204 lines
7.6 KiB
Markdown
204 lines
7.6 KiB
Markdown
---
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layout: pattern
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title: Serverless
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folder: serverless
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permalink: /patterns/serverless/
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categories: Architectural
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tags:
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- Cloud distributed
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---
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## Serverless
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Serverless eliminates the need to plan for infrastructure and let's you focus on your
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application.
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Following are optimization katas you should be aware of while building a serverless
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applications
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* The Lean function
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* Concise logic - Use functions to transform, not transport (utilize some of the
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integration available from the provider to transport), and make sure you read only
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what you need
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* Efficient/single purpose code - avoid conditional/routing logic and break down
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into individual functions, avoid "fat"/monolithic functions and control the
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dependencies in the function deployment package to reduce the load time for your
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function
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* ephemeral environment - Utilize container start for expensive initializations
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* Eventful Invocations
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* Succinct payloads - Scrutinize the event as much as possible, and watch for
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payload constraints (async - 128K)
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* resilient routing - Understand retry policies and leverage dead letter queues
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(SQS or SNS for replays) and remember retries count as invocations
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* concurrent execution - lambda thinks of it's scale in terms of concurrency and
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its not request based/duration based. Lambda will spin up the number of instances
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based on the request.
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* Coordinated calls
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* Decoupled via APIs - best practice to setup your application is to have API's as
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contracts that ensures separation of concerns
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* scale-matched downstream - make sure when Lambda is calling downstream
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components, you are matching scale configuration to it (by specifying max
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concurrency based on downstream services)
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* secured - Always ask a question, do I need a VPC?
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* Serviceful operations
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* Automated - use automated tools to manage and maintain the stack
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* monitored applications - use monitoring services to get holistic view of your
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serverless applications
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## Intent
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Whether to reduce your infrastructure costs, shrink the time you spend on ops tasks,
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simplify your deployment processes, reach infinite scalability, serverless cuts time
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to market in half.
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## Explanation
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Serverless computing is a cloud computing execution model in which the cloud provider
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dynamically manages the allocation of machine resources. Pricing is based on the
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actual amount of resources consumed by an application, rather than on pre-purchased
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units of capacity.
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## Class diagram
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## Serverless framework
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[Serverless](https://serverless.com/) is a toolkit for deploying and operating serverless architectures.
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## (Function as a Service or "FaaS")
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The term ‘Serverless’ is confusing since with such applications there are both server
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hardware and server processes running somewhere, but the difference to normal
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approaches is that the organization building and supporting a ‘Serverless’ application
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is not looking after the hardware or the processes - they are outsourcing this to a vendor.
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Some of the Serverless Cloud Providers are
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...
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Anything that triggers an Lambda Function to execute is regarded by the Framework as
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an Event. Most of the Serverless Cloud Providers support following Events
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- Http
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- PubSub Events
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- scheduled
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AWS supports processing event generated from AWS Services (S3/Cloudwatch/etc) and
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using aws as a compute engine is our first choice.
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## (Backend as a Service or "BaaS")
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This example creates a backend for ‘persons’ collection which uses DynamoDB NoSQL
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database service also provided by Amazon.
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## AWS lambda function implementation
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[AWS Lambda SDK](https://aws.amazon.com/sdk-for-java/) provides pre-defined interface
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`com.amazonaws.services.lambda.runtime
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.RequestHandler` to implement our lambda function.
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```java
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public class LambdaInfoApiHandler implements RequestHandler<Map<String, Object>, ApiGatewayResponse> {
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private static final Logger LOG = Logger.getLogger(LambdaInfoApiHandler.class);
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private static final Integer SUCCESS_STATUS_CODE = 200;
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@Override
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public ApiGatewayResponse handleRequest(Map<String, Object> input, Context context) {
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}
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}
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```
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handleRequest method is where the function code is implemented. Context provides
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useful information about Lambda execution environment. AWS Lambda function needs a
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deployment package. This package is either a .zip or .jar file that contains all the
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dependencies of the function.
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`serverless.yml` contains configuration to manage deployments for your functions.
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## Run example in local
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# Pre-requisites
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* Node.js v6.5.0 or later.
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* Serverless CLI v1.9.0 or later. You can run npm install -g serverless to install it.
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* An AWS account. If you don't already have one, you can sign up for a free trial that includes 1 million free Lambda requests per month.
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* [Set-up](https://serverless.com/framework/docs/providers/aws/guide/credentials/) your Provider Credentials. Watch the video on setting up credentials
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# build and deploy
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* `cd serverless`
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* `mvn clean package`
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* `serverless deploy --stage=dev --verbose`
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Based on the configuration in `serverless.yml` serverless framework creates following
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resources
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* CloudFormation stack for S3 (ServerlessDeploymentBucket)
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* IAM Role (IamRoleLambdaExecution)
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* CloudWatch (log groups)
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* API Gateway (ApiGatewayRestApi)
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* Lambda function
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* DynamoDB collection
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The command will print out Stack Outputs which looks something like this
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```yaml
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endpoints:
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GET - https://xxxxxxxxx.execute-api.us-east-1.amazonaws.com/dev/info
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POST - https://xxxxxxxxx.execute-api.us-east-1.amazonaws.com/dev/api/person
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GET - https://xxxxxxxxx.execute-api.us-east-1.amazonaws.com/dev/api/person/{id}
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```
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```yaml
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CurrentTimeLambdaFunctionQualifiedArn: arn:aws:lambda:us-east-1:xxxxxxxxxxx:function:lambda-info-http-endpoint-dev-currentTime:4
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ServiceEndpoint: https://xxxxxxxxx.execute-api.us-east-1.amazonaws.com/dev
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ServerlessDeploymentBucketName: lambda-info-http-endpoin-serverlessdeploymentbuck-2u8uz2i7cap2
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```
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access the endpoint to invoke the function.
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Use the following cURL commands to test the endpoints
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```cURL
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curl -X GET \
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https://xxxxxxxxx.execute-api.us-east-1.amazonaws.com/dev/info \
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-H 'cache-control: no-cache'
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```
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```cURL
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curl -X POST \
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https://xxxxxxxxx.execute-api.us-east-1.amazonaws.com/dev/api/person \
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-H 'cache-control: no-cache' \
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-H 'content-type: application/json' \
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-d '{
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"firstName": "Thor",
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"lastName": "Odinson",
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"address": {
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"addressLineOne": "1 Odin ln",
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"addressLineTwo": "100",
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"city": "Asgard",
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"state": "country of the Gods",
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"zipCode": "00001"
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}
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}'
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```
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```cURL
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curl -X GET \
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https://xxxxxxxxx.execute-api.us-east-1.amazonaws.com/dev/api/person/{id} \
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-H 'cache-control: no-cache'
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```
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## Credits
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* [serverless docs](https://serverless.com/framework/docs/)
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* [Serverless Architectures](https://martinfowler.com/articles/serverless.html)
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* [Serverless Black Belt](https://youtu.be/oQFORsso2go)
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