README.md

Multi-instance Serverless AWS Lambda function example

This example demonstrates how to deploy multiple instances (or copies) of the same lambda function by using the "--param" sls option to pass in an instance name. The main idea is to rename AWS resources and outputs which would otherwise clash using the instance name.

A lambda instance's configuration can then be made instance-specific by adding the instance name to its environment variable or parameter store keys.

The benefit of this approach is that only one lambda function needs to be defined in serverless.ts (or serverless.yml), but any number of copies of it can be deployed directly from the command line.

Setup

1. Install Node.js 18 (recommended: Node Version Manager).

2. Install packages:

   npm i

Use case

When you want to deploy multiple lambda functions with the same implementation, but you don't want to explicitly define each copy in serverless.yml.

For example, you could deploy the lambda copies in a continuous deployment (CD) pipeline and configure them to fetch data from different sources based on their instance names.

Usage

Deployment

To deploy an instance "foo" of the lambda hello to the default dev stage in the ap-southeast-2 region , run:

npx sls deploy --region ap-southeast-2 --param="instance=foo"

Another instance, "bar", can be deployed with:

npx sls deploy --region ap-southeast-2 --param="instance=bar"

Now, two separate yet identical hello lambdas are available on AWS:

Note that the "--param" option is now required when running other serverless commands, such as sls info:

npx sls info --region ap-southeast-2 --param="instance=foo"

Invocation

To invoke an instance of hello using sls invoke, pass the instance name to the "--param" option:

npx sls invoke -f hello --region ap-southeast-2 --param="instance=foo"

Output:

{
    "statusCode": 200,
    "body": "{\n  \"message\": \"Function `aws-node-typescript-multi-instance-lambda-foo-dev-hello` executed successfully.\",\n  \"input\": {}\n}"
}

Removal

"--param" is also required to run the sls remove command to tear down the CloudFormation stack associated with a specific instance.

npx sls remove --region ap-southeast-2 --param="instance=foo"

Acknowledgements

• This comment by @rdemorais on Serverless issue #9361.
• @billkidwell's Simple Kinesis Example.