How can I grab exposed port from inspecting docker container?

Question

Assuming that I start a docker container with the following command

docker run -d --name my-container -p 1234 my-image

and running docker ps shows the port binding for that image is...

80/tcp, 443 /tcp. 0.0.0.0:32768->1234/tcp

Is there a way that I can use docker inspect to grab the port that is assigned to be mapped to 1234 (in this case, 32768)?

Similar to parsing and grabbing the IP address using the following command...

IP=$(docker inspect -f "{{ .Networksettings.IPAddress }} my-container)

I want to be able to do something similar to the following

ASSIGNED_PORT=$(docker inspect -f "{{...}} my-container)

I am not sure if there is a way to do this through Docker, but I would imagine there is some command line magic (grep,sed,etc) that would allow me to do something like this.

When I run docker inspect my-container and look at the NetworkSettings...I see the following

"NetworkSettings": {
        ...
        ...
        ...
        "Ports": {
            "1234/tcp": [
                {
                    "HostIp": "0.0.0.0",
                    "HostPort": "32768"
                }
            ],
            "443/tcp": null,
            "80/tcp": null
        },
        ...
        ...
    },

In this case, I would want it to find HostPort without me telling it anything about port 1234 (it should ignore 443 and 80 below it) and return 32768.

Answer 1

Execute the command: docker inspect --format="{{json .Config.ExposedPorts }}" src_python_1

Result: {"8000/tcp":{}}

Proof (using docker ps):

e5e917b59e15        src_python:latest   "start-server"         22 hours ago        Up 22 hours         0.0.0.0:8000->8000/tcp                                        src_python_1

Answer 2

It is not easy as with ip address as one container can have multiple ports, some exposed and some not, but this will get it:

sudo docker inspect name | grep HostPort | sort | uniq | grep -o [0-9]*

If more than one port is exposed it will be displayed on a new line.

Answer 3

There are two good options depending on your taste: docker port my-container 1234 | grep -o [0-9]*$ and docker inspect --format='{{(index (index .NetworkSettings.Ports "1234/tcp") 0).HostPort}}' my-container