Building Serverless Architectures: Unleash the power of AWS Lambdas for your applications

Category: Programming
Author: Cagatay Gurturk
3.9
This Month Stack Overflow 1

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by anonymous   2019-01-13

AWS::Lambda::Version is not useful. You have to add a new resource for every Lambda version. If you want to publish a new version for every Cloudformation update, you have to hack the system.

I solved this issue creating a Lambda backed custom resource which is triggered for every deployment. Inside this Lambda, I am creating a new version for the Lambda function given in parameter.

For the Lambda's source you can check http://serverless-arch-eu-west-1.s3.amazonaws.com/serverless.zip

Here is the example Cloudformation using this Deployment Lambda function (You might need some modification):

{
  "AWSTemplateFormatVersion": "2010-09-09",
  "Parameters": {
    "DeploymentTime": {
      "Type": "String",
      "Description": "It is a timestamp value which shows the deployment time. Used to rotate sources."
    }
  },
  "Resources": {
    "LambdaFunctionToBeVersioned": {
      "Type": "HERE_DEFINE_YOUR_LAMBDA"
    },
    "DeploymentLambdaRole": {
      "Type": "AWS::IAM::Role",
      "Properties": {
        "AssumeRolePolicyDocument": {
          "Version": "2012-10-17",
          "Statement": [
            {
              "Effect": "Allow",
              "Principal": {
                "Service": [
                  "lambda.amazonaws.com"
                ]
              },
              "Action": [
                "sts:AssumeRole"
              ]
            }
          ]
        },
        "Path": "/",
        "ManagedPolicyArns": [
          "arn:aws:iam::aws:policy/service-role/AWSLambdaVPCAccessExecutionRole"
        ],
        "Policies": [
          {
            "PolicyName": "LambdaExecutionPolicy",
            "PolicyDocument": {
              "Version": "2012-10-17",
              "Statement": [
                {
                  "Effect": "Allow",
                  "Action": [
                    "lambda:PublishVersion"
                  ],
                  "Resource": [
                    "*"
                  ]
                }
              ]
            }
          }
        ]
      }
    },
    "DeploymentLambda": {
      "Type": "AWS::Lambda::Function",
      "Properties": {
        "Role": {
          "Fn::GetAtt": [
            "DeploymentLambdaRole",
            "Arn"
          ]
        },
        "Handler": "serverless.handler",
        "Runtime": "nodejs4.3",
        "Code": {
          "S3Bucket": {
            "Fn::Sub": "serverless-arch-${AWS::Region}"
          },
          "S3Key": "serverless.zip"
        }
      }
    },
    "LambdaVersion": {
      "Type": "Custom::LambdaVersion",
      "Properties": {
        "ServiceToken": {
          "Fn::GetAtt": [
            "DeploymentLambda",
            "Arn"
          ]
        },
        "FunctionName": {
          "Ref": "LambdaFunctionToBeVersioned"
        },
        "DeploymentTime": {
          "Ref": "DeploymentTime"
        }
      }
    }
  }
}

(Disclaimer: This code is a part of my book, for more information about Lambda & API Gateway you can check: https://www.amazon.com/Building-Serverless-Architectures-Cagatay-Gurturk/dp/1787129195)