Docker, Traefik and dnsmasq
If you have ever been in the situation that need more than one local http service running on your local machine and reachable with a DNS rather than different ports, this setup might be interesting for you.
dnsmasq is a light DNS forwarder, which proves to be very useful in the use case described here. Traefik is a fast, modern HTTP reverse proxy and load balancer perfectly designed for Docker (impressive work).
The setup we are trying to have here is the following:
- One web application named "whoami" will be available as http://whoami.docker.localhost
- One web application named "whoami2" will be available as http://whoami2.docker.localhost
- If I add a new one, I don't want to have to edit /etc/hosts
We'll see how to configure them.
Configuration of dnsmasq
Install dnsmasq if needed
sudo apt install dnsmasq
Active dnsmasq for listening requests from localhost, edit /etc/dnsmasq.conf and ensure you have this line
listen-address=127.0.0.1
Configure your domain by creating a file /etc/dnsmasq.d/localhost.conf containing
address=/localhost/127.0.0.1
Which means that all requests to any subdomain of .localhost will be forwarded to 127.0.0.1
Edit /etc/dhcp/dhclient.conf and uncomment the following line, so the DHCP client will use the local dnsmasq forwarder.
prepend domain-name-servers 127.0.0.1;
Restart dnsmasq, active it to start automatically
systemctl restart dnsmasq systemctl enable dnsmasq
And apply the new DHCP config
dhclient
Using Traefik in a docker-compose configuration
version: '2'
services:
whoami:
image: emilevauge/whoami
labels:
- "traefik.frontend.rule=Host:whoami.docker.localhost"
whoami2:
image: emilevauge/whoami
labels:
- "traefik.frontend.rule=Host:whoami2.docker.localhost"
traefik:
image: traefik
command: --api --docker #Enables the web UI and tells Træfik to listen to docker
ports:
- "80:80" #The HTTP port
- "8080:8080" #The Web UI (enabled by --api)
volumes:
- /var/run/docker.sock:/var/run/docker.sock #So that Traefik can listen to the Docker events
Start it with
docker-compose up
Now heads on http://whoami.docker.localhost/ and http://whoami2.docker.localhost/, hurray!
Oh, and the icing on the cake, open the Traefik dashboard on http://localhost:8080. You should see the whoamis frontends and backends listed.
You could also start only one traefik container globally on your machine, but then you would have to share a network with your docker-compose composition.