Framework: Tokens can be converted to strings

Tokens (such as resource attributes) can now be implicitly converted into strings. Parameters and attributes can now be combined into larger strings using the native string facilities of the host language. The process will be reversed by the resolve() function during synthesis, which will split the string up again into string literals and CloudFormation intrinsics. The same transformation is applied during JSON.stringify(), so that Tokens in a complex JSON structure are preserved. Fixes #24 and #168.
aws · Aug 7, 2018 · 3796389 · 3796389
1 parent 9f0b114
commit 3796389
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diff --git a/packages/@aws-cdk/aws-cloudwatch/lib/dashboard.ts b/packages/@aws-cdk/aws-cloudwatch/lib/dashboard.ts
@@ -1,4 +1,4 @@
-import { Construct, Stack, Token, tokenAwareJsonify } from "@aws-cdk/cdk";
+import { Construct, Stack, Token } from "@aws-cdk/cdk";
 import { cloudformation } from './cloudwatch.generated';
 import { Column, Row } from "./layout";
 import { IWidget } from "./widget";
@@ -33,7 +33,7 @@ export class Dashboard extends Construct {
             dashboardBody: new Token(() => {
                 const column = new Column(...this.rows);
                 column.position(0, 0);
-                return tokenAwareJsonify({ widgets: column.toJson() });
+                return JSON.stringify({ widgets: column.toJson() });
             })
         });
     }

