Frequently Asked Question

Adjusting Docker MTU for Virtual Machines
Last Updated 4 months ago

1. Introduction

Post requests via TLS may experience timeouts. This is due to Docker not analyzing the MTU size of the network interfaces on hosts. Virtual networks for our EODC Cloud operate with an MTU of 1450, Docker is not fully compatible by default.

This guide shows how to set Docker's networking to function correctly within these networks.

2. Docker

2.1 Docker OpenStack VM config

Add following line: to the JSON object located at
/etc/docker/daemon.json

N.B This file can be created if it does not already exist.

{
    "mtu": 1450
}

To apply this change it may be necessary to restart the docker daemon. To do this run:

sudo systemctl restart docker

2.1 Docker compose

Docker Compose runs it's own network - so the fix for the Docker daemon does not fix the same issues with Docker Compose. In this case it is necessary to add the following lines in your docker-compose.yml file.

version: '3'
services:
# Add services here...
networks:
  default:
    driver: bridge
    driver_opts:
      com.docker.network.driver.mtu: 1450

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