tehlers320 / autoscaling-route53-lambda

autoscaling-route53-lambda

This code can be used to manage Route53 records of type CNAME or A for an Autoscaling Group with Lambda via a tag on the ASG. The main function listens for TERMINATE and LAUNCH events, and DELETEs and UPSERTs records to Route53.

Usage

Create an Autoscaling Group Tag called Route53 with values in any of the formats below.

Tag Name: Route53 (defined in TAG_NAME variable)

Tag value formats:

Basics and optional parameters

Format	Example	Notes
HostedZoneId:record-name	Z0987654321123:www.example.com	Assumes CNAME type and TTL of 1
HostedZoneId:type:record-name	Z0987654321123:CNAME:www.example.com	Assumes TTL of 1
HostedZoneId:type:record-name:ttl	Z0987654321123:CNAME:www.example.com:30

Prefix-notation

Format	Example	Notes
ZoneId:type:record-name:ttl	Z0987654321123:CNAME:www.#:30	# will be replaced by the zone name, ex: www.# -- will be replaced with --> www.example.com

Simple Multiple zone format

Format	Example	Notes
ZoneId1,ZoneId2,...:prefix-name	Z0987654321123,Z1234567890123:www.:30	All zones use the same prefix-name and prefix-name is added to zone name

JSON Multiple zone format

Format	Example	Notes
[<valid string 1>, <valid string 2>, ...]	["Z0987654321123:CNAME:www.example.com:30","Z1234567890123:A:www.#"]	JSON array of strings which are in a valid format above

NOTE: A tag value of <empty string> or none is ignored.

ZIP it up

Create ZIP file with zip ../autoscaling-route53.js index.js async

Install (for lack of better words)

AWS makes this relatively easy for you, but you still have to jump some hoops. Let's use the Console for this, as it is easiest.

For a given Autoscaling Group you want to 'sync' with Route53, do the following:

1. create an IAM role with policies AmazonEC2ReadOnlyAccess, CloudWatchLogsFullAccess and AmazonRoute53FullAccess (our name is AutoscalingRoute53Role)
2. create a Lambda function with ZIP and IAM Role from before (our name is autoscalingRoute53)
3. create an SNS topic (our topic name asg-notifications-staging-elasticsearch-30mhz-com)
4. add a subscription to SNS topic, pointing to the Lambda function
5. on the notifications tab in the details pane of the Autoscaling Group, you click 'Create notification'
6. set 'send notification to' to the SNS topic
7. and only 'launch' and 'terminate' are used by this lambda function. Other messages are ignored.
8. last, but not least, add a tag to the Autoscaling Group with key 'Route53' and value 'HostedZoneId:record-name'

And now, scale :)

Using Cloudformation

If you want to script this setup with Cloudformation, here is a snippet that covers steps 3 - 7 above. This snippet would be put into the 'Resources' of a Cloudformation script.

"Resources": {

  ....

    "LambdaDNS": {
        "Type": "AWS::Lambda::Function",
        "Properties": {
            "FunctionName" : "asg-to-dns-v1",
            "Code": {
                "S3Bucket": "bionano-devops-build-artifacts",
                "S3Key": "lambdas/lambdaDNS/autoscaling-route53.js.zip"
            },
            "Description" : "Lambda to update dns based on asg events", 
            "Role": { "Fn::Join" : [ "/", [ "arn:aws:iam::123456789012:role", "lambda-asg-sns-dns"] ] },
            "Timeout": 60,
            "Handler": "index.handler",
            "Runtime": "nodejs4.3",
            "MemorySize": 128
        }
    },

    "autoscalingNotificationTopic" : {
      "Type" : "AWS::SNS::Topic",
      "DependsOn" : [ "LambdaDNS" ], 
      "Condition": "IsUSWest2",
      "Properties" : {
        "DisplayName" : "wD Scaling",
        "Subscription" : [ 
            { "Endpoint"  : {"Fn::GetAtt" : [ "LambdaDNS", "Arn" ]}, "Protocol"  : "lambda" }
        ],
       "TopicName" : "dev-autoscaling-NotificationTopic"
      }
    },      

    "LambdaInvokePermission": {
        "Type": "AWS::Lambda::Permission",
        "Condition": "IsUSWest2",
        "DependsOn" : [ "LambdaDNS", "autoscalingNotificationTopic" ], 
        "Properties": {
          "Action": "lambda:InvokeFunction",
          "Principal": "sns.amazonaws.com",
          "SourceArn": { "Ref": "autoscalingNotificationTopic" },
          "FunctionName": { "Fn::GetAtt": [ "LambdaDNS", "Arn" ] }
        }
    }
  .....