cant reach docker container from outside host with port mapping - docker

Question

I am using a really simple docker-compose file from here:
https://github.com/brandonserna/flask-docker-compose
this is the docker compose file:
version: '3.5'
services:
flask-app-service:
build: ./app
volumes:
- ./app:/usr/src/app
- .:/user/src
ports:
- 5555:9999
However I can only reach the app from outside network when I am using port 80.
ports:
- 80:9999
When I am using for example port 8000. I cant reach the container from outside network.
From the local machine I can reach the app. (Tested with wget localhost:8000)
ports:
- 8000:9999
iptables -L gives me this:
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
DOCKER-USER all -- anywhere anywhere
DOCKER-ISOLATION-STAGE-1 all -- anywhere anywhere
ACCEPT all -- anywhere anywhere ctstate RELATED,ESTABLISHED
DOCKER all -- anywhere anywhere
ACCEPT all -- anywhere anywhere
ACCEPT all -- anywhere anywhere
ACCEPT all -- anywhere anywhere ctstate RELATED,ESTABLISHED
DOCKER all -- anywhere anywhere
ACCEPT all -- anywhere anywhere
ACCEPT all -- anywhere anywhere
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
Chain DOCKER (2 references)
target prot opt source destination
ACCEPT tcp -- anywhere 172.18.0.2 tcp dpt:9999
ACCEPT tcp -- anywhere 172.17.0.2 tcp dpt:http
Chain DOCKER-ISOLATION-STAGE-1 (1 references)
target prot opt source destination
DOCKER-ISOLATION-STAGE-2 all -- anywhere anywhere
DOCKER-ISOLATION-STAGE-2 all -- anywhere anywhere
RETURN all -- anywhere anywhere
Chain DOCKER-ISOLATION-STAGE-2 (2 references)
target prot opt source destination
DROP all -- anywhere anywhere
DROP all -- anywhere anywhere
RETURN all -- anywhere anywhere
Chain DOCKER-USER (1 references)
target prot opt source destination
RETURN all -- anywhere anywhere

Answer 1

Not enough for comment so this is why:
From what it seems it could be either firewall rule in your host running the container or one between the host to your house.
To test which on between the two I'd try to use nmap with --reason and --tracerout options, since we have connectivity in another port it's unlikely that there is a complete block between your home and the container so the traceroute wouldn't give much info but just in case.
Also if you have root access to the host machine or just to the iptables service try to stop it to check if that's the root cause for the block.
also check with docker ps if the port is bound to the port on the machine, should look something like this:
0.0.0.0:port --> tcp\port
where instead of port you have the port number
If it doesn't maybe it's due to some problem with the docker-compose up command so try to run the service with a simple docker run command