{"id":1081,"date":"2021-07-24T07:40:01","date_gmt":"2021-07-24T14:40:01","guid":{"rendered":"https:\/\/bullyrooks.com\/?p=1081"},"modified":"2021-07-25T06:53:39","modified_gmt":"2021-07-25T13:53:39","slug":"spring-boot-lambda-api-implementation","status":"publish","type":"post","link":"https:\/\/bullyrooks.com\/index.php\/2021\/07\/24\/spring-boot-lambda-api-implementation\/","title":{"rendered":"Spring Boot Lambda API Implementation"},"content":{"rendered":"\n
We’ve got a ‘working’ lambda now, but we can’t actually use it anywhere. The easiest thing to do at this point is add an API Gateway trigger to our function as a new lambda. This will require a little bit of work to make an API Gateway adapter to our service and then add the API Gateway trigger.<\/p>\n\n\n\n
Start a New Branch<\/h2>\n\n\n\n
$ git checkout -b apifunction\nSwitched to a new branch 'apifunction'\n<\/code><\/pre>\n\n\n\n
Create an API Gateway Function<\/h2>\n\n\n\n
in our function<\/code> directory make a new class HelloWorldAPIFunction<\/code><\/p>\n\n\n\n
The API Gateway adapter operates on Message<\/code> objects which will contain JSON serializable messages. We’re going to use HelloWorldRequest<\/code> and HelloWorldResponse<\/code> as DTO to serialize the request and response. The rest of this function just transforms the DTO and makes the service call and transforms the response back. There is a little bit of trickiness in that the Message<\/code> headers will contain the HTTP information that we’ll use in the API Gateway (i.e. statuscode). However, this is exactly inline with our ports and adapters design mindset. <\/p>\n\n\n\n
Finally, we need to explicitly define the bean so that the SpringBootApiGatewayRequestHandler<\/code> can find it. Add these lines to the HelloworldLambdaApplication <\/code>class<\/p>\n\n\n\n
@Bean\n HelloWorldAPIFunction apiFunction() {\n return new HelloWorldAPIFunction();\n }<\/code><\/pre>\n\n\n\n
That should be it. Lets build the jar<\/p>\n\n\n\n
We’re going to create the lambda the exact same way with a few minor changes. <\/p>\n\n\n\n
The handler will be org.springframework.cloud.function.adapter.aws.SpringBootApiGatewayRequestHandler::handleRequest<\/code> and the environment variable FUNCTION_NAME<\/code> will change to apiFunction<\/code><\/p>\n\n\n\n<\/figure>\n\n\n\n
Add the API Gateway Trigger<\/h2>\n\n\n\n
On the function overview page, click Add trigger<\/code><\/p>\n\n\n\n<\/figure>\n\n\n\n
From the drop down choose API Gateway<\/code><\/p>\n\n\n\n<\/figure>\n\n\n\n
Choose Create an API<\/code>, HTTP API<\/code> and Open<\/code> security. Then hit Add<\/code><\/p>\n\n\n\n<\/figure>\n\n\n\n
You should see a green box that says the trigger was added<\/p>\n\n\n\n<\/figure>\n\n\n\n
Testing the Lambda<\/h2>\n\n\n\n
You won’t be able to use the Test<\/code> tab here. The lambda is now expecting a Message<\/code> object, which you probably don’t want to have to create (although there are templates for it). Instead we’re going to test via Postman (or whatever HTTP tool you prefer).<\/p>\n\n\n\n
Go to the API Gateway trigger and navigate to the details page to find the URL that the API Gateway is exposing the lambda as.<\/p>\n\n\n\n
Click on API Gateway<\/p>\n\n\n\n<\/figure>\n\n\n\n
Open up the Details<\/code> section and copy out the URL for the API endpoint<\/p>\n\n\n\n<\/figure>\n\n\n\n
Paste it into postman and make a body for our request:<\/p>\n\n\n\n
You should see a successful response.<\/p>\n\n\n\n
That’s it for now. However, creating all of these objects in AWS manually is tedious and prone to risk. In the next sections I’ll show you how to automate the deployment via Terraform.<\/p>\n\n\n\n
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