You might already know the “cloud native” proxy Traefik from Kubernetes. Or not, as Kubernetes hides most of the configuration from you. But Traefik can be really useful on its own and has a lot of functionality. I find two of its features especially useful for smaller servers ot home servers: the configuration/service discovery and Traefiks ability to resolve and renew Let’s Encrypt certificates.
Traefik Configuration Discovery
Traefik configuration discovery decouples the service configuration from the proxy configuration. Instead of editing a proxy config file every time you want to add a new webpage, you place the configuration at a known source and let Traefik pick it up. This allows for modular deployments where the services that Traefik serves do not have to be known beforehand with minimal downtime of the proxy.
Traefik can watch multiple sources for new configurations of services that it shall act as a proxy for. The service configurations can be read from a file, etcd, Redis and others. One particularly useful variant is the Docker configuration discovery where Traefik reads the configuration from the labels of a running container.
Automatic Lets’t Encrypt certificates with Traefik
Traefik is able to obtain Let’s Encrypt certificates for the domains of your services. When discovering a new configuration, for instance when a docker container starts up, Traefik will check wether SSL is required and how the certificate shall be resolved. If the ACME resolver is selected, Traefik will obtain a SSL certificate for the domain the service will run on and also keep it up to date.
The domain in question has to point to the server that runs Traefik, of course.
The following example shows how to set up Traefik in a Docker container and discover services on the same Docker network, serving them with SSL certificates. I will reuse the jumphost VM created in my guide for Azure VM Deployment With Ansible.
