How to access web page served by nginx web server running in docker container

Question

We are trying to use docker to run nginx but for some reason I'm unable to access the nginx web server running inside the docker container.

We have booted a Docker Container using the following Dockerfile: https://github.com/dwyl/learn-docker/blob/53cca71042482ca70e03033c66d969b475c61ac2/Dockerfile

(Its a basic hello world using nginx running on port 8888) To run the container we used:

docker run -it ubuntu bash

we determined the Container's IP address using the docker inspect command:

docker inspect --format '{{ .NetworkSettings.IPAddress }}' a9404c168b21

which is: 172.17.0.11

when I try to visit the container's IP address and the nginx port in a browser http://172.17.0.11:8888/ we get ERR_CONNECTION_TIMED_OUT

or using curl:

curl 172.17.0.11:8888
curl: (7) Failed to connect to 172.17.0.11 port 8888: Connection refused

To attempt to solve this we googled extensively but suspect we might be asking the "wrong" questions...

Answer 1

You shouldn't be trying to hit the IP address of the container, you should be using the IP address of the host machine.

What you are missing is the mapping of the port of the host machine to the port of the container running the nginx server.

Assuming that you want to use port 8888 on the host machine, you need a parameter such as this to map the ports:

docker run ... -p 8888:8888 ...

Then you should be able to access you server at http://<HOST_MACHINE_IP>:8888

EDIT: There is another gotcha if you are running on a Mac. To use Docker on a Mac it's common to use boot2docker but boot2docker adds in another layer. You need determine the IP address of the boot2docker container and use that instead of localhost to access nginx.

$ boot2docker ip

The VM's Host only interface IP address is: <X.X.X.X>

$ wget http://<X.X.X.X>:8888
...
Connecting to <X.X.X.X>:8888... connected.
HTTP request sent, awaiting response... 200 OK

Reference: https://viget.com/extend/how-to-use-docker-on-os-x-the-missing-guide

EDIT: ... or with docker-machine the equivalent command would be docker-machine ip <machine-name> where <machine-name> is likely to be "default".