diff --git a/packages/@aws-cdk/aws-cloudwatch/test/integ.alarm-and-dashboard.expected.json b/packages/@aws-cdk/aws-cloudwatch/test/integ.alarm-and-dashboard.expected.json
@@ -7,6 +7,11 @@
       "Type": "AWS::CloudWatch::Alarm",
       "Properties": {
         "ComparisonOperator": "GreaterThanOrEqualToThreshold",
+        "EvaluationPeriods": 3,
+        "MetricName": "ApproximateNumberOfMessagesVisible",
+        "Namespace": "AWS/SQS",
+        "Period": 300,
+        "Threshold": 100,
         "Dimensions": [
           {
             "Name": "QueueName",
@@ -18,41 +23,55 @@
             }
           }
         ],
-        "EvaluationPeriods": 3,
-        "MetricName": "ApproximateNumberOfMessagesVisible",
-        "Namespace": "AWS/SQS",
-        "Period": 300,
-        "Statistic": "Average",
-        "Threshold": 100
+        "Statistic": "Average"
       }
     },
     "DashCCD7F836": {
       "Type": "AWS::CloudWatch::Dashboard",
       "Properties": {
-        "DashboardName": "aws-cdk-cloudwatch-DashCCD7F836",
         "DashboardBody": {
-          "Fn::Sub": [
-            "{\"widgets\":[{\"type\":\"text\",\"width\":6,\"height\":2,\"x\":0,\"y\":0,\"properties\":{\"markdown\":\"# This is my dashboard\"}},{\"type\":\"text\",\"width\":6,\"height\":2,\"x\":6,\"y\":0,\"properties\":{\"markdown\":\"you like?\"}},{\"type\":\"metric\",\"width\":6,\"height\":6,\"x\":0,\"y\":2,\"properties\":{\"view\":\"timeSeries\",\"title\":\"Messages in queue\",\"region\":\"${ref0}\",\"annotations\":{\"alarms\":[\"${ref1}\"]},\"yAxis\":{\"left\":{\"min\":0}}}},{\"type\":\"metric\",\"width\":6,\"height\":6,\"x\":0,\"y\":8,\"properties\":{\"view\":\"timeSeries\",\"title\":\"More messages in queue with alarm annotation\",\"region\":\"${ref0}\",\"metrics\":[[\"AWS/SQS\",\"ApproximateNumberOfMessagesVisible\",\"QueueName\",\"${ref2}\",{\"yAxis\":\"left\",\"period\":300,\"stat\":\"Average\"}]],\"annotations\":{\"horizontal\":[{\"label\":\"ApproximateNumberOfMessagesVisible >= 100 for 3 datapoints within 15 minutes\",\"value\":100,\"yAxis\":\"left\"}]},\"yAxis\":{\"left\":{\"min\":0},\"right\":{\"min\":0}}}},{\"type\":\"metric\",\"width\":6,\"height\":3,\"x\":0,\"y\":14,\"properties\":{\"view\":\"singleValue\",\"title\":\"Current messages in queue\",\"region\":\"${ref0}\",\"metrics\":[[\"AWS/SQS\",\"ApproximateNumberOfMessagesVisible\",\"QueueName\",\"${ref2}\",{\"yAxis\":\"left\",\"period\":300,\"stat\":\"Average\"}]]}}]}",
-            {
-              "ref0": {
+          "Fn::Join": [
+            "",
+            [
+              "{\"widgets\":[{\"type\":\"text\",\"width\":6,\"height\":2,\"x\":0,\"y\":0,\"properties\":{\"markdown\":\"# This is my dashboard\"}},{\"type\":\"text\",\"width\":6,\"height\":2,\"x\":6,\"y\":0,\"properties\":{\"markdown\":\"you like?\"}},{\"type\":\"metric\",\"width\":6,\"height\":6,\"x\":0,\"y\":2,\"properties\":{\"view\":\"timeSeries\",\"title\":\"Messages in queue\",\"region\":\"",
+              {
                 "Ref": "AWS::Region"
               },
-              "ref1": {
+              "\",\"annotations\":{\"alarms\":[\"",
+              {
                 "Fn::GetAtt": [
                   "Alarm7103F465",
                   "Arn"
                 ]
               },
-              "ref2": {
+              "\"]},\"yAxis\":{\"left\":{\"min\":0}}}},{\"type\":\"metric\",\"width\":6,\"height\":6,\"x\":0,\"y\":8,\"properties\":{\"view\":\"timeSeries\",\"title\":\"More messages in queue with alarm annotation\",\"region\":\"",
+              {
+                "Ref": "AWS::Region"
+              },
+              "\",\"metrics\":[[\"AWS/SQS\",\"ApproximateNumberOfMessagesVisible\",\"QueueName\",\"",
+              {
                 "Fn::GetAtt": [
                   "queue",
                   "QueueName"
                 ]
-              }
-            }
+              },
+              "\",{\"yAxis\":\"left\",\"period\":300,\"stat\":\"Average\"}]],\"annotations\":{\"horizontal\":[{\"label\":\"ApproximateNumberOfMessagesVisible >= 100 for 3 datapoints within 15 minutes\",\"value\":100,\"yAxis\":\"left\"}]},\"yAxis\":{\"left\":{\"min\":0},\"right\":{\"min\":0}}}},{\"type\":\"metric\",\"width\":6,\"height\":3,\"x\":0,\"y\":14,\"properties\":{\"view\":\"singleValue\",\"title\":\"Current messages in queue\",\"region\":\"",
+              {
+                "Ref": "AWS::Region"
+              },
+              "\",\"metrics\":[[\"AWS/SQS\",\"ApproximateNumberOfMessagesVisible\",\"QueueName\",\"",
+              {
+                "Fn::GetAtt": [
+                  "queue",
+                  "QueueName"
+                ]
+              },
+              "\",{\"yAxis\":\"left\",\"period\":300,\"stat\":\"Average\"}]]}}]}"
+            ]
           ]
-        }
+        },
+        "DashboardName": "aws-cdk-cloudwatch-DashCCD7F836"
       }
     }
   }
-}
+}
diff --git a/packages/@aws-cdk/aws-cloudwatch/test/test.dashboard.ts b/packages/@aws-cdk/aws-cloudwatch/test/test.dashboard.ts
@@ -70,7 +70,7 @@ export = {
         test.done();
     },
 
-    'tokens in widgets are retained through FnSub'(test: Test) {
+    'tokens in widgets are retained'(test: Test) {
         // GIVEN
         const stack = new Stack();
         const dashboard = new Dashboard(stack, 'Dash');
@@ -82,14 +82,11 @@ export = {
 
