aws-lambda-server

description

A server which invokes AWS lambda functions from http requests, mapping the request to the payload.

docker image

A docker image can be found at ghcr.io/tanemahuta/aws-lambda-server:<tag>.

routing

Routing is achieved using gorilla/mux.

When using a path in the request route, you may use path variables (e.g. /test/{id}), which will be parsed and propagated to the lambda invocation.

function invocation

The AWS lambda function is invoked using the aws-sdk.

If you need to attach an IAM role in an EKS cluster, check out this article.

request

The parsed request is being adapted using aws.LambdaRequest.

To handle the request, you can use the first parameter in your handler:

async function handler(req, ctx) {
    console.log("hostname", req.host);
    console.log("headers", req.headers);
    console.log("method", req.method);
    console.log("full uri", req.uri);
    console.log("parsed path variables", req.vars);
    console.log("read body", req.body);
}

response

The returned response is being adapted using aws.LambdaResponse.

An example response may look like this:

async function handler(req, ctx) {
    return {
        statusCode: 200,
        headers: {
            "Content-Type": "text/plain"
        },
        body: "Hello world"
    }
}

Alternatively the body may be a JSON, which will be serialized by the server:

async function handler(req, ctx) {
    return {
        statusCode: 200,
        headers: {
            "Content-Type": "application/json"
        },
        body: {
            "Hello": "World"
        }
    }
}

which will result in a {"Hello":"World"} in the server's HTTP response body.

command-line args

When running the binary, the following command line parameters can be used:

• --devel=(true|false): run in development mode (logging)
• --config-file=<path>: use the provided config file (default: /etc/aws-lambda-server/config.yaml)
• --listen=<addr>: use the provided listen address (default: :8080) for serving the requests towards the lambda
• --metrics-listen=<addr>: use the provided listen address (default: :8081) for serving metrics/health/readiness checks

configuration

The configuration adds request matchers to a function. For the schema, start here

An annotated example config can be found here.

metrics, healthz and readyz

The application provides health (/healthz) and readiness checks (/readyz) listening to the configured --metrics-listen address.

Additionally, the following metrics are available:

• http_requests_total: counter for total http requests served
• http_request_duration_seconds: histogram for http request duration
• http_request_size_bytes: histogram for http request size
• http_response_size_bytes: histogram for http response size
• aws_lambda_invocation_total: counter for AWS lambda invocations by function ARN
• aws_lambda_invocation_errors_total: gauge for AWS lambda invocation errors by function ARN
• aws_lambda_invocation_duration_seconds: histogram AWS lambda invocation duration by function ARN

helm-chart

Helm charts are created from the charts directory and published to this repository.