Docker container does not respond to http request - node.js

Question

I'm trying to send an http request through axios, from my localhost (node server) to a docker container (which contains a simple server in node too) which belongs to a docker network, and identified by an specific IP.
I have used postman, xmlhttprequests, and axios but nothing seems to work. I have also tried with get and post requests but any of those get any answer from the container side.
Do you have any Idea of what am I doing wrong?
the .sh file that Im running to launch the container is:
docker build -t connectimg .
docker network create --subnet=119.18.0.0/16 mynet
docker run -d --name instance2 -p 4002:4000 --net mynet --ip 119.18.0.2 connectimg
and the docker logs result for the instance post-launch is:
{
lo: [
{
address: '127.0.0.1',
netmask: '255.0.0.0',
family: 'IPv4',
mac: '00:00:00:00:00:00',
internal: true,
cidr: '127.0.0.1/8'
}
],
eth0: [
{
address: '119.18.0.2',
netmask: '255.255.0.0',
family: 'IPv4',
mac: '02:42:77:12:00:02',
internal: false,
cidr: '119.18.0.2/16'
}
]
}
Example app listening on port 3000
My Docker Instance Node app code is:
const express = require('express')
const app = express()
const port = 3000
const cors = require('cors')
var os = require('os');
app.use(cors());
app.use(express.json());
app.listen(port, () => {
console.log(`Example app listening on port ${port}`)
})
app.get('/listen', (req,res) => {
console.log('got it');
})
var networkInterfaces = os.networkInterfaces();
console.log(networkInterfaces);
And my Node server piece of code responsible of sending the get request to the instance is:
const connect = (req,res) => {
axios.get('http://119.18.0.2:3000/listen').then(resp => {
console.log(resp.data);
});
}
and the error I keep getting is:
ETIMEDOUT 119.18.0.2:3000
at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1159:16)

Answer 1

Firstly, your URI http://119.18.0.2:3000/listen is incorrect. The docker network cannot be accessed directly as it is not a network that the host knows of.
The option -p 4002:4000 is what is exposing your docker container to the host(and the network you're connected to). 4002 is the port exposed to the host and port 4000 is the port your container is exposing INSIDE the docker network
To access the container from the host your URI would become http://localhost:4002/listen
To access the container from a different machine on the same network the URI would become http://<ip-address-of-this-machine>:4002/listen. You can find your IP using ipconfig in command prompt on Windows, or ifconfig in terminal on Linux based systems.
Secondly, your port allocations are mismatched. You set the port in your node app using const port = 3000 and exposed port 4000 of the container using -p 4002:4000 in your docker run command.
Either change your node application to expose port 4000 using const port = 4000
OR
Change your docker run command to expose port 3000 of the container by using -p 4002:3000.
Docker networks can be a bit confusing at first. Read up on them or check the documentation(hella useful), it will serve you well in future development. :)
EDIT: You can properly containerize your node application using a DockerFile similar to this:
FROM node:lts-alpine3.15
LABEL maintainer="MyDevName"
WORKDIR /usr/app
COPY ./myNodeApp ./
RUN npm install
CMD ["npm", "start"]
So that your node app runs automatically on start.

Answer 2

the .sh file that Im running to launch the container is:
docker build -t connectimg .
docker network create --subnet=119.18.0.0/16 mynet
docker run -d --name instance2 -p 4002:4000 --net mynet --ip 119.18.0.2 connectimg
if will leverage docker-compose, you might not need the script.
I'm trying to send an http request through axios, from my localhost (node server) to a docker container (which contains a simple server in node too) which belongs to a docker network, and identified by an specific IP.
seems like 2 things need to be tweaked:
use 0.0.0.0:4200 in the dockerized server.
verify the network that you associate with the container is reachable from your host operating system. if the docker network is not that important, you can just ditch it