Nest application example

This example demonstrates how to setup a Nest application.

Use Cases

Running the app locally

npm start

Which should result in:

$ sls offline start
Serverless: Compiling with Typescript...
Serverless: Using local tsconfig.json
Serverless: Typescript compiled.
Serverless: Watching typescript files...
Serverless: Starting Offline: dev/us-east-1.
Serverless: Routes for main:
Serverless: ANY /{proxy*}
Serverless: Offline listening on http://localhost:3000

Then browse http://localhost:3000/hello

The logs should be :

Serverless: ANY /hello (λ: main)
[Nest] 7956   - 2018-12-13 10:34:22   [NestFactory] Starting Nest application... +6933ms
[Nest] 7956   - 2018-12-13 10:34:22   [InstanceLoader] AppModule dependencies initialized +4ms
[Nest] 7956   - 2018-12-13 10:34:22   [RoutesResolver] AppController {/}: +2ms
[Nest] 7956   - 2018-12-13 10:34:22   [RouterExplorer] Mapped {/hello, GET} route +1ms
[Nest] 7956   - 2018-12-13 10:34:22   [NestApplication] Nest application successfully started +1ms
Serverless: [200] {"statusCode":200,"body":"Hello World!","headers":{"x-powered-by":"Express","content-type":"text/html; charset=utf-8","content-length":"12","etag":"W/\"c-Lve95gjOVATpfV8EL5X4nxwjKHE\"","date":"Thu, 13 Dec 2018 09:34:22 GMT","connection":"keep-alive"},"isBase64Encoded":false}

Skiping cache invalidation

Skiping cache invalidation is the same behavior as a deployed function

npm start -- --skipCacheInvalidation

Deploy

In order to deploy the endpoint, simply run:

sls deploy

The expected result should be similar to:

$ sls deploy
Serverless: Compiling with Typescript...
Serverless: Using local tsconfig.json
Serverless: Typescript compiled.
Serverless: Packaging service...
Serverless: Excluding development dependencies...
Serverless: Creating Stack...
Serverless: Checking Stack create progress...
.....
Serverless: Stack create finished...
Serverless: Uploading CloudFormation file to S3...
Serverless: Uploading artifacts...
Serverless: Uploading service .zip file to S3 (32.6 MB)...
Serverless: Validating template...
Serverless: Updating Stack...
Serverless: Checking Stack update progress...
..............................
Serverless: Stack update finished...
Service Information
service: serverless-nest-example
stage: dev
region: us-east-1
stack: serverless-nest-example-dev
api keys:
  None
endpoints:
  ANY - https://XXXXXXX.execute-api.us-east-1.amazonaws.com/dev/{proxy?}
functions:
  main: serverless-nest-example-dev-main
layers:
  None

Usage

Send an HTTP request directly to the endpoint using a tool like curl

curl https://XXXXXXX.execute-api.us-east-1.amazonaws.com/dev/hello

Tail logs

sls logs --function main --tail

Scaling

By default, AWS Lambda limits the total concurrent executions across all functions within a given region to 100. The default limit is a safety limit that protects you from costs due to potential runaway or recursive functions during initial development and testing. To increase this limit above the default, follow the steps in To request a limit increase for concurrent executions.

Cold start

Cold start may cause latencies for your application See : https://serverless.com/blog/keep-your-lambdas-warm/

These behavior can be fixed with the plugin serverless-plugin-warmup

  1. Install the plugin
npm install serverless-plugin-warmup --save-dev
  1. Enable the plugin
plugins:
  - '@hewmen/serverless-plugin-typescript'
  - serverless-plugin-optimize
  - serverless-offline
  - serverless-plugin-warmup
custom:
  # Enable warmup on all functions (only for production and staging)
  warmup:      
      - production
      - staging

Benchmark

A basic benchmark script can be used locally, it performs 1000 "GET" requests on "http://localhost:3000/hello"

# /!\ The app must run locally
npm start # Or npm start -- --skipCacheInvalidation for better performances
# Run bench
node bench.js

The expected result should be similar to:

$ node bench.js
1000 "GET" requests to "http://localhost:3000/hello"
total: 8809.733ms
Average:  8.794ms