric('Tracking', {
+      targetValue: props.targetUtilizationPercent,
+      predefinedMetric: appscaling.PredefinedMetric.LAMBDA_PROVISIONED_CONCURRENCY_UTILIZATION,
+      ...props,
+    });
+  }
+
+  /**
+   * Scale out or in based on time
+   */
+  public scaleOnSchedule(id: string, action: appscaling.ScalingSchedule) {
+    super.doScaleOnSchedule(id, action);
+  }
+}
+
+/**
+ * Properties for enabling Lambda capacity scaling
+ */
+export interface EnableScalingProps {
+  /**
+   * Minimum capacity to scale to
+   */
+  readonly minCapacity: number;
+  /**
+   * Maximum capacity to scale to
+   */
+  readonly maxCapacity: number;
+}

packages/@aws-cdk/aws-lambda/package.json

@@ -83,6 +83,7 @@
     "sinon": "^9.0.2"
   },
   "dependencies": {
+    "@aws-cdk/aws-applicationautoscaling": "0.0.0",
     "@aws-cdk/aws-cloudwatch": "0.0.0",
     "@aws-cdk/aws-ec2": "0.0.0",
     "@aws-cdk/aws-events": "0.0.0",
@@ -97,6 +98,7 @@
   },
   "homepage": "https://github.com/aws/aws-cdk",
   "peerDependencies": {
+    "@aws-cdk/aws-applicationautoscaling": "0.0.0",
     "@aws-cdk/aws-cloudwatch": "0.0.0",
     "@aws-cdk/aws-ec2": "0.0.0",
     "@aws-cdk/aws-events": "0.0.0",
@@ -165,7 +167,10 @@
       "props-default-doc:@aws-cdk/aws-lambda.Permission.sourceArn",
       "docs-public-apis:@aws-cdk/aws-lambda.ResourceBindOptions",
       "docs-public-apis:@aws-cdk/aws-lambda.VersionAttributes",
-      "props-physical-name:@aws-cdk/aws-lambda.EventInvokeConfigProps"
+      "props-physical-name:@aws-cdk/aws-lambda.EventInvokeConfigProps",
+      "props-struct-name:@aws-cdk/aws-lambda.IScalableVersionAttribute",
+      "construct-ctor-props-type:@aws-cdk/aws-lambda.ScalableVersionAttribute",
+      "construct-interface-extends-iconstruct:@aws-cdk/aws-lambda.IScalableVersionAttribute"
     ]
   },
   "stability": "stable",