While playing with Docker I wanted to know how many containers I could spawn on a single system.
A quick for-loop told me that the maximum is 1023 containers on a single host:
Error response from daemon: Cannot start container 09c8f46b59ccc311e8d0352789db6debd0fa1df98186c5cda98583d762d48601: adding interface vetha5d205e to bridge docker0 failed: exchange full
The limitation here is the Linux bridging which can’t have more then 1023 interfaces attached. Specifically net/bridge/br_private.h BR_PORT_BITS cannot be extended because of spanning tree requirements.
wido@wido-desktop:~$ docker ps|wc -l 1024 wido@wido-desktop:~$
Although that says 1024 there is a header line, so we have to subtract one. That brings it to 1023.
wido@wido-desktop:~$ docker version Client: Version: 1.8.3 API version: 1.20 Go version: go1.4.2 Git commit: f4bf5c7 Built: Mon Oct 12 05:37:18 UTC 2015 OS/Arch: linux/amd64 Server: Version: 1.8.3 API version: 1.20 Go version: go1.4.2 Git commit: f4bf5c7 Built: Mon Oct 12 05:37:18 UTC 2015 OS/Arch: linux/amd64 wido@wido-desktop:~$