How to configure Traefik 1.7 for wildcard subdomains?

Traefik Traefik v1
1

Hi folks, I am new to Traefik and use it to route my OpenShift URLs.

My question is, how to configure Traefik, so that I do not need to add subdomains in my configs anymore, if a new application was deployed.

Here is my config:

/etc/traefik/traefik.toml

[log]
level = "DEBUG"
[accessLog]

[entryPoints]

[entryPoints.api]
  address = ":6443"

[entryPoints.https]
  address = ":443"

[providers]
[providers.file]
  directory = "/etc/traefik/conf.d"
  watch = true

/etc/traefik/conf.d/exp-ocp.toml

[tcp.routers]
[tcp.routers.exp-ocp4-api]
  entryPoints = ["api"] #entry points are shared among the clusters
  rule = "HostSNI(\`api.exp-ocp4.mycloud.io.cpak\`)"
  service = "service-exp-ocp4-api"
  [tcp.routers.exp-ocp4-api.tls]
  passthrough = true

[tcp.routers.exp-ocp4-https]
  entryPoints = ["https"]
  rule = "HostSNI(\`oauth-openshift.apps.exp-ocp4.mycloud.io.cpak\`,\`console-openshift-console.apps.exp-ocp4.mycloud.io.cpak\`,\`prometheus-k8s-openshift-monitoring.apps.exp-ocp4.mycloud.io.cpak\`,\`grafana-openshift-monitoring.apps.exp-ocp4.mycloud.io.cpak\`,\`alertmanager-main-openshift-monitoring.apps.exp-ocp4.mycloud.io.cpak\`,\`thanos-querier-openshift-monitoring.apps.exp-ocp4.mycloud.io.cpak\`,\`grafana-grafana.apps.exp-ocp4.mycloud.io.cpak\`,\`sso-sso.apps.exp-ocp4.mycloud.io.cpak\`)"
  service = "service-exp-ocp4-https"
  [tcp.routers.exp-ocp4-https.tls]
  passthrough = true

[tcp.services]
[tcp.services.service-exp-ocp4-api.loadBalancer]
[[tcp.services.service-exp-ocp4-api.loadBalancer.servers]]
  address = "#LOADBALANCER_IP#:6443"
[tcp.services.service-exp-ocp4-https.loadBalancer]
[[tcp.services.service-exp-ocp4-https.loadBalancer.servers]]
  address = "#LOADBALANCER_IP#:443"

My goal is to reduce the 'rule' statement in [tcp.routers.exp-ocp4-https] just to

rule = "HostSNI(\`*.apps.exp-ocp4.mycloud.io.cpak\`)"

but it seems a little bit tricky.

Is this possible with Traefik 1.x ?
How the config would looks like in Traefik 2.x ?

Many thanks so far.
Cheers.