Saturday, April 13, 2019

Ubuntu 18.04 + Docker Setup

I am setting up a new Docker Engine running on Ubuntu 18.04
During the Ubuntu installation, I selected Docker Engine as part of the deployment setup. By default the Docker Engine Service is run by Snap.

My environment uses web proxy to hit the Internet and internal DNS servers only are allowed. Docker Daemon or Docker Containers must use web proxy and internal DNS to hit the Internet.

To setup Ubuntu with static IP, pointing to the right DNS, netplan must be created
create a YAML file in the /etc/netplan/

> sudo vi /etc/netplan/99-local-init.yaml

version: 2
renderer: networkd
search: [domainlocal.tld]
addresses: [, 10.0.03]

ps: addresses: [,] are the local DNS servers

To get Docker Engine to use web proxy and local DNS servers, Drop-In configuration files must be created. Check the Docker Engine service name under /etc/systemd/system/ folder. My Ubuntu 18.04 installation has got snap.docker.dockerd.service name

Create a folder with the same name of the service name and add ".d" at the end of the folder name

> sudo mkdir -p /etc/systemd/system/snap.docker.dockerd.service.d 

Then you can create as many as .conf files in that folder

To create web proxy configuration

> sudo vi /etc/systemd/system/snap.docker.dockerd.service.d/proxy.conf

Environment="HTTP_PROXY=http://myproxy.domainlocal.tld:8080/" "HTTPS_PROXY=http://myproxy.domainlocal.tld:8080/" "NO_PROXY=localhost,*.domainlocal.tld"

To create DNS setting

> sudo vi /etc/systemd/system/snap.docker.dockerd.service.d/dns.conf

ExecStart=/usr/bin/snap run docker.dockerd --dns --dns --dns-search domainlocal.tld

ps: ExecStart= must be defined in the first line to reset that flag

The daemon must be restarted

> sudo systemtcl daemon-reload
> sudo systemctl restart snap.docker.dockerd

To build / run process within the Docker Container, pass the flags:

> sudo docker build --build-arg http_proxy=http://myproxy.domainlocal.tld:8080 --build-arg https_proxy=http://myproxy.domainlocal.tld:8080 -t dockerhubname/imangename .

Have fun!