Why WEBSITES_PORT and PORT in Microsoft.Web/sites is ignored, as well as, EXPOSE in the dockerfile?

Question

Why WEBSITES_PORT and PORT in Microsoft.Web/sites is ignored, as well as, EXPOSE in the .dockerfile?

Our docker keeps crashing when the health check fails. There is no respond to the HTTP pings.

We get messages such as didn't respond to HTTP pings on port: 8080 as shown below:

Explanation

We are running a function app and a web app, done on Nodejs, on the same Azure App Service plan.

A single resource Microsoft.Web/serverfarms is created of kind Linux using Basic B2 plan.

Then, two Microsoft.Web/sites are created: One of kind functionapp,linux for the function app in and another of kind app for the Nodejs web app.

Our web app is a simple Nodejs using express server which is listening to the port:

const express = require('express')
const session = require('express-session')
...
const app = express()
...
const port = process.env.PORT || '3000'
app.set('port', port)
app.listen(port, () => console.log(`App started on port ${port}`))

Attempts

The following is a list of steps we have tried and had failed:

• We increased the plan from Basic B2 to Basic B3
• We used WEBSITES_PORT and/or PORT in the Microsoft.Web/sites for the web app. Also, we had created a .dockerfile with EXPOSE keyword inside the web app itself.
• We tried applying WEBSITES_WEBDEPLOY_USE_SCM set to false
• We changed the end of files from CR LF to LF in the git repository, applying the change and re-normalizing.
• We set linuxFxVersion and/or nodeVersion
• In Microsoft.Web/sites for the web app,
• We set http20Enabled from true to false and applied different versions of minTlsVersion
• We played with healthCheckPath, autoHealEnabled, autoHealRules and loadBalancing
• We tried increasing WEBSITES_CONTAINER_START_TIME_LIMIT
• We tried to include the folder node_modules to the repository
• We tried to create a home directory and even a startup.sh file
• We tried increasing WEBSITES_CONTAINER_START_TIME_LIMIT
• We tried adding app.set('trust proxy', 1)
• We tried adding a capture for all 404 errors
• We created two Microsoft.Web/serverfarms. One for the Function App and another for the Web App
• We tried adding DOCKER_ENABLE_CI as true
• We tried to add the flags used in the App Service (such as WEBSITES_PORT) using the appSettings property of task AzureWebApp@1 in our deployment YAML file

We even added an entry point:

app.get('/api/health/', function(req, res){
  res.status(200).send('OK')
})

Finally, we spend days searching online and trying everything we encountered and since we are still not solving this issue, we were wondering if someone could spot what are we missing.

In advance, thanks for going over this long explanation and appreciate any help you can provide me.

Answer 1

My coworker Albert Linga found out what as the root cause of the problem.

Under Microsoft.Web/sites, properties, siteConfig, there is the property remoteDebuggingEnabled. This property must be disabled (false). Plus, the kind attribute must be changed from app to app,linux.

Then, in the task AzureWebApp@1, we changed the property runtimeStack to NODE|12-lts so it matches the property linuxFxVersion (NODE|12-lts) which is inside siteConfig, under Microsoft.Web/sites