Traefik Segments #

A true power feature and usually under estimated: (almost) everything with Traefik can be done using labels.

As an application grows, the use of a lot of labels can result in your compose/stack files getter longer (and wider) and they feel a bit messy over time.

A solution to stay on top and to improve readability can be to break up the labels (and rules) into multiple segments. Each segment has a name, hopefully telling future you what is going on.

Example #

Consider the following example:

• one service
• multiple domains are mapped on the service
• for SEO we want to redirect all domains to the final domain

service:
  app:
    image: example/app:v1.0.0
    deploy:
      labels:
        - traefik.enable=true
        - traefik.docker.network=public
        - traefik.port=80
        - traefik.frontend.rule='Host:example.org,foo.example.org,bar.example.org,www.example.org,another-domain.org'
        - traefik.frontend.redirect.regex='https://((foo|bar).example.org|another-domain.org)/(.*)'
        - traefik.frontend.redirect.replacement='https://example.org/$${2}'

Our example uses only five hosts for brevity — consider that there could be a lot more rules.

In order to improve readability and maintainability, we can use multiple segments (or categories):

• a segment called sub-domains to redirect foo.example.org, bar.example.org and www.example.org
• a segment called another to redirect another-domain.org
• a segment called www for the default

service:
  app:
    image: example/app:v1.0.0
    deploy:
      labels:
        - traefik.enable=true
        - traefik.docker.network=public
        - traefik.sub-domains.frontend.rule='Host:foo.example.org,bar.example.org,www.example.org'
        - traefik.sub-domains.frontend.redirect.regex='https://(.*).example.org/(.*)'
        - traefik.sub-domains.frontend.redirect.replacement='https://example.org/$${2}'
        - traefik.sub-domains.port=80
        - traefik.another.frontend.rule='Host:another-domain.org`
        - traefik.another.frontend.redirect.regex='https://another-domain.org/(.*)'
        - traefik.another.frontend.redirect.replacement='https://example.org/$${1}'
        - traefik.another.port=80
        - traefik.www.frontend.rule='Host:example.org'
        - traefik.www.port=80

This is slightly longer, but a lot more readable and extensible. The segments will show up as individual services on your Traefik dashboard. There are virtually no limits to the number of segments a service can have, but consider that adding each segment also has to be maintained by your Traefik loadbalancer.