Docker static ip connection timeout from outside - docker

Question

I am trying to assign my APP with a static IP. I think I have assigned the IP, but I cannot reach the IP from outside either curl or the browser.
docker-compose.yaml
version: '3.8'
services:
client:
container_name: client
build: ./frontend
ports:
- 3000:3000
working_dir: /app
volumes:
- ./frontend:/app/
- /app/node_modules
networks:
app_net:
ipv4_address: 172.16.238.10
hostname: client
command: npm run dev
networks:
app_net:
driver: bridge
ipam:
driver: default
config:
- subnet: "172.16.238.0/24"
Terminal message when I run it:
client | > frontend#0.0.0 dev
client | > vite
client |
client |
client | VITE v3.2.2 ready in 710 ms
client |
client | ➜ Local: http://localhost:3000/
client | ➜ Network: http://172.16.238.10:3000/
I can reach http://localhost:3000/ on the browser just fine. But whenever I try to reach http://172.16.238.10:3000/, I get a timeout. Something this on the browser:
This site can’t be reached
172.16.238.10 took too long to respond.
ERR_CONNECTION_TIMED_OUT
I can curl to the IP I assigned inside the docker container, but I cannot do it from outside. Is it possible to expose the IP to the outside?

Answer 1

If you manage to assign another IP address (172.16.238.10) to the host, the container can continue having a dynamic IP address. You can map the port 3000 only to the IP address 172.16.238.10.
Then you can connect to 172.16.238.10:3000 as so:
version: '3.8'
services:
client:
container_name: client
build: ./frontend
ports:
- 172.16.238.10:3000:3000
working_dir: /app
volumes:
- ./frontend:/app/
- /app/node_modules
networks:
- app_net
hostname: client
command: npm run dev
networks:
app_net:
driver: bridge

Answer 2

You probably want to look at using a macvlan network instead of bridged.

Answer 3

As a general rule, you can't access the container-private IP addresses at all. It happens to be possible on native Linux, not using Docker Desktop or another VM-based setup, and only if you're on the same machine as the container, but given all of these constraints it's usually better to not try it.
The standard way to access a container from outside is to declare ports: for it, and to use the host's DNS name or IP address and the published port number. Don't declare any IP-related setup in your Compose file at all.
Assuming your Dockerfile is correctly constructed, you should be able to reduce that Compose file to just
version: '3.8'
services:
client:
build: ./frontend
ports:
- 3000:3000
and calling http://host.example.com:3000/ using your host's DNS name, or http://localhost:3000 if you're on the same host, will forward to port 3000 in the container. None of the other Compose options are necessary.