feat(appsync): allow configuring API key authorization mode

By default, the AppSync L2 constructs use API key authorization, but it
doesn't allow configuring the API key.

Fix that by allowing a default authorization mode to be specified.
Currently, the supported modes are Cognito user pools and API keys. When
specifying API key authorization, allow configuring it.

BREAKING CHANGE:
    Configuration the user pool authorization is now done through the
    authorizationConfig property. This allows us to specify a default
    authorization mode out of the supported ones, currently limited to
    Cognito user pools and API keys.

Fixes aws#6246

Signed-off-by: Duarte Nunes <duarte@uma.ni>

packages/@aws-cdk/aws-appsync/README.md

@@ -59,9 +59,11 @@ export class ApiStack extends Stack {
       logConfig: {
         fieldLogLevel: FieldLogLevel.ALL,
       },
-      userPoolConfig: {
-        userPool,
-        defaultAction: UserPoolDefaultAction.ALLOW,
+      authorizationConfig: {
+        defaultAuthorization: {
+          userPool,
+          defaultAction: UserPoolDefaultAction.ALLOW,
+        },
       },
       schemaDefinitionFile: './schema.graphql',
     });

packages/@aws-cdk/aws-appsync/lib/graphqlapi.ts

@@ -2,9 +2,9 @@ import { IUserPool } from "@aws-cdk/aws-cognito";
 import { Table } from '@aws-cdk/aws-dynamodb';
 import { IGrantable, IPrincipal, IRole, ManagedPolicy, Role, ServicePrincipal } from "@aws-cdk/aws-iam";
 import { IFunction } from "@aws-cdk/aws-lambda";
-import { Construct, IResolvable } from "@aws-cdk/core";
+import { Construct, Duration, IResolvable } from "@aws-cdk/core";
 import { readFileSync } from "fs";
-import { CfnDataSource, CfnGraphQLApi, CfnGraphQLSchema, CfnResolver } from "./appsync.generated";
+import { CfnApiKey, CfnDataSource, CfnGraphQLApi, CfnGraphQLSchema, CfnResolver } from "./appsync.generated";
 
 /**
  * enum with all possible values for Cognito user-pool default actions
@@ -43,6 +43,45 @@ export interface UserPoolConfig {
     readonly defaultAction?: UserPoolDefaultAction;
 }
 
+function isUserPoolConfig(obj: unknown): obj is UserPoolConfig {
+    return (obj as UserPoolConfig).userPool !== undefined;
+}
+
+/**
+ * Configuration for API Key authorization in AppSync
+ */
+export interface ApiKeyConfig {
+    /**
+     * Unique description of the API key.
+     */
+    readonly apiKeyDesc: string;
+
+    /**
+     * Expiration time of the API key with a minimum of 1 day
+     * and a maximum of 365 days.
+     * @default - 7 days.
+     */
+    readonly expires?: Duration;
+}
+
+function isApiKeyConfig(obj: unknown): obj is ApiKeyConfig {
+    return (obj as ApiKeyConfig).apiKeyDesc !== undefined;
+}
+
+type AuthModes = UserPoolConfig | ApiKeyConfig;
+
+/**
+ * Marker interface for the different authorization modes.
+ */
+export interface AuthorizationConfig {
+    /**
+     * Optional authorization configuration
+     *
+     * @default - API Key authorization
+     */
+    readonly defaultAuthorization?: AuthModes;
+}
+
 /**
  * log-level for fields in AppSync
  */
@@ -90,11 +129,11 @@ export interface GraphQLApiProps {
     readonly name: string;
 
     /**
-     * Optional user pool authorizer configuration
+     * Optional authorization configuration
      *
-     * @default - Do not use Cognito auth
+     * @default - API Key authorization
      */
-    readonly userPoolConfig?: UserPoolConfig;
+    readonly authorizationConfig?: AuthorizationConfig;
 
     /**
      * Logging configuration for this api
@@ -145,7 +184,6 @@ export class GraphQLApi extends Construct {
     public readonly schema: CfnGraphQLSchema;
 
     private api: CfnGraphQLApi;
-    private authenticationType: string;
 
     constructor(scope: Construct, id: string, props: GraphQLApiProps) {
         super(scope, id);
@@ -156,22 +194,9 @@ export class GraphQLApi extends Construct {
             apiLogsRole.addManagedPolicy(ManagedPolicy.fromAwsManagedPolicyName('service-role/AWSAppSyncPushToCloudWatchLogs'));
         }
 
-        if (props.userPoolConfig) {
-            this.authenticationType = 'AMAZON_COGNITO_USER_POOLS';
-        } else {
-            this.authenticationType = 'API_KEY';
-        }
-
         this.api = new CfnGraphQLApi(this, 'Resource', {
             name: props.name,
-            authenticationType: this.authenticationType,
-            ...props.userPoolConfig && {
-                userPoolConfig: {
-                    userPoolId: props.userPoolConfig.userPool.userPoolId,
-                    awsRegion: props.userPoolConfig.userPool.stack.region,
-                    defaultAction: props.userPoolConfig.defaultAction ? props.userPoolConfig.defaultAction.toString() : 'ALLOW',
-                },
-            },
+            authenticationType: 'API_KEY',
             ...props.logConfig && {
                 logConfig: {
                     cloudWatchLogsRoleArn: apiLogsRole ? apiLogsRole.roleArn : undefined,
@@ -186,6 +211,10 @@ export class GraphQLApi extends Construct {
         this.graphQlUrl = this.api.attrGraphQlUrl;
         this.name = this.api.name;
 
+        if (props.authorizationConfig) {
+            this.setupAuth(props.authorizationConfig);
+        }
+
         let definition;
         if (props.schemaDefinition) {
             definition = props.schemaDefinition;
@@ -230,6 +259,40 @@ export class GraphQLApi extends Construct {
         });
     }
 
+    private setupAuth(auth: AuthorizationConfig) {
+        if (isUserPoolConfig(auth.defaultAuthorization)) {
+            const { authenticationType, userPoolConfig } = this.userPoolDescFrom(auth.defaultAuthorization);
+            this.api.authenticationType = authenticationType;
+            this.api.userPoolConfig = userPoolConfig;
+        } else if (isApiKeyConfig(auth.defaultAuthorization)) {
+            this.api.authenticationType = this.apiKeyDesc(auth.defaultAuthorization).authenticationType;
+        }
+    }
+
+    private userPoolDescFrom(upConfig: UserPoolConfig): { authenticationType: string; userPoolConfig: CfnGraphQLApi.UserPoolConfigProperty } {
+        return {
+            authenticationType: 'AMAZON_COGNITO_USER_POOLS',
+            userPoolConfig: {
+                appIdClientRegex: upConfig.appIdClientRegex,
+                userPoolId: upConfig.userPool.userPoolId,
+                awsRegion: upConfig.userPool.stack.region,
+                defaultAction: upConfig.defaultAction ? upConfig.defaultAction.toString() : 'ALLOW',
+            }
+        };
+    }
+
+    private apiKeyDesc(akConfig: ApiKeyConfig): { authenticationType: string } {
+        const expires = akConfig.expires || Duration.days(7);
+        if (expires.toDays() < 1 || expires.toDays() > 366) {
+            throw Error("API key expiration must be between 1 and 365 days.");
+        }
+        new CfnApiKey(this, `${akConfig.apiKeyDesc || ''}ApiKey`, {
+            expires: Math.round(Date.now() / 1000) + expires.toSeconds(),
+            description: akConfig.apiKeyDesc,
+            apiId: this.apiId,
+        });
+        return { authenticationType: 'API_KEY' };
+    }
 }
 
 /**