         // THEN
         expect(stack).to(haveResource('AWS::CloudWatch::Dashboard', {
-            DashboardBody: { "Fn::Sub": [
-                // tslint:disable-next-line:max-line-length
-                "{\"widgets\":[{\"type\":\"metric\",\"width\":1,\"height\":1,\"x\":0,\"y\":0,\"properties\":{\"view\":\"timeSeries\",\"region\":\"${ref0}\",\"metrics\":[],\"annotations\":{\"horizontal\":[]},\"yAxis\":{\"left\":{\"min\":0},\"right\":{\"min\":0}}}}]}",
-                {
-                  ref0: { Ref: "AWS::Region" }
-                }
-              ]
-            }
+            DashboardBody: { "Fn::Join": [ "", [
+                "{\"widgets\":[{\"type\":\"metric\",\"width\":1,\"height\":1,\"x\":0,\"y\":0,\"properties\":{\"view\":\"timeSeries\",\"region\":\"",
+                { Ref: "AWS::Region" },
+                "\",\"metrics\":[],\"annotations\":{\"horizontal\":[]},\"yAxis\":{\"left\":{\"min\":0},\"right\":{\"min\":0}}}}]}"
+            ]]}
         }));
 
         test.done();

diff --git a/packages/@aws-cdk/cdk/lib/cloudformation/pseudo.ts b/packages/@aws-cdk/cdk/lib/cloudformation/pseudo.ts
@@ -1,8 +1,8 @@
-import { Token } from '../core/tokens';
+import { HintedToken } from '../core/tokens';
 
-export class PseudoParameter extends Token {
+export class PseudoParameter extends HintedToken {
     constructor(name: string) {
-        super(() => ({ Ref: name }));
+        super(name, () => ({ Ref: name }));
     }
 }
 

diff --git a/packages/@aws-cdk/cdk/lib/cloudformation/resource.ts b/packages/@aws-cdk/cdk/lib/cloudformation/resource.ts
@@ -1,5 +1,5 @@
 import { Construct } from '../core/construct';
-import { Token } from '../core/tokens';
+import { HintedToken, Token } from '../core/tokens';
 import { capitalizePropertyNames, ignoreEmpty } from '../core/util';
 import { Condition } from './condition';
 import { CreationPolicy, DeletionPolicy, UpdatePolicy } from './resource-policy';
@@ -82,7 +82,7 @@ export class Resource extends Referenceable {
      * @param attributeName The name of the attribute.
      */
     public getAtt(attributeName: string): Token {
-        return new Token(() => ({ 'Fn::GetAtt': [this.logicalId, attributeName] }));
+        return new HintedToken(`${this.logicalId}.${attributeName}`, () => ({ 'Fn::GetAtt': [this.logicalId, attributeName] }));
     }
 
     /**

diff --git a/packages/@aws-cdk/cdk/lib/cloudformation/stack.ts b/packages/@aws-cdk/cdk/lib/cloudformation/stack.ts
@@ -1,7 +1,7 @@
 import cxapi = require('@aws-cdk/cx-api');
 import { App } from '../app';
 import { Construct, PATH_SEP } from '../core/construct';
-import { resolve, Token } from '../core/tokens';
+import { HintedToken, resolve, Token } from '../core/tokens';
 import { Environment } from '../environment';
 import { HashedAddressingScheme, IAddressingScheme, LogicalIDs } from './logical-id';
 import { Resource } from './resource';
@@ -392,7 +392,7 @@ export abstract class Referenceable extends StackElement {
      * Returns a token to a CloudFormation { Ref } that references this entity based on it's logical ID.
      */
     public get ref() {
-        return new Token(() => ({ Ref: this.logicalId }));
+        return new HintedToken(`${this.logicalId}`, () => ({ Ref: this.logicalId }));
     }
 }
 

diff --git a/packages/@aws-cdk/cdk/lib/cloudformation/token-aware-jsonify.ts b/packages/@aws-cdk/cdk/lib/cloudformation/token-aware-jsonify.ts