How can I grab exposed port from inspecting docker container? - sed

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

Answer 4

Using jq:
docker inspect --format="{{json .}}" my-container | jq '.NetworkSettings.Ports["1234/tcp"][0].HostPort'
Change 1234 with the port you specified in docker run.

Answer 5

I have used both docker inspect <container> and docker inspect <container>| jq combination to strip ports.
In below example I am looking at dsb-server container and port I am looking for is 8080/tcp
docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
98b4bec33ba9 xxxxx:dsbv3 "./docker-entrypoint." 6 days ago Up 6 days 8009/tcp, 0.0.0.0:4848->4848/tcp, 8181/tcp, 0.0.0.0:9013->8080/tcp dsb-server
to strip ports
docker inspect dsb-server| jq -r '.[].NetworkSettings.Ports."8080/tcp"[].HostPort'
9013
docker inspect --format='{{(index (index .NetworkSettings.Ports "8080/tcp") 0).HostPort}}'
9013

Answer 6

The above answers were close and put me on the right track, but I kept getting the following error:
Template parsing error: template: :1: unexpected "/" in operand
I found the answer here: https://github.com/moby/moby/issues/27592
This is what finally worked for me:
docker inspect --format="{{(index (index .NetworkSettings.Ports \"80/tcp\") 0).HostPort}}" $INSTANCE_ID