AWS Lambda

Invoke an AWS Lambda function from IAM. It can be used in combination with other request plugins to secure, manage or extend the function.

Terminology

• plugin: a plugin executing actions inside IAM before or after a request has been proxied to the upstream API.
• Service: the IAM entity representing an external upstream API or microservice.
• Route: the IAM entity representing a way to map downstream requests to upstream services.
• Consumer: the IAM entity representing a developer or machine using the API. When using IAM, a Consumer only communicates with IAM which proxies every call to the said upstream API.
• Credential: a unique string associated with a Consumer, also referred to as an API key.
• upstream service: this refers to your own API/service sitting behind IAM, to which client requests are forwarded.

Configuration

This plugin is compatible with requests with the following protocols:

• http
• https

This plugin is compatible with DB-less mode.

Enabling the plugin on a Service

With a database

Configure this plugin on a Service by making the following request:

$ curl -X POST http://localhost:8001/services/{service}/plugins \
    --data "name=aws-lambda"  \
    --data-urlencode "config.aws_key=AWS_KEY" \
    --data-urlencode "config.aws_secret=AWS_SECRET" \
    --data "config.aws_region=AWS_REGION" \
    --data "config.function_name=LAMBDA_FUNCTION_NAME"

Without a database

Configure this plugin on a Service by adding this section do your declarative configuration file:

plugins:
- name: aws-lambda
  service: {service}
  config: 
    aws_key: AWS_KEY
    aws_secret: AWS_SECRET
    aws_region: AWS_REGION
    function_name: LAMBDA_FUNCTION_NAME

In both cases, {service} is the id or name of the Service that this plugin configuration will target.

Enabling the plugin on a Route

With a database

Configure this plugin on a Route with:

$ curl -X POST http://localhost:8001/routes/{route}/plugins \
    --data "name=aws-lambda"  \
    --data-urlencode "config.aws_key=AWS_KEY" \
    --data-urlencode "config.aws_secret=AWS_SECRET" \
    --data "config.aws_region=AWS_REGION" \
    --data "config.function_name=LAMBDA_FUNCTION_NAME"

Without a database

Configure this plugin on a Route by adding this section do your declarative configuration file:

plugins:
- name: aws-lambda
  route: {route}
  config: 
    aws_key: AWS_KEY
    aws_secret: AWS_SECRET
    aws_region: AWS_REGION
    function_name: LAMBDA_FUNCTION_NAME

In both cases, {route} is the id or name of the Route that this plugin configuration will target.

Enabling the plugin on a Consumer

With a database

You can use the http://localhost:8001/plugins endpoint to enable this plugin on specific Consumers:

$ curl -X POST http://localhost:8001/consumers/{consumer}/plugins \
    --data "name=aws-lambda" \
     \
    --data-urlencode "config.aws_key=AWS_KEY" \
    --data-urlencode "config.aws_secret=AWS_SECRET" \
    --data "config.aws_region=AWS_REGION" \
    --data "config.function_name=LAMBDA_FUNCTION_NAME"

Without a database

Configure this plugin on a Consumer by adding this section do your declarative configuration file:

plugins:
- name: aws-lambda
  consumer: {consumer}
  config: 
    aws_key: AWS_KEY
    aws_secret: AWS_SECRET
    aws_region: AWS_REGION
    function_name: LAMBDA_FUNCTION_NAME

In both cases, {consumer} is the id or username of the Consumer that this plugin configuration will target.

You can combine consumer_id and service_id

in the same request, to furthermore narrow the scope of the plugin.

Global plugins

• Using a database, all plugins can be configured using the http://localhost:8001/plugins/ endpoint.
• Without a database, all plugins can be configured via the plugins: entry on the declarative configuration file.

A plugin which is not associated to any Service, Route or Consumer (or API, if you are using an older version of IAM) is considered "global", and will be run on every request. Read the Plugin Reference and the Plugin Precedence sections for more information.

