Missing port conflict warnings on MacOS

[r13i]

Bug Report

Current Behavior

While trying to run on a custom port with --httpPort 5000, the listener starts normally but it seems the port is already used elsewhere without causing a conflict (see screenshot below).

Sample Code

This shouldn't be relevant in this situation, but here it is in case.

• file: serverless.yml (generated with sls print)

org: foo
app: foo-v2
service: foo
frameworkVersion: '3'
plugins:
  - serverless-esbuild
  - serverless-offline
provider:
  name: aws
  region: eu-west-1
  stage: dev
  runtime: nodejs14.x
  memorySize: 512
  timeout: 10
  apiGateway:
    description: The foo API
    minimumCompressionSize: 1024
    shouldStartNameWithService: true
    usagePlan:
      throttle:
        rateLimit: 10000
        burstLimit: 1000
  environment:
    STAGE: dev
    AWS_NODEJS_CONNECTION_REUSE_ENABLED: '1'
    NODE_OPTIONS: '--enable-source-maps --stack-trace-limit=1000'
  logRetentionInDays: 7
  logs:
    restApi: true
  deploymentBucket: null
  versionFunctions: true
  deploymentBucketObject:
    blockPublicAccess: true
    maxPreviousDeploymentArtifacts: 3
package:
  individually: true
functions:
  hello:
    handler: src/functions/hello/handler.main
    events:
      - http:
          method: get
          path: hello
    name: foo-dev-hello
resources:
  Resources: {}
  Outputs: {}
custom:
  esbuild:
    bundle: true
    minify: false
    sourcemap: true
    exclude:
      - aws-sdk
    target: node14
    define: {}
    platform: node
    concurrency: 10

• file: handler.ts

import type { APIGatewayHandler } from '@libs/apiGateway';
import { wrap } from '@libs/apiGateway';

const hello: APIGatewayHandler = async () => ({
  statusCode: 200,
  body: 'Hello, world!',
});

export const main = wrap(hello);

Expected behavior/code

It should just return a 200 Hello, world!

Environment

• serverless version:

sls --version
Framework Core: 3.12.0 (local) 3.12.0 (global)
Plugin: 6.2.1
SDK: 4.3.2

• serverless-esbuild version: "1.23.3",
• serverless-offline version: "8.5.0",
• node.js version: "v16.13.0"
• OS: macOS 12.2.1

Additional context/Screenshots

Start command:

See the response Server header:

[dherault]

Good catch, thanks!

[dnalborczyk]

thank you for filing this issue @redouane-dev

I don't believe this can be fixed on our end. node.js itself is throwing an error if the port is already in use, unless we are catching it and ignoring it, but I don't think that's what we are doing, just checked the code.

I also tried to start serverless-offline twice with the same port, and an error is being thrown.

✖ Unexpected error while starting serverless-offline server on port 6000: { Error: listen EADDRINUSE: address already in use ::1:6000

unfortunately I have no idea what would cause such an issue, but I believe it has something to do with your OS and the settings.

[dnalborczyk]

closing this for house keeping purposes.