Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.

Bug 1457062

Summary: Docker MTU is wrong when SDN is adjusted to smaller MTU
Product: OpenShift Container Platform Reporter: Øystein Bedin <obedin>
Component: InstallerAssignee: Scott Dodson <sdodson>
Status: CLOSED ERRATA QA Contact: Johnny Liu <jialiu>
Severity: high Docs Contact:
Priority: unspecified    
Version: 3.6.0CC: aos-bugs, jokerman, mmccomas, wmeng
Target Milestone: ---   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Starting with OCP 3.4, OpenShift's SDN plugins no longer reconfigure the docker bridge MTU, rather pods are configured properly on creation. Because of this change, non-OpenShift containers may have an MTU configured that is too large to allow access to hosts on the SDN. The installer has been updated to align the MTU setting for the docker bridge with the MTU used inside the cluster, thus avoiding the problem.
 Story Points: ---
Clone Of:
: 1460233 1460235 (view as bug list) Environment:
Last Closed: 2017-08-10 05:26:47 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 1460233, 1460235    

Description Øystein Bedin 2017-05-31 04:01:46 UTC 
Description of problem:
When the OpenShift SDN is smaller than "default", the docker MTU also needs to be adjusted.

Version-Release number of selected component (if applicable):
Found doing a build with the latest OpenShift 3.5

How reproducible:
100%

Steps to Reproduce:
1. Install OpenShift in env where the MTU of the SDN will be adjusted down, e.g.: in an OpenStack environment
2. Observe how some builds are failing, e.g.: a DockerStrategy build with the following source: https://github.com/oybed/test-network
3. Change the docker mtu (add '--mtu=1400' to the /etc/sysconfig/docker-network file) and observe the builds are passing.

Actual results:
Failed builds due to incorrect MTU setting for docker

Expected results:
The installation should have set the docker MTU (just like it does for the SDN) 

Additional info:
Comment 1 Scott Dodson 2017-05-31 21:21:32 UTC 
Proposed fix https://github.com/openshift/openshift-ansible/pull/4336
Comment 2 Scott Dodson 2017-06-05 15:37:44 UTC 
Merged into 3.6, I'll backport to 3.3 - 3.5 once QE verifies this bug.
Comment 3 Scott Dodson 2017-06-05 15:38:38 UTC 
Or 3.4 and 3.5. This change isn't necessary in 3.3 as we reconfigured docker back in the dark ages.
Comment 5 Johnny Liu 2017-06-09 09:35:02 UTC 
Verified this bug with openshift-ansible-3.6.98-1.git.0.e651d65.el7.noarch, and PASS.
# cat /etc/sysconfig/docker-network 
# /etc/sysconfig/docker-network
DOCKER_NETWORK_OPTIONS=' --mtu=1350'

# grep -i mtu /etc/origin/node/node-config.yaml 
   mtu: 1350

# oc new-app https://github.com/oybed/test-network -n install-test

# oc get build -n install-test
NAME                       TYPE      FROM          STATUS     STARTED          DURATION
test-network-1             Docker    Git@71c648f   Complete   51 seconds ago   20s
Comment 7 errata-xmlrpc 2017-08-10 05:26:47 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHEA-2017:1716