Support Traefik in Cluster Mode (HA)

[ralphg6]

Based on https://docs.traefik.io/user-guide/cluster/

[flaviostutz]

Haha! What's the difference between an HA+LB Traefik and simply launching multiple instances of Traefik load balanced by Swarm itself? The difference is only on Let's Encrypt capabilities of sharing the TLS certificate?

[ralphg6]

As the documentation explains:

In cluster mode, ACME certificates have to be stored in a KV Store entry.

Thanks to the Træfik cluster mode algorithm (based on the Raft Consensus Algorithm), only one instance will contact Let's encrypt to solve the challenges.

The others instances will get ACME certificate from the KV Store entry.

Therefore, the main motivation is ACME. If it is not enabled, it does not make sense since it makes the LB between Traefiks dependent on an external solution.

In addition, another advantage is that, all configuration is centralized in the KV Store. This fact does not have as much force in this project, since the configuration is in a stack, generated from a compose file. So to update it would be enough to update the stack.

[flaviostutz]

Haven't you thought about creating a Let's Encrypt certificate per Traefik instance so we can simplify our deployment?