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Maximum number of docker networks (lemm.ee)

submitted 7 months ago by [email protected] to c/[email protected]

14 comments fedilink hide all child comments

Hey guys, I was happily running 44 docker containers for a while on Debian host. Today I tried to add a new service (uptime-kuma) using portainer stacks, but I got this error:

Error response from daemon: could not find an available, non-overlapping IPv4 address pool among the defaults to assign to the network

Quick google led me to this link where I found possible problem with max number of docker networks. I did docker network prune, it removed 5 networks that were not in use and viola, uptime-kuma is working now!

Am I reaching the limit? What to do if I need 10 more services on the same host? I bet I saw some people in this community running many more services

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[–] [email protected] 18 points 7 months ago* (last edited 7 months ago) (5 children)

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"
  }
}

[–] [email protected] 4 points 7 months ago (3 children)

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

[–] [email protected] 6 points 7 months ago* (last edited 7 months ago) (1 children)

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 },
  ]
}

[–] [email protected] 3 points 7 months ago

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

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