Multiple instances on one server?

[cpbreton]

Is it possible to run multiple instances of Valheim on one host/behind one public IP address? Or will Steam/Valheim only recognize the instance on the 2456-8 ports?

[InB4DevOps]

I read on reddit that some users have multiple servers running on the same IP.
As long as you have enough cores & RAM I don't see an issue.

[cpbreton]

so just use different ports for each and Steam/Valheim clients will see them?

[InB4DevOps]

well, there's still the problem, that Steam / Valheim can only show ~5000 servers so you might need to connect via IP:port (new in latest version) or favourites list but other than that there shouldn't be a problem.

[Addyvan]

@cpbreton You should be fine as long as the ports don't overlap. Let me know how it goes.

[lloesche]

@seventh88 see #174

You would start a second container and map different ports.

E.g.

$ docker run -d \
    --name valheim-server1 \
    --cap-add=sys_nice \
    -p 2456-2457:2456-2457/udp \
    -v $HOME/valheim-server1/config:/config \
    -v $HOME/valheim-server1/data:/opt/valheim \
    lloesche/valheim-server

$ docker run -d \
    --name valheim-server2 \
    --cap-add=sys_nice \
    -p 2466-2467:2456-2457/udp \
    -v $HOME/valheim-server2/config:/config \
    -v $HOME/valheim-server2/data:/opt/valheim \
    lloesche/valheim-server

plus whatever else options you're using. Make sure to have at least 4 cores and around 16 GB RAM. Or 8 GB RAM and something like 20 GB swap.

Then you can connect to valheim-server1 on port 2456 and to valheim-server2 on port 2466.

[seventh88]

Worked! Thank you!

[Mood93]

@lloesche Would we have to edit the below files as well? Or does the SERVER_PORT variable overwrite those?

https://github.com/lloesche/valheim-server-docker/search?q=2456
Dockerfile ln 144
valheim.service ln 19
valheim-status ln 163

The reason I ask is because when I use a different port, 'docker ps' shows 2456 is used to some degree.

Any recommendations? Thanks!

[lloesche]

@Mood93 there's no need to change any of those or even the SERVER_PORT variable to run any number of instances on the same system. All you need to do is tell Docker at startup to map the container ports to some other host ports.

Example:

-p 2456-2457:2456-2457/udp

means "Map container ports 2456 and 2457 to host ports 2456 and 2457 respectively".

But then

-p 2466-2467:2456-2457/udp

means "Map container ports 2456 and 2457 to host ports 2466 and 2467 respectively".

So you see, the ports inside the container can stay the same. Each container has its own networking and they don't conflict. Hence no need to change SERVER_PORT. It is only the ports those container ports get mapped to on the host that change.

For completeness:
The only reason I can think of why you would ever have to change SERVER_PORT is if you run Docker with host networking --net host. Which is not recommended. In this mode the container gets raw access to the hosts network interfaces and so if you would then run two containers with the same ports they would conflict.

[lloesche]

The reason I ask is because when I use a different port, 'docker ps' shows 2456 is used to some degree

Can you describe how you run this container? Just docker run? If so what is the exact command you are using. Or docker-compose up? If so what does your compose file look like? Are you using the one from this repo?