Unable to connect to local server

[mbrg]

Bug Report

serverless offline start executes successfully, but I'm unable to connect to the local server. I'm trying to POST to the Lambda endpoint with curl but I get no response (and no logs on the server process either).

To verify that this is not a firewall issue, I used node's http-server and was successfully able to call it with curl 127.0.0.1:8080.

Current Behavior

Running serverless offline executes successfully:

$ SLS_DEBUG=* sls offline start --migrate --verbose --stage local

Serverless: Running "serverless" installed locally (in service node_modules)
...
...
offline: Offline [http for lambda] listening on http://localhost:4002
offline: Function names exposed for local invocation by aws-sdk:
           * collector: collectors-service-local-collector
[offline] Lambda Invocation Routes (for AWS SDK or AWS CLI):
           * POST http://localhost:4002/2015-03-31/functions/myfunction/invocations
[offline] Lambda Async Invocation Routes (for AWS SDK or AWS CLI):
           * POST http://localhost:4002/2014-11-13/functions/myfunction/invoke-async/

Curl waits forever:

$ curl -X POST 127.0.0.1:4002/2015-03-31/functions/myfunction/invocations
# never returns

$ curl -X POST localhost:4002/2015-03-31/functions/myfunction/invocations
# never returns

$ curl -X POST http://127.0.0.1:4002/2015-03-31/functions/myfunction/invocations
# never returns

$ curl -X POST http://localhost:4002/2015-03-31/functions/myfunction/invocations
# never returns

Connection thru Python3 boto3 doesn't work as well

import boto3
cli = boto3.client("lambda", endpoint_url=f"http://localhost:4002/")
cli.invoke(FunctionName="myfunction",InvocationType="RequestResponse")

botocore.exceptions.ReadTimeoutError: Read timeout on endpoint URL: "http://localhost:4002/2015-03-31/functions/myfunction/invocations"

Sample Code

• file: serverless.yml

service: <my-service>

frameworkVersion: '2'

plugins:
  - serverless-python-requirements
  - serverless-iam-roles-per-function
  - serverless-pseudo-parameters
  - serverless-plugin-scripts
  - serverless-offline

package:
  exclude:
    - .dynamodb/**
    - .pytest_cache/**
    - node_modules/**
  excludeDevDependencies: false

provider:
  name: aws
  runtime: python3.6
  stage: ${opt:stage}
  region: ${opt:region}
  tracing:
    apiGateway: true
    lambda: true
  logRetentionInDays: 7

custom:
  serverless-offline:
    httpPort: 4000
    lambdaPort: 4002
    stage: local
  pythonRequirements:
    pythonBin: python3.6
    slim: true
    slimPatternsAppendDefaults: false
    slimPatterns:
      - "**/*.pyc"
      - "**/*.pyo"
      - "**/__pycache__*"
    invalidateCaches: true
    useStaticCache: false
    vendor: ../common/src

functions:
  myfunction:
     handler: src/handler.handler
     iamRoleStatementsInherit: true
     maximumEventAge: 21600 # 6 hours in seconds
     maximumRetryAttempts: 2
     events:
       - eventBridge:
           eventBus: <my-eventbus-arn>
           pattern:
             source:
             - <my-source>
             detail-type:
              - <my-detail>

Expected behavior/code
Being able to invoke functions locally.

Environment

• serverless version: 2.17.0
• serverless-offline version: 6.8.0
• node.js version: v15.5.1
• OS: Ubuntu-18.04.05 LTS (running on Win10 19042.685 using WSL2)
• python version: 3.6.9

[hajekjiri]

As pointed out in #1150, this seems to be an issue with node v15.5.x. Downgrading to v15.4.0 should fix the problem.

I downgraded to the LTS (v14.15.4) because that was the easiest solution with my package manager and it also fixed the issue.

[mbrg]

Thanks @hajekjiri, that worked!