Docker_Ubuntu-18.04

**1\. Hardcode DNS server in docker daemon.json**

*   Edit `/etc/docker/daemon.json`

        {
            "dns": ["10.1.2.3", "8.8.8.8"]
        }

*   Restart the docker daemon for those changes to take effect:  
     `sudo systemctl restart docker`

*   Now when you run/start a container, docker will populate `/etc/resolv.conf` with the values from `daemon.json`.

* * *

**2\. Fix the hosts's `/etc/resolv.conf`**

**A. Ubuntu 16.04 and earlier**

*   For Ubuntu 16.04 and earlier, `/etc/resolv.conf` was dynamically generated by NetworkManager.

*   Comment out the line `dns=dnsmasq` (with a `#`) in `/etc/NetworkManager/NetworkManager.conf`

*   Restart the NetworkManager to regenerate `/etc/resolv.conf` :  
     `sudo systemctl restart network-manager`

*   Verify on the host: `cat /etc/resolv.conf`

**B. Ubuntu 18.04 and later**

*   Ubuntu 18.04 changed to use [`systemd-resolved` to generate `/etc/resolv.conf`](http://manpages.ubuntu.com/manpages/bionic/man8/systemd-resolved.service.8.html#contenttoc3). Now by default it uses a local DNS cache 127.0.0.53\. That will not work inside a container, so Docker will default to Google's 8.8.8.8 DNS server, which may break for people behind a firewall.

*   `/etc/resolv.conf` is actually a symlink (`ls -l /etc/resolv.conf`) which points to `/run/systemd/resolve/stub-resolv.conf` (127.0.0.53) by default in Ubuntu 18.04.

*   Just change the symlink to point to `/run/systemd/resolve/resolv.conf`, which lists the real DNS servers:  
     `sudo ln -sf /run/systemd/resolve/resolv.conf /etc/resolv.conf`

*   Verify on the host: `cat /etc/resolv.conf`

Now you should have a valid `/etc/resolv.conf` on the host for docker to copy into the containers.

## Install Docker



'

sudo apt-get install bridge-utils
sudo pkill docker
sudo iptables -t nat -F
sudo ifconfig docker0 down
sudo brctl delbr docker0
sudo service docker restart

'

docker-library/busybox#48