feat(@aws-cdk/aws-ec2): make GenericMachineImage use CfnMapping in an…

… agnostic stack (#8759)
aws · Jan 17, 2021 · c322545 · c322545
1 parent ea67c54
commit c322545
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Showing 4 changed files with 71 additions and 27 deletions.
diff --git a/packages/@aws-cdk/aws-ec2/README.md b/packages/@aws-cdk/aws-ec2/README.md
@@ -504,6 +504,9 @@ examples of things you might want to use:
 > [Runtime Context](https://docs.aws.amazon.com/cdk/latest/guide/context.html) in the CDK
 > developer guide.
 
+> NOTE: `MachineImage.genericLinux()`, `MachineImage.genericWindows()` will use `CfnMapping` in
+> an agnostic stack.
+
 ## Special VPC configurations
 
 ### VPN connections to a VPC

diff --git a/packages/@aws-cdk/aws-ec2/lib/machine-image.ts b/packages/@aws-cdk/aws-ec2/lib/machine-image.ts
@@ -1,6 +1,6 @@
 import * as ssm from '@aws-cdk/aws-ssm';
 import * as cxschema from '@aws-cdk/cloud-assembly-schema';
-import { Construct, ContextProvider, Stack, Token } from '@aws-cdk/core';
+import { Construct, ContextProvider, CfnMapping, Aws } from '@aws-cdk/core';
 import * as cxapi from '@aws-cdk/cx-api';
 import { UserData } from './user-data';
 import { WindowsVersion } from './windows-versions';
@@ -363,22 +363,25 @@ export interface GenericWindowsImageProps {
  * manually specify an AMI map.
  */
 export class GenericLinuxImage implements IMachineImage {
-  constructor(private readonly amiMap: {[region: string]: string}, private readonly props: GenericLinuxImageProps = {}) {
-  }
-
-  public getImage(scope: Construct): MachineImageConfig {
-    const region = Stack.of(scope).region;
-    if (Token.isUnresolved(region)) {
-      throw new Error('Unable to determine AMI from AMI map since stack is region-agnostic');
-    }
+  private mapping: { [k1: string]: { [k2: string]: any } } = {};
 
-    const ami = region !== 'test-region' ? this.amiMap[region] : 'ami-12345';
-    if (!ami) {
-      throw new Error(`Unable to find AMI in AMI map: no AMI specified for region '${region}'`);
+  /**
+   * A Linux image where you specify the AMI ID for every region
+   *
+   * @param amiMap For every region where you are deploying the stack,
+   * specify the AMI ID for that region.
+   * @param props Customize the image by supplying additional props
+   */
+  constructor(readonly amiMap: { [region: string]: string }, private readonly props: GenericLinuxImageProps = {}) {
+    for (const [region, ami] of Object.entries(amiMap)) {
+      this.mapping[region] = { ami };
     }
+  }
 
+  public getImage(scope: Construct): MachineImageConfig {
+    const amiMap = new CfnMapping(scope, 'AmiMap', { mapping: this.mapping });
     return {
-      imageId: ami,
+      imageId: amiMap.findInMap(Aws.REGION, 'ami'),
       userData: this.props.userData ?? UserData.forLinux(),
       osType: OperatingSystemType.LINUX,
     };
@@ -391,22 +394,25 @@ export class GenericLinuxImage implements IMachineImage {
  * Allows you to create a generic Windows EC2 , manually specify an AMI map.
  */
 export class GenericWindowsImage implements IMachineImage {
-  constructor(private readonly amiMap: {[region: string]: string}, private readonly props: GenericWindowsImageProps = {}) {
-  }
-
-  public getImage(scope: Construct): MachineImageConfig {
-    const region = Stack.of(scope).region;
-    if (Token.isUnresolved(region)) {
-      throw new Error('Unable to determine AMI from AMI map since stack is region-agnostic');
-    }
+  private mapping: { [k1: string]: { [k2: string]: any } } = {};
 
