fix(route53): value is too long error for TXT records (#9984)

The solution is to split the record strings over 255 characters into multiple text strings within the same record. See https://aws.amazon.com/premiumsupport/knowledge-center/route53-resolve-dkim-text-record-error/ Fixes #8244 ---- *By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*
aws · Aug 27, 2020 · fd4be21 · fd4be21
1 parent 352d25a
commit fd4be21
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diff --git a/packages/@aws-cdk/aws-route53/lib/record-set.ts b/packages/@aws-cdk/aws-route53/lib/record-set.ts
@@ -322,11 +322,31 @@ export class TxtRecord extends RecordSet {
     super(scope, id, {
       ...props,
       recordType: RecordType.TXT,
-      target: RecordTarget.fromValues(...props.values.map(v => JSON.stringify(v))),
+      target: RecordTarget.fromValues(...props.values.map(v => formatTxt(v))),
     });
   }
 }
 
+/**
+ * Formats a text value for use in a TXT record
+ *
+ * Use `JSON.stringify` to correctly escape and enclose in double quotes ("").
+ *
+ * DNS TXT records can contain up to 255 characters in a single string. TXT
+ * record strings over 255 characters must be split into multiple text strings
+ * within the same record.
+ *
+ * @see https://aws.amazon.com/premiumsupport/knowledge-center/route53-resolve-dkim-text-record-error/
+ */
+function formatTxt(string: string): string {
+  const result = [];
+  let idx = 0;
+  while (idx < string.length) {
+    result.push(string.slice(idx, idx += 255)); // chunks of 255 characters long
+  }
+  return result.map(r => JSON.stringify(r)).join('');
+}
+
 /**
  * Properties for a SRV record value.
  */

diff --git a/packages/@aws-cdk/aws-route53/test/integ.route53.expected.json b/packages/@aws-cdk/aws-route53/test/integ.route53.expected.json
@@ -298,6 +298,20 @@
         ],
         "TTL": "1800"
       }
+    },
+    "TXT0D5C5ACF": {
+      "Type": "AWS::Route53::RecordSet",
+      "Properties": {
+        "Name": "cdk.test.",
+        "Type": "TXT",
+        "HostedZoneId": {
+          "Ref": "PublicZone2E1C4E34"
+        },
+        "ResourceRecords": [
+          "\"this is a very long stringthis is a very long stringthis is a very long stringthis is a very long stringthis is a very long stringthis is a very long stringthis is a very long stringthis is a very long stringthis is a very long stringthis is a very long s\"\"tring\""
+        ],
+        "TTL": "1800"
+      }
     }
   },
   "Outputs": {

diff --git a/packages/@aws-cdk/aws-route53/test/integ.route53.ts b/packages/@aws-cdk/aws-route53/test/integ.route53.ts
@@ -46,6 +46,13 @@ new CaaAmazonRecord(stack, 'CaaAmazon', {
   zone: publicZone,
 });
 
+new TxtRecord(stack, 'TXT', {
+  zone: publicZone,
+  values: [
+    'this is a very long string'.repeat(10),
+  ],
+});
+
 new cdk.CfnOutput(stack, 'PrivateZoneId', { value: privateZone.hostedZoneId });
 new cdk.CfnOutput(stack, 'PublicZoneId', { value: publicZone.hostedZoneId });
 

diff --git a/packages/@aws-cdk/aws-route53/test/test.record-set.ts b/packages/@aws-cdk/aws-route53/test/test.record-set.ts
@@ -295,6 +295,36 @@ export = {
     test.done();
   },
 
+  'TXT record with value longer than 255 chars'(test: Test) {
+    // GIVEN
+    const stack = new Stack();
+
+    const zone = new route53.HostedZone(stack, 'HostedZone', {
+      zoneName: 'myzone',
+    });
+
+    // WHEN
+    new route53.TxtRecord(stack, 'TXT', {
+      zone,
+      recordName: 'www',
+      values: ['hello'.repeat(52)],
+    });
+
+    // THEN
+    expect(stack).to(haveResource('AWS::Route53::RecordSet', {
+      Name: 'www.myzone.',
+      Type: 'TXT',
+      HostedZoneId: {
+        Ref: 'HostedZoneDB99F866',
+      },
+      ResourceRecords: [
+        '"hellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohellohello""hello"',
+      ],
+      TTL: '1800',
+    }));
+    test.done();
+  },
+
   'SRV record'(test: Test) {
     // GIVEN
     const stack = new Stack();