serverless-api-gateway-throttling/src/updateHttpApiStageThrottling.js

A plugin for the Serverless framework which configures throttling for API Gateway endpoints.

const isEmpty = require('lodash.isempty');
const { retrieveHttpApiId } = require('./httpApiId');
const { httpApiEventOf } = require('./lib');

const updateHttpApi = async (settings, serverless) => {
    const httpApiId = await retrieveHttpApiId(serverless, settings);

    let httpApiRouteSettings = {};
    for (const httpApiEndpointSettings of settings.httpApiEndpointSettings) {
        httpApiRouteSettings = {
            ...httpApiRouteSettings,
            ...createRouteSettingsForHttpApiEndpoint(httpApiEndpointSettings, serverless),
        }
    }

    const { defaultHttpApiStage, region } = settings;

    const params = {
        ApiId: httpApiId,
        StageName: defaultHttpApiStage,
        DefaultRouteSettings: createRouteSettingsForStage(settings),
        RouteSettings: httpApiRouteSettings
    }

    serverless.cli.log(`[serverless-api-gateway-throttling] Updating API Gateway HTTP API throttling settings...`);
    await serverless.providers.aws.request('ApiGatewayV2', 'updateStage', params, { region });
    serverless.cli.log(`[serverless-api-gateway-throttling] Done updating API Gateway HTTP API throttling settings.`);
}

const createRouteSettingsForStage = (settings) => {
    return {
        ThrottlingBurstLimit: settings.maxConcurrentRequests,
        ThrottlingRateLimit: settings.maxRequestsPerSecond
    }
}

const createRouteSettingsForHttpApiEndpoint = (endpointSettings, serverless) => {
    let lambda = serverless.service.getFunction(endpointSettings.functionName);
    if (isEmpty(lambda.events)) {
        serverless.cli.log(`[serverless-api-gateway-throttling] Lambda ${endpointSettings.functionName} has not defined events.`);
        return;
    }
    const httpApiEvent = httpApiEventOf(lambda, endpointSettings);
    if (isEmpty(httpApiEvent)) {
        serverless.cli.log(`[serverless-api-gateway-throttling] Lambda ${endpointSettings.functionName} has not defined any HTTP API events.`);
        return;
    }

    let { path, method } = httpApiEvent;
    //Throttling route setting should be created with the same method type as defined in the httpApi.
    return routeSettingsForMethod(path, method.toUpperCase(), endpointSettings);
}

const routeSettingsForMethod = (path, method, endpointSettings) => {
    const route = {
        [`${method.toUpperCase()} ${path}`]: {
            ThrottlingBurstLimit: endpointSettings.maxConcurrentRequests,
            ThrottlingRateLimit: endpointSettings.maxRequestsPerSecond
        }
    }
    return route;
}

module.exports = {
    updateHttpApi
}