Setting up canary deployment 

Once the initial setup is complete, we will tell the serverless canary deployment plugin to split the traffic between the last two versions and gradually shift more traffic to the new version until it receives all the load. 

The following are the three types of gradual deployment that we can implement using AWS's CodeDeploy: 

• Canary: The traffic is shifted to a new version during a certain period of time, and when the time elapses, all the traffic will have moved to the newer version
• Linear: The traffic is shifted to the new version incrementally at intervals until it gets all of the traffic
• All at once: All the traffic is shifted to the new version at once

We need to be specific as to which parameter and type of deployment we will use by choosing any of the aforementioned options for using CodeDeploy:

Canary10Percent30Minutes, Canary10Percent5Minutes, Canary10Percent10Minutes, Canary10Percent15Minutes, Linear10PercentEvery10Minutes, Linear10PercentEvery1Minute, Linear10PercentEvery2Minutes, Linear10PercentEvery3Minutes or AllAtOnce.

For our tutorial, we will use Linear10PercentEvery1Minute, which means that the traffic that the new version of the function will receive will be increased by 10 percent increments every minute, until it reaches 100%. To do this, we need to set the type and alias (the name of the alias that we want to create) under deploymentSettings in the function. Let's update the files, and redeploy and invoke the function to see how the traffic moves: 

1. Add the deployment settings within the serverless.yml, as shown in the following code: 

service: my-canary-deployment
provider:
 name: aws
 runtime: nodejs6.10

plugins:
 - serverless-plugin-canary-deployments
functions:
 hello:
     handler: handler.hello
     events:
         - http: get hello
     deploymentSettings:
         type: Linear10PercentEvery1Minute
         alias: Live

2. Update the handler.js with the following code: 

module.exports.hello = (event, context, callback) => {
    const response = {
    statusCode: 200,
    body: 'Hey new version is 1.26.1 !'
    };
    callback(null, response);
};

3. Let's deploy the function. You will see from the following code that the deployment will trigger CodeDeploy with linear deployment, and requests will be load balanced between the two functions: 

$ serverless deploy -v

Serverless: Packaging service...
---
Serverless: Checking Stack update progress...
CloudFormation - UPDATE_IN_PROGRESS - AWS::CloudFormation::Stack - my-canary-deployment-dev
CloudFormation - CREATE_IN_PROGRESS - AWS::IAM::Role - CodeDeployServiceRole
CloudFormation - CREATE_IN_PROGRESS - AWS::CodeDeploy::Application - MycanarydeploymentdevDeploymentApplication
CloudFormation - UPDATE_IN_PROGRESS - AWS::Lambda::Function - HelloLambdaFunction
CloudFormation - CREATE_IN_PROGRESS - AWS::CodeDeploy::Application - MycanarydeploymentdevDeploymentApplication
CloudFormation - CREATE_IN_PROGRESS - AWS::IAM::Role - CodeDeployServiceRole
CloudFormation - CREATE_COMPLETE - AWS::CodeDeploy::Application - MycanarydeploymentdevDeploymentApplication
CloudFormation - UPDATE_COMPLETE - AWS::Lambda::Function - HelloLambdaFunction
CloudFormation - CREATE_IN_PROGRESS - AWS::Lambda::Version - HelloLambdaVersionW59z2S8rIu6lAv3dCyvgKLndpEosDs1l1kpbg6Lrg
CloudFormation - CREATE_IN_PROGRESS - AWS::Lambda::Version - HelloLambdaVersionW59z2S8rIu6lAv3dCyvgKLndpEosDs1l1kpbg6Lrg
CloudFormation - CREATE_COMPLETE - AWS::Lambda::Version - HelloLambdaVersionW59z2S8rIu6lAv3dCyvgKLndpEosDs1l1kpbg6Lrg
CloudFormation - CREATE_COMPLETE - AWS::IAM::Role - CodeDeployServiceRole
CloudFormation - CREATE_IN_PROGRESS - AWS::CodeDeploy::DeploymentGroup - HelloLambdaFunctionDeploymentGroup
CloudFormation - CREATE_IN_PROGRESS - AWS::CodeDeploy::DeploymentGroup - HelloLambdaFunctionDeploymentGroup
CloudFormation - CREATE_COMPLETE - AWS::CodeDeploy::DeploymentGroup - HelloLambdaFunctionDeploymentGroup
CloudFormation - CREATE_IN_PROGRESS - AWS::Lambda::Alias - HelloLambdaFunctionAliasLive
CloudFormation - CREATE_IN_PROGRESS - AWS::Lambda::Alias - HelloLambdaFunctionAliasLive
CloudFormation - CREATE_COMPLETE - AWS::Lambda::Alias - HelloLambdaFunctionAliasLive
CloudFormation - UPDATE_IN_PROGRESS - AWS::ApiGateway::Method - ApiGatewayMethodHelloGet
CloudFormation - UPDATE_COMPLETE - AWS::ApiGateway::Method - ApiGatewayMethodHelloGet
CloudFormation - UPDATE_IN_PROGRESS - AWS::Lambda::Permission - HelloLambdaPermissionApiGateway
CloudFormation - UPDATE_IN_PROGRESS - AWS::Lambda::Permission - HelloLambdaPermissionApiGateway
CloudFormation - CREATE_IN_PROGRESS - AWS::ApiGateway::Deployment - ApiGatewayDeployment1530401347906
CloudFormation - CREATE_IN_PROGRESS - AWS::ApiGateway::Deployment - ApiGatewayDeployment1530401347906
CloudFormation - CREATE_COMPLETE - AWS::ApiGateway::Deployment - ApiGatewayDeployment1530401347906
CloudFormation - UPDATE_COMPLETE - AWS::Lambda::Permission - HelloLambdaPermissionApiGateway
CloudFormation - UPDATE_COMPLETE_CLEANUP_IN_PROGRESS - AWS::CloudFormation::Stack - my-canary-deployment-dev
CloudFormation - DELETE_IN_PROGRESS - AWS::Lambda::Permission - HelloLambdaPermissionApiGateway
CloudFormation - DELETE_IN_PROGRESS - AWS::ApiGateway::Deployment - ApiGatewayDeployment1530398711004
CloudFormation - DELETE_SKIPPED - AWS::Lambda::Version - HelloLambdaVersionjAYLrhwIiK3mGoae1oyrqMYfnXsHGIk0IuE6gh2dWdA
CloudFormation - DELETE_COMPLETE - AWS::ApiGateway::Deployment - ApiGatewayDeployment1530398711004
CloudFormation - DELETE_COMPLETE - AWS::Lambda::Permission - HelloLambdaPermissionApiGateway
CloudFormation - UPDATE_COMPLETE - AWS::CloudFormation::Stack - my-canary-deployment-dev

4. Let's invoke the function and see whether it is load balanced, as shown in the following code: 

$ curl https://<api-gateway-path>.amazonaws.com/dev/hello
Go Serverless v1.0! Your function executed successfully!

$ curl https://<api-gateway-path>.amazonaws.com/dev/hello
Hey new version is 1.26.1!