-    const ami = region !== 'test-region' ? this.amiMap[region] : 'ami-12345';
-    if (!ami) {
-      throw new Error(`Unable to find AMI in AMI map: no AMI specified for region '${region}'`);
+  /**
+   * A Windows image where you specify the AMI ID for every region
+   *
+   * @param amiMap For every region where you are deploying the stack,
+   * specify the AMI ID for that region.
+   * @param props Customize the image by supplying additional props
+   */
+  constructor(readonly amiMap: {[region: string]: string}, private readonly props: GenericWindowsImageProps = {}) {
+    for (const [region, ami] of Object.entries(amiMap)) {
+      this.mapping[region] = { ami };
     }
+  }
 
+  public getImage(scope: Construct): MachineImageConfig {
+    const amiMap = new CfnMapping(scope, 'AmiMap', { mapping: this.mapping });
     return {
-      imageId: ami,
+      imageId: amiMap.findInMap(Aws.REGION, 'ami'),
       userData: this.props.userData ?? UserData.forWindows(),
       osType: OperatingSystemType.WINDOWS,
     };

diff --git a/packages/@aws-cdk/aws-ec2/test/machine-image.test.ts b/packages/@aws-cdk/aws-ec2/test/machine-image.test.ts
@@ -1,3 +1,4 @@
+import { expect as cdkExpect, matchTemplate, MatchStyle } from '@aws-cdk/assert';
 import { App, Stack } from '@aws-cdk/core';
 import * as ec2 from '../lib';
 
@@ -11,6 +12,29 @@ beforeEach(() => {
   });
 });
 
+test('can make and use a Linux image', () => {
+  // WHEN
+  const image = new ec2.GenericLinuxImage({
+    testregion: 'ami-1234',
+  });
+
+  // THEN
+  const details = image.getImage(stack);
+  const expected = {
+    Mappings: {
+      AmiMap: {
+        testregion: {
+          ami: 'ami-1234',
+        },
+      },
+    },
+  };
+
+  cdkExpect(stack).to(matchTemplate(expected, MatchStyle.EXACT));
+  expect(stack.resolve(details.imageId)).toEqual({ 'Fn::FindInMap': ['AmiMap', { Ref: 'AWS::Region' }, 'ami'] });
+  expect(details.osType).toEqual(ec2.OperatingSystemType.LINUX);
+});
+
 test('can make and use a Windows image', () => {
   // WHEN
   const image = new ec2.GenericWindowsImage({
@@ -19,7 +43,18 @@ test('can make and use a Windows image', () => {
 
   // THEN
   const details = image.getImage(stack);
-  expect(details.imageId).toEqual('ami-1234');
+  const expected = {
+    Mappings: {
+      AmiMap: {
+        testregion: {
+          ami: 'ami-1234',
+        },
+      },
+    },
+  };
+
+  cdkExpect(stack).to(matchTemplate(expected, MatchStyle.EXACT));
+  expect(stack.resolve(details.imageId)).toEqual({ 'Fn::FindInMap': ['AmiMap', { Ref: 'AWS::Region' }, 'ami'] });
   expect(details.osType).toEqual(ec2.OperatingSystemType.WINDOWS);
 });
 

diff --git a/packages/@aws-cdk/aws-ec2/test/vpc.test.ts b/packages/@aws-cdk/aws-ec2/test/vpc.test.ts
@@ -895,7 +895,7 @@ nodeunitShim({
       // THEN
       expect(stack).to(countResources('AWS::EC2::Instance', 3));
       expect(stack).to(haveResource('AWS::EC2::Instance', {
-        ImageId: 'ami-1',
+        ImageId: { 'Fn::FindInMap': ['TheVPCPublicSubnet1NatInstanceAmiMap7BC63154', { Ref: 'AWS::Region' }, 'ami'] },
         InstanceType: 'q86.mega',
         SourceDestCheck: false,
       }));