122 lines
4.6 KiB
Markdown
122 lines
4.6 KiB
Markdown
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---
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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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- Java
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- Difficulty-Intermittent
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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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## 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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## 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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## AWS lambda function implementation
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AWS lambda SDK provides pre-defined interface `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 a
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cloud formation stack for S3 (ServerlessDeploymentBucket), IAM Role
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(IamRoleLambdaExecution), cloud watch (log groups), API Gateway (ApiGatewayRestApi)
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and the Lambda function.
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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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```
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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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## 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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