Maximum number of docker networks

possiblylinux127 , 2 months ago

It sounds like your outgrowing docker. Maybe switch to Kubernetes at some point?

rambos OP , 2 months ago

Oh rly? Im still reading about what others said and feels like I can still continue with docker. Ive heard about kubernetes many times. Even tho some people use them on single node, isnt that made for multiple nodes setup? I have to learn more about kubernetes

kylian0087 , 2 months ago

Take a look at K3S if you plan to use kubernetes on a single node.

rambos OP , 2 months ago

Will check, thank you

TCB13 , 2 months ago

Only if there was IPv6: https://docs.docker.com/config/daemon/ipv6/

Just run all your containers with IPv6 randomly generated prefixes and this won't ever be a problem, you'll also get more IP spacing than you'll ever require. Then use your reverse proxy to convert between the "public" IPv4 space and the internal docker IPv6 networks.

Another option is to reduce the size of your IPv4 pools like this guy described.

TheButtonJustSpins , 2 months ago (edited 2 months ago)

Docker network pools are huge by default. I had to change this as well.

This article covers the issue and the solution in detail:
https://straz.to/2021-09-08-docker-address-pools/

If you just want the solution, skip to the section titled How to configure docker to allow >500 bridge networks. I think you'll need to remake all your networks after making the change, if I remember correctly.

Here's my config now:

$ sudo cat /etc/docker/daemon.json
{
  "default-address-pools": [
    { "base":"172.16.0.0/12", "size":24 },
    { "base":"172.17.0.0/12", "size":24 },
    { "base":"172.18.0.0/12", "size":24 },
    { "base":"172.19.0.0/12", "size":24 },
    { "base":"172.20.0.0/12", "size":24 },
    { "base":"172.21.0.0/12", "size":24 },
    { "base":"172.22.0.0/12", "size":24 },
    { "base":"172.23.0.0/12", "size":24 },
    { "base":"172.24.0.0/12", "size":24 },
    { "base":"172.25.0.0/12", "size":24 },
    { "base":"172.26.0.0/12", "size":24 },
    { "base":"172.27.0.0/12", "size":24 },
    { "base":"172.28.0.0/12", "size":24 },
    { "base":"172.29.0.0/12", "size":24 },
    { "base":"172.30.0.0/12", "size":24 },
    { "base":"172.31.0.0/12", "size":24 }
  ],
  "log-opts": {
    "max-size": "1g"
  }
}

rambos OP , 2 months ago

Thx, Ill read that, it looks promising

Markaos , 2 months ago

I'm pretty sure all of those entries are in the same /12 network - 172.16.0.0/12. Apparently there's nothing wrong with it, but I think you can significantly simplify that config by just removing all the extra ones

TheButtonJustSpins , 2 months ago

Good point!

timbuck2themoon , 2 months ago (edited 2 months ago)

Could simplify it by making a 28 block at most. That is 14 IPs per bridge which seems like way more than one would generally need anyhow.

{
  "default-address-pools": [
    { "base":"172.16.0.0/12", "size":28 },
  ]
}

5PACEBAR , 2 months ago

Had to do exactly that last week when I hit Docker's rather low network limit.

originalucifer , 2 months ago

sounds like your issue isnt with the number of networks, but how youre addressing them. fix that.

if youve got a container that only needs a single or a few ip's then its defined network should reflect that.

rambos OP , 2 months ago

Thank you! This will be more clear after more research I hope. My understanding of docker networks is still meh...gonna change it now

eager_eagle , 2 months ago

then you'd limit the existing network addresses using subnets, as suggested by another answer in that question