We have an existing Traefik v1.7 running on our Docker Swarm cluster and are trying to upgrade to v2.3. V1 to V2 migration tool suggested by Traefik will be able to upgrade the application but currently running ~100 services will need their compose files changed immediately. [Traefik labels needs to be changed]. Instead we planned to install another Traefik instance parallelly on the same cluster and eventually upgrade the compose files to be compatible with v2.3 and remove the instance v1.7.
There were a lot of issues trying to achieve this,
Docker daemon api is insecure. Enabling TLS for outside connection works fine on v1.7 but v2.3 throws issues. [Enabling TLS for outside connections will automatically enable TLS between Traefik and docker daemon for v2.3]. We tried to use [traefik.http.middlewares.secure.forwardauth.tls.insecureSkipVerify=true] but that doesn't work either.
Docker daemon sometimes is confused to pick a Traefik instance between the two versions. So we started adding constraint tags to v2.3 which worked for couple of mins. Later Dashboard seems unresponsive.
Running logs in debug mode isn't helping to figure out the root cause.
Any help to resolve these issues would be great .. Thanks.
Also, I'm curious to know how people have updated the compose files to be compatible to v2.3.? [Updated the Traefik labels as there are no Frontends and Backends anymore]