I can make my Docker Python HTTPD listen to the external ip but not from outside docker. Why?

Rahul Gopinath

11/11/23, 2:41 AM

I am not sure if this is relevant, but I am on one of the Oracle Compute instances, and I am using an Ubuntu 22.04 instance. I have opened the right ports so that the server is accessible to the outside world.

Now, here is what is strange: I try the following command.

sudo python3 -m http.server --bind 0.0.0.0 80

And I try to access it from an outside machine with

wget <myip>:80

--2022-11-10 17:39:27--  http://<myip>/
Connecting to   <myip>:80... failed: Connection refused.

Next, I try this:

docker run -p 80:80 -it --entrypoint /bin/sh python:slim
# python3 -m http.server --bind 0.0.0.0 80

Now, surprisingly, wget works.

wget <myip>:80

Connecting to <myip>:80... connected.
HTTP request sent, awaiting response... 200 OK

So, my question is, why am I seeing this? How do I make the Python HTTP server outside the docker listen to the outside world?

Connecting to 168.138.101.164:80... connected. HTTP request sent, awaiting response... 200 OK

For reference, here is my Ingress configuration in the oracle cloud.

I was sent here from stackoverflow.

226

1 + 3

networking

python

docker

jabbson

11/11/23, 3:28 AM

when you start the `http.server` with the first command, open another terminal with the same server and run `sudo netstat -tulnp | grep ":80"`. Tell us what you see.

Rahul Gopinath

11/11/23, 5:01 AM

This was caused due to `iptables` misconfiguration. Once I flushed the iptables with `iptables -F`, I am able to connect. Should I close this question?

Gerald Schneider

11/11/23, 7:38 AM

Either that, because it's trivial and is basically being asked every day. Or you post an answer and accept it.

Score:0

Server

Rahul Gopinath

11/11/23, 8:30 PM

Answer my question as @Gerald Schneider suggests, because this is a new installation of an Oracle cloud compute instance, so it is possible that others will also hit the same error I hit.

My problem was that the iptables were misconfigured out of the box. I realized the issue after reviewing this answer which pointed out that docker was effectively a new machine with respect to networking. So, after flusing the iptables with iptables -F from the main box, the problem went away.

+ 0

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: I can make my Docker Python HTTPD listen to the external ip but not from outside docker. Why?

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