How to fix `Error listen EADDRINUSE: address already in use` in azure app service?

Question

I have a nodejs/express app which I'm deploying to Azure Appservice on Linux platform. Azure provides the port 8080 on which my app runs. However, when I deploy it, it gives me an error

Error listen EADDRINUSE: address already in use :::8181
error Command failed with exit code 1.

the main command with which I'm running the app is env NODE_ENV=production node index.js.

The port that the app uses is 8080. But the error that's coming is for port 8181. I've tried restarting the server and redeploying it many times over.

I followed this tutorial to deploy. https://learn.microsoft.com/en-us/azure/app-service/quickstart-nodejs?pivots=platform-linux

I've deleted the whole appservice and its plan and redeployed it only to find the same error.

I ssh into the container and checked if 8181 is in use. But it isn't.

Here is how I am starting the application:

const port = 8080;
const server = app.listen(process.env.PORT || port, () => {
    console.log(`App running on port ${port}`);
});

Here's a screenshot of the deploy log

What should I do?

EDIT:

Here's my package.json

{
    "name": "test-express",
    "version": "1.0.0",
    "main": "index.js",
    "license": "MIT",
    "scripts": {
        "test": "echo \"Error: no test specified\" && exit 1",
        "dev": "nodemon index.js",
        "build:azure": "env NODE_ENV=production node index.js"
    },
    "dependencies": {
        "express": "^4.17.1",
        "morgan": "^1.10.0"
    },
    "devDependencies": {
        "nodemon": "^2.0.7"
    }
}

In the official documentation that I've mentioned below, one of the scripts that starts the application is "build:azure".

Moreover, I added these lines to my code to see what environment variables are getting passed.

console.log("=============");
console.log(process.env.PORT, process.env.NODE_ENV);
console.log("=============");

and the final result of the build process that I got was

...
7:00:08 pm test-express: [1/4] Resolving packages...
7:00:09 pm test-express: [2/4] Fetching packages...
7:00:30 pm test-express: info fsevents@2.3.2: The platform "linux" is incompatible with this module.
7:00:30 pm test-express: info "fsevents@2.3.2" is an optional dependency and failed compatibility check. Excluding it from installation.
7:00:30 pm test-express: [3/4] Linking dependencies...
7:00:45 pm test-express: [4/4] Building fresh packages...
7:00:45 pm test-express: Done in 37.21s.
7:00:45 pm test-express: Running 'yarn run build:azure'...
7:00:46 pm test-express: yarn run v1.22.10
7:00:46 pm test-express: $ env NODE_ENV=production node index.js
7:00:46 pm test-express: =============
7:00:46 pm test-express: 8181 production
7:00:46 pm test-express: =============
7:00:46 pm test-express: events.js:292
7:00:46 pm test-express:       throw er; // Unhandled 'error' event
7:00:46 pm test-express:       ^
7:00:46 pm test-express: info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
7:00:46 pm test-express: Error: listen EADDRINUSE: address already in use :::8181
7:00:46 pm test-express:     at Server.setupListenHandle [as _listen2] (net.js:1318:16)
7:00:46 pm test-express:     at listenInCluster (net.js:1366:12)
7:00:46 pm test-express:     at Server.listen (net.js:1452:7)
7:00:46 pm test-express:     at Function.listen (/tmp/8d8e87f8a5dd6db/node_modules/express/lib/application.js:618:24)
7:00:46 pm test-express:     at Object.<anonymous> (/tmp/8d8e87f8a5dd6db/index.js:8:20)
7:00:46 pm test-express:     at Module._compile (internal/modules/cjs/loader.js:1063:30)
7:00:46 pm test-express:     at Object.Module._extensions..js (internal/modules/cjs/loader.js:1092:10)
7:00:46 pm test-express:     at Module.load (internal/modules/cjs/loader.js:928:32)
7:00:46 pm test-express:     at Function.Module._load (internal/modules/cjs/loader.js:769:14)
7:00:46 pm test-express:     at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:72:12)
7:00:46 pm test-express: Emitted 'error' event on Server instance at:
7:00:46 pm test-express:     at emitErrorNT (net.js:1345:8)
7:00:46 pm test-express:     at processTicksAndRejections (internal/process/task_queues.js:80:21) {
7:00:46 pm test-express:   code: 'EADDRINUSE',
7:00:46 pm test-express:   errno: -98,
7:00:46 pm test-express:   syscall: 'listen',
7:00:47 pm test-express:   address: '::',
7:00:47 pm test-express:   port: 8181
7:00:47 pm test-express: }
7:00:47 pm test-express: error Command failed with exit code 1.
7:00:49 pm test-express: /opt/Kudu/Scripts/starter.sh oryx build /tmp/zipdeploy/extracted -o /home/site/wwwroot --platform nodejs --platform-version 14 -i /tmp/8d8e87f8a5dd6db -p compress_node_modules=tar-gz --log-file /tmp/build-debug.log 
7:01:07 pm test-express: Deployment failed.

So yes, 8181 is getting passed.

FIXED:

Yes, I got it fixed by changing the script attribute build:azure to start. That was the only change I needed to make in package.json to get it to run.

can you post the screeshot? appservice does not expose port 8081 — Sajeetharan, Mar 14 '21 at 10:55
In the whole project, global search `8181` to see if there is relevant code, remember to use `process.env.PORT || 8080` instead. — Jason Pan, Mar 14 '21 at 13:13
@JasonPan I did a global search for `8181` and nothing came up. Yes I'm already using `process.env.PORT || 8080` — Kartikeya Gokhale, Mar 14 '21 at 14:36
@JasonPan I logged the port that app service is passing and its actually passing 8181 as process.env.PORT. I manually deployed it to 8080 but its not getting deployed. It just errors out. Cant even see the logs through the portal. — Kartikeya Gokhale, Mar 14 '21 at 19:55
@KartikeyaGokhale Pls follow my step show us Application Logs (all of them ), so we can help you. — Jason Pan, Mar 15 '21 at 01:39
@KartikeyaGokhale Pls also run `netstat -tunlp`, [and show us result img](https://i.imgur.com/zfOvfEe.png). — Jason Pan, Mar 15 '21 at 01:42
@JasonPan yes i fixed the issue. Was starting my app using "build:azure" as mentioned in the documentation. Had to change it to "start" and that did the trick. Thanks for your help!! — Kartikeya Gokhale, Mar 27 '21 at 15:58

Jason Pan · Answer 1 · 2021-03-15T01:38:14.017

UPDATE

TroubleShoot :

Step 1 :

Step 2 :

Step 3 :

PRIVIOUS

Please modify the code in the code about listening.

Exp: const port = process.env.PORT || 8080

const express = require('express')
const app = express()
const port = process.env.PORT || 8080

app.get('/', (req, res) => {
  res.send('Hello World!')
})

app.listen(port, () => {
  console.log(`Example app listening at http://localhost:${port}`)
})

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If you change the port setting to process.env.PORT If it doesn't work.

Step 1: it is recommended to use git for continuous deployment, and the port setting is the same process.env.PORT According to the method in the post for reference. Then check whether the website is working properly.

Step 2: if the website fails to start normally, it is recommended to add start command. The first command to try is npx serve -s.

Step 3: if the command in step 2 does not work, use pm2 serve /home/site/wwwroot --no-daemon --spa.

How to fix `Error listen EADDRINUSE: address already in use` in azure app service?

1 Answers1

If you change the port setting to process.env.PORT If it doesn't work.

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