# Serverless

Serverless (opens new window) is a free and open-source web framework written using Node.js. Serverless is the first framework developed for building applications on AWS Lambda, a serverless computing platform provided by Amazon as a part of Amazon Web Services. This tutorial will show you how to install and use Serverless with Ts.ED.

# Installation

See the Platform Serverless to install the required packages to develop your AWS Lambda functions.

# Create your first lambda

In the src/lambda create a new Lambda class:

import {Controller, Inject} from "@tsed/di";
import {Get, Returns, Summary} from "@tsed/schema";
import {QueryParams} from "@tsed/platform-params"; // /!\ don't import decorators from @tsed/common
import {TimeslotsService} from "../services/TimeslotsService";
import {TimeslotModel} from "../models/TimeslotModel";

@Controller("/timeslots")
export class TimeslotsLambda {
  @Inject()
  protected timeslotsService: TimeslotsService;

  @Get("/")
  @Summary("Return a list of timeslots")
  @Returns(200, Array).Of(TimeslotModel)
  get(@QueryParams("date_start") dateStart: Date, @QueryParams("date_end") dateEnd: Date) {
    return this.timeslotsService.find({
      dateStart,
      dateEnd
    });
  }
}

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Create new handler.ts to expose your lambda:

import {PlatformServerless} from "@tsed/serverless";
import {TimeslotsLambda} from "./lambda/TimeslotsLambda";

const platform = PlatformServerless.bootstrap({
  lambda: [TimeslotsLambda]
  // put your Application configuration here
});

// then export the lambda
const {getTimeslot} = platform.callbacks(); // build all handlers of TimeslotsLambda

export {getTimeslot};

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TIP

Since v7.66.0, you can use the PlatformServerless.callback(TimeslotsLambda, 'get') method to build and get the lambda handler.

import {PlatformServerless} from "@tsed/serverless";

export const getTimeslots = PlatformServerless.callback(TimeslotsLambda, "get", {
  // extra options
});

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This method doesn't use the find-my-way router and is faster than the handler method.

Finally, create the serverless.yml:

service: timeslots

frameworkVersion: "3.21.0"

provider:
  name: aws
  runtime: nodejs14.x
  lambdaHashingVersion: "20201221"

plugins:
  - serverless-offline

functions:
  timeslots:
    handler: dist/handler.getTimeslots
    events:
      - http:
          path: /timeslots
          method: get

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# Invoke a lambda with serverless

Serverless provide a plugin named serverless-offline. This Serverless plugin emulates AWS λ and API Gateway on your local machine to speed up your development cycles. To do so, it starts an HTTP server that handles the request's lifecycle like APIG does and invokes your handlers.

So, by using the serverless offline command, we'll be able to invoke our function. For that, we need also to build our code before invoke the lambda.

To simplify our workflow, we can add the following npm script command in our package.json:

{
  "scripts": {
    "invoke:timeslots": "yarn build && serverless invoke local -f timeslots"
  }
}

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Now, we can run the following command to invoke our lambda:

yarn invoke:timeslots
// OR
npm run invoke:timeslots

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You should see in the terminal the following result:

{
  "statusCode": 200,
  "body": "[{\"id\":\"b6de4fc7-faaa-4cd7-a144-42f6af0dec6b\",\"title\":\"title\",\"description\":\"description\",\"start_date\":\"2021-10-29T10:40:57.019Z\",\"end_date\":\"2021-10-29T10:40:57.019Z\",\"created_at\":\"2021-10-29T10:40:57.019Z\",\"update_at\":\"2021-10-29T10:40:57.019Z\"}]",
  "headers": {
    "content-type": "application/json",
    "x-request-id": "ebb52d5e-113b-40da-b34e-c14811df596b"
  },
  "isBase64Encoded": false
}

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# Manage routes from code

Declaring all routes in the serverless.yml file can be a source of error. @tsed/platform-serverless can handle all routes and call the right lambda based on the decorators like Get , Post , etc...

To use the embed router, change the serverless.yml declaration by this example:

service: timeslots

frameworkVersion: "2"

provider:
  name: aws
  runtime: nodejs14.x
  lambdaHashingVersion: "20201221"

plugins:
  - serverless-offline

functions:
  any:
    handler: dist/handler.handler
    events:
      - http:
          method: ANY
          path: /
      - http:
          method: ANY
          path: "{proxy+}"

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Then, edit the handler.ts and change the exported functions:

import {PlatformServerless} from "@tsed/platform-serverless";
import {TimeslotsLambda} from "./TimeslotsLambda";

const platform = PlatformServerless.bootstrap({
  lambda: [TimeslotsLambda]
});

export const handler = platform.handler();

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Now, Ts.ED will handle request and call the expected lambda in your controllers.

To simplify our workflow, we can add the following npm script command in our package.json:

{
  "scripts": {
    "invoke:any": "yarn serverless invoke local -f any --data '{\"path\":\"/timeslots\", \"httpMethod\": \"GET\"}'"
  }
}

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# Author

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# Serverless

# Installation

# Create your first lambda

# Invoke a lambda with serverless

# Manage routes from code

# Author

# Maintainers Help wanted

Other topics