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How to use port mapping / forwarding

General Discussions
#1

hello everyone

just a short question and I imagine it is quite simple but I cannot get it right:
let’s say I deploy a container that runs normally on port 8000. Since port 8000 is already used by another app I wanna map that port to 8001 (as when starting a container just by using docker cli)

so creating a new contrainer (I use portainer for this) and map ports --> host: 8001 --> container: 8000

that’s how I tried it and it still creates the container only accessible over webgui on port 8000 …

maybe some information that is needed to solve this: i start my containers in the network “host” so that they are accessible over the IP of the host (i.e. something like 192.168.1.XXX instead of docker’s IP 172.17.0.1) …

does anyone know what im understanding wrong here?

thanks for your help

#2

There is no such thing as publishing ports if the container is running with --network host, all ports occupied by processes in the container will be directly bound to a host port.

If you want to publish ports, you will need to use a bridged or overlay network.

#3

thank you for the answer meyay! i was thinking that the problem might be there…

so that’s the thing then: I use network “host” so that I can access the container over the IP address of the VM. might you be able to explain to me how I can achieve that without using --network host?

thanks so much and best regards

#4

I will leave this one to others.

Though, If you actualy want to learn docker, I can highly recommend this excellent free self-paced training: https://container.training/intro-selfpaced.yml.html. Docker makes more fun, if you actualy know how it works and needs to be used, instead of having to rely on forums to solve your problem of the hour…

#5

hey again

thanks, I will do that and answer my question as soon as I find the solutions so others might find it in the future!

best regards

#6

Log in to the router as admin. …
Locate the port forwarding options. …
Type the port number or port range that you want to forward. …
Choose a protocol, either TCP or UDP. …
Type the static IP address you chose. …
Enable the port forwarding rule with an Enable or On option.