Simple HTTP Endpoint Example

This example demonstrates how to setup a simple HTTP GET endpoint. Once you fetch it, it will reply with the current time. While the internal function is name currentTime the HTTP endpoint is exposed as time.

Use Cases

  • Wrapping an existing internal or external endpoint/service

Invoke the function locally

serverless invoke local --function currentTime

Which should result in:

Serverless: Your function ran successfully.
{
    "statusCode": 200,
    "body": "{\"message\":\"Hello, the current time is 12:49:06 GMT+0100 (CET).\"}"
}

Deploy

In order to deploy the endpoint, simply run:

serverless deploy

The expected result should be similar to:

Serverless: Packaging service…
Serverless: Uploading CloudFormation file to S3…
Serverless: Uploading service .zip file to S3…
Serverless: Updating Stack…
Serverless: Checking Stack update progress…
...........................
Serverless: Stack update finished…
Service Information
service: serverless-simple-http-endpoint
stage: dev
region: us-east-1
api keys:
  None
endpoints:
  GET - https://2e16njizla.execute-api.us-east-1.amazonaws.com/time
functions:
  serverless-simple-http-endpoint-dev-currentTime: arn:aws:lambda:us-east-1:488110005556:function:serverless-simple-http-endpoint-dev-currentTime

Usage

You can now invoke the Lambda directly and even see the resulting log via

serverless invoke --function currentTime --log

or as send an HTTP request directly to the endpoint using a tool like curl

curl https://XXXXXXX.execute-api.us-east-1.amazonaws.com/time

Scaling

By default, AWS Lambda limits the total concurrent executions across all functions within a given region to 1000. The default limit is a safety limit that protects you from costs due to potential runaway or recursive functions during initial development and testing. To increase this limit above the default, follow the steps in To request a limit increase for concurrent executions.