fix(aws-cdk): fix bug in SSM Parameter Provider (#1023)

SSM Parameter Provider Plugin was not properly updated
for the new context provider protocol. It is now,
 and an integ test is added.

packages/aws-cdk/integ-tests/app/app.js

@@ -5,6 +5,9 @@ class MyStack extends cdk.Stack {
   constructor(parent, id) {
     super(parent, id);
     new sns.Topic(this, 'topic');
+
+    console.log(new cdk.AvailabilityZoneProvider(this).availabilityZones);
+    console.log(new cdk.SSMParameterProvider(this, { parameterName: '/aws/service/ami-amazon-linux-latest/amzn2-ami-hvm-x86_64-gp2' }).parameterValue(''));
   }
 }
 
@@ -21,4 +24,4 @@ const app = new cdk.App();
 new MyStack(app, 'cdk-toolkit-integration-test-1');
 new YourStack(app, 'cdk-toolkit-integration-test-2');
 
-app.run();
+app.run();

packages/aws-cdk/lib/contextplugins.ts

@@ -38,16 +38,16 @@ export class SSMContextProviderPlugin implements ContextProviderPlugin {
   public async getValue(args: {[key: string]: any}) {
     const region = args.region;
     const account = args.account;
-    if (!('parameterName' in args.props)) {
+    if (!('parameterName' in args)) {
         throw new Error('parameterName must be provided in props for SSMContextProviderPlugin');
     }
-    const parameterName = args.props.parameterName;
+    const parameterName = args.parameterName;
     debug(`Reading SSM parameter ${account}:${region}:${parameterName}`);
 
     const ssm = await this.aws.ssm(account, region, Mode.ForReading);
     const response = await ssm.getParameter({ Name: parameterName }).promise();
     if (!response.Parameter || response.Parameter.Value === undefined) {
-      throw new Error(`SSM parameter not availble in account ${account}, region ${region}: ${parameterName}`);
+      throw new Error(`SSM parameter not available in account ${account}, region ${region}: ${parameterName}`);
     }
     return response.Parameter.Value;
   }