docker - change default bridge netowrk

docker-bridge-notes.txt

Docker defauilts to taking over netowrks 172.17.0.0.  
If this conflicts with other tools such as a VPN which you cannot control, 
you can change the default bridge.   This is easier if you have never started docker.
You wouldnt be reading this if that were the case.
So how to get out of the mess ?

# Bug reports / rfc
https://github.com/docker/docker/issues/8696

# Set the ip of the Docker bridge with Systemd
http://container-solutions.com/set-the-ip-of-the-docker-bridge-with-systemd/

##
## summary 

Stop docker 
Remove every vestage of its network leftovers
Change the startup paramaters to use a new network
#Pray #Profit

## Centos/Fedora/RH 7 example
# as root - no silly sudo stuff for kids

yum install bridge-utils
ip link set docker0 down
brctl delbr docker0

## make sure its gone
route

# add a -bip entry to wherever it is you configure docker
# /etc/systemd/system/docker.service.d/fix-bridge.conf
Add:  --bip="172.218.0.0/16" 

Might look like this


[Service]
ExecStart=
ExecStart=/usr/bin/docker -d -H fd:// --bip=172.218.0.0/16

Or really ugly like  mine

[Service]
ExecStart=
ExecStart=/usr/bin/dockerd -H tcp://0.0.0.0:2376 -H unix:///var/run/docker.sock --storage-driver overlay2 --tlsverify --tlscacert /etc/docker/ca.pem --tlscert /etc/docker/server.pem --tlskey /etc/docker/server-key.pem --label provider=generic --insecure-registry nas:5000  --bip="172.30.0.0/16"  

MountFlags=slave
LimitNOFILE=1048576
LimitNPROC=1048576
LimitCORE=infinity
Environment=

-------

ITS A LIE ---  IT DOESNT WORK IF YOU SET a CIDR that ends in 0 !!!!

https://success.docker.com/Datacenter/Solve/How_do_I_configure_the_default_bridge_(docker0)_network_for_Docker_Engine_to_a_different_subnet%3F

This works
ExecStart=/usr/bin/dockerd .. --bip=172.30.0.1/16

Note it ends in 1 not 0 !!

Thank you!