Parameters

Here's a list of all the parameters which can be used in this plugin's configuration:

Reminder: curl by default sends payloads with an application/x-www-form-urlencoded MIME type, which will naturally be URL- decoded by IAM. To ensure special characters that are likely to appear in your AWS key or secret (like +) are correctly decoded, you must URL-encode them, hence use --data-urlencode if you are using curl. Alternatives to this approach would be to send your payload with a different MIME type (like application/json), or to use a different HTTP client.

Sending parameters

Any form parameter sent along with the request, will be also sent as an argument to the AWS Lambda function.

Known Issues

Use a fake upstream service

When using the AWS Lambda plugin, the response will be returned by the plugin itself without proxying the request to any upstream service. This means that a Service's host, port, path properties will be ignored, but must still be specified for the entity to be validated by IAM. The host property in particular must either be an IP address, or a hostname that gets resolved by your nameserver.

Response plugins

There is a known limitation in the system that prevents some response plugins from being executed. We are planning to remove this limitation in the future.

Step By Step Guide

The Steps

1. Access to AWS Console as user allowed to operate with lambda functions and create user and roles.
2. Create an Execution role in AWS
3. Create an user which will be invoke the function via IAM, test it.
4. Create a Service & Route in IAM, add the aws-lambda plugin linked to our aws function and execute it.

Configure

1. First, let's create an execution role called LambdaExecutor for our lambda function.

   In IAM Console create a new Role choosing the AWS Lambda service, there will be no policies as our function in this example will simply execute itself giving us back an hardcoded JSON as response without accessing other AWS resources.

2. Now let's create a user named IAMInvoker, used by our IAM API gateway to invoke the function.

   In IAM Console create a new user, must be provided to it programmatic access via Access and Secret keys; then will attach existing policies directly particularly the AWSLambdaRole predefined. Once the user creation is confirmed, store Access Key and Secret Key in a safe place.

3. Now we need to create the lambda function itself, will do so in N.Virginia Region (code us-east-1).

   In Lambda Management, create a new function Mylambda, there will be no blueprint as we are going to paste the code below; for the execution role let's choose an existing role specifically LambdaExecutor created previously

   Use the inline code below to have a simple JSON response in return, note this is code for Python 3.6 interpreter.

    import json
    def lambda_handler(event, context):
        """
          If is_proxy_integration is set to true :
          jsonbody='''{"statusCode": 200, "body": {"response": "yes"}}'''
        """
        jsonbody='''{"response": "yes"}'''
        return json.loads(jsonbody)
   

   Test the lambda function from the AWS console and make sure the execution succeeds.

4. Finally we setup a Service & Route in IAM and link it to the function just created.

With a database

curl -i -X POST http://{kong_hostname}:8001/services \
--data 'name=lambda1' \
--data 'url=http://localhost:8000' \

The Service doesn't really need a real url since we are not going to have an HTTP call to upstream but rather a response generated by our function.

Also create a Route for the Service:

curl -i -X POST http://{kong_hostname}:8001/services/lambda1/routes \
--data 'paths[1]=/lambda1'

Add the plugin:

curl -i -X POST http://{kong_hostname}:8001/services/lambda1/plugins \
--data 'name=aws-lambda' \
--data-urlencode 'config.aws_key={IAMInvoker user key}' \
--data-urlencode 'config.aws_secret={IAMInvoker user secret}' \
--data 'config.aws_region=us-east-1' \
--data 'config.function_name=MyLambda'

Without a database

Add a Service, Route and Plugin to the declarative config file:

services:
- name: lambda1
  url: http://localhost:8000

routes:
- service: lambda1
  paths: [ "/lambda1" ]

plugins:
- service: lambda1
  name: aws-lambda
  config:
    aws_key: {IAMInvoker user key}
    aws_secret: {IAMInvoker user secret}
    aws_region: us-east-1
    function_name: MyLambda

Once everything is created, call the Service and verify the correct invocation, execution and response:

curl http://{kong_hostname}:8000/lambda1

Additional headers:

x-amzn-Remapped-Content-Length, X-Amzn-Trace-Id, x-amzn-RequestId

JSON response:

{"response": "yes"}

Have fun leveraging the power of AWS Lambda in IAM!