Is it safe to update the Docker bridge IP range on hosts in an RKE or Rancher v2.x launched Kubernetes cluster?
This document (000020203) is provided subject to the disclaimer at the end of this document.
Situation
Question
The docker0
bridge network has a default IP range of 172.17.0.0/16
(with an additional docker-sys
bridge for system-docker using 172.18.0.0/16
by default on RancherOS). These ranges will be routed to these interfaces, per the below example of the route
output. If the range(s) overlap with the internal IP space usage in your own network, the host will not be able to route packets to other hosts in your network that lie within these ranges. As a result you may wish to change the bridge range(s) to enable successful routing to hosts within these.
$ route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
...
172.17.0.0 0.0.0.0 255.255.0.0 U 0 0 0 docker0
...
Pre-requisites
- This article is only applicable to Kubernetes cluster launched by RKE v0.1.x, v0.2.x and v0.3.x, or Rancher v2.x
Answer
Updating the docker0
bridge IP range (and docker-sys
bridge IP range in RancherOS) is possible in an RKE or Rancher v2.x provisioned Kubernetes cluster, where no cluster containers are in fact running attached to the Docker bridge network. The only impact of the change should be some downtime, as you will be required to restart the Docker daemon for the change to take effect.
On RancherOS the bridge IP range (bip
) can be updated for docker and system-docker per the RancherOS documentation on Configuring Docker or System Docker
. You will need to reboot the host for the change to take effect after updating the settings.
For other operating systems, where Docker is installed from the upstream Docker repositories, you should update the bip
configuration in /etc/docker/daemon.json
per the dockerd documentation.
On CentOS 7, RHEL 7 and SLES 12 you should also check the configuration in /etc/sysconfig/docker to ensure --bip
has not been configured there.
Disclaimer
This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.
- Document ID:000020203
- Creation Date: 06-May-2021
- Modified Date:06-May-2021
-
- SUSE Rancher
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