Simple demo for a microservice serverless deploy in AWS Lambda

Very simple use case for this example. A request that returns current weather for a city.

Once the request is executed using the key cityName like in the following example:

{
  "cityName": "london",
}

Service will invoke a public API endpoint that response with data about current time based on city criteria in JSON format.

Related to deployment this project uses serverless platform. You can take a look on this platform and further information in serverless web page

In that case is very important to fulfill properly file serverless.yml. Take a look in functions properties:

functions:
  request:
    handler: org.pedrograciabernal.serverless.simple.function.AwsLambdaHandler
    environment:
      FUNCTION_NAME: city
      RESOURCE_URL: "https://weatherdbi.herokuapp.com/"
      RESOURCE_CONTEXT: "data/weather/"

It is mandatory to set complete package path value pointing to class AwsLambdaHandler in order than AWS Lambda has an starting point.

Take a look as well to the environment variables block:

• FUNCTION_NAME: point to the endpoint context that matches with the name of the method who receives the request.
• RESOURCE_URL: information with the public API url used by the service to send the request about weather in a city.
• RESOURCE_CONTEXT: context into endpoint to address API request.

All these variables will be send to AWS Lambda as Environment variables into Configuration tab lambda information deployed:

Once you check code, and after install serverless bundle in your local machine, execute serverless from a command line. You will have a very similar response like this (maybe region is differente to us-east-1):

Deploying aws-spring-cloud-function-city to stage dev (us-east-1)

✔ Service deployed to stack aws-spring-cloud-function-city-dev (51s)

endpoint: GET - https://xxxxx.execute-api.us-east-1.amazonaws.com/city
functions:
  request: aws-spring-cloud-function-city-dev-request (14 MB)

Really serverless platform has proceed to execute some tasks using CloudFormation feature from AWS, creating an API Gateway and deployment this project into AWS Lambda

Once serverless has finished succesfully you can visit your aws console and go to AWS Lambda service. You will see the new function in the grid, just click on its name and, once in the Function overview, select Test tab.

Check New event option and set the following json format message into the text area:

{
  "cityName": "london",
}

And finally click on Test button:

After a few seconds, into Execution result section you must check a succesfull answer very similar to this one:

{
  "cityName": "london",
  "weather": {
    "region": "London, UK",
    "currentConditions": {
      "dayhour": "Friday 1:00 PM",
      "temp": {
        "celsius": "12",
        "fahrenheit": "53"
      },
      "precipitation": "85%",
      "humidity": "73%",
      "comment": "Cloudy",
      "wind": {
        "km": "19",
        "mile": "12"
      }
    }
  }
}

Like this project uses serverless platform, you can check what deployment file has been configured by this platform into CloudFormation services for AWS