Allow configuring a default MTU for all containers
All container network interfaces ("vEthernet (Ethernet)") use MTU 1500 by default. There is no way to configure a default MTU other than 1500, despite Docker and Microsoft documentation which indicates that this should be possible: https://docs.microsoft.com/en-us/virtualization/windowscontainers/manage-docker/configure-docker-daemon, https://docs.docker.com/engine/reference/commandline/dockerd/#description.
This is a huge pain point for users running on platforms that require an MTU less than 1500. The only solution at this time is to set the container interface's MTU first thing every time one runs a container, for every container.
David Schott commented
Thank you for raising this, we will evaluate this work, can you please share which platform you are running on? Is this Windows containers on GCE or GKE?
We are evaluating plans for additional platform work in the next Windows release scheduled in holiday 2020 to improve fragmentation support in both l2bridge and WinNAT.