defaultRule to get the service name without the stack

Traefik Traefik v2 (latest)
,
1

I want an automatic rule that goes something like

stack == intranet

service is whoami in the docker-compose.yml which yields intranet_whoami as the service name.

I sort of want it to yield PathPrefix('/whoami') without being explicitly set.

Any suggestions on how to set up the rule?

The rule I think would look something like this

{{ .ServiceName | replace .StackName \"\" }}

The data is in the labels

       "Labels": {
                "com.docker.stack.namespace": "intranet",
                "com.docker.swarm.node.id": "qosf0b21u821yqgxr4tvmabqi",
                "com.docker.swarm.service.id": "chgy8u0kf9n1qr2fbwgjl5dyk",
                "com.docker.swarm.service.name": "intranet_whoami",
                "com.docker.swarm.task": "",
                "com.docker.swarm.task.id": "6dgsqlz7zsdg1yovbgtyuvna6",
                "com.docker.swarm.task.name": "intranet_whoami.1.6dgsqlz7zsdg1yovbgtyuvna6"
            }

{{ .ServiceName | replace (index .Labels \"com.docker.stack.namespace\") \"\" }}
1 Like
2 
labels:
  - '--providers.docker.defaultrule=Host(`{{ index .Labels "com.docker.swarm.service.name" | trimPrefix (index .Labels "com.docker.stack.namespace") | trimPrefix "_" }}.docker.localhost`)'

labels:
  - '--providers.docker.defaultrule=PathPrefix(`/{{ index .Labels "com.docker.swarm.service.name" | trimPrefix (index .Labels "com.docker.stack.namespace") | trimPrefix "_" }}`)'

Note:

  • I use simple quote ' to "wrap" the label
  • I use double qoutes " for the strings

Doc:

1 Like
3

OK I like yours better than what I eventually ended up with

- "--providers.docker.defaultRule={{ substr (int ( add (len (index .Labels `com.docker.stack.namespace`)) 1)) 9999 .Name }}"

Minor correction though, I wanted the path Prefix, so I am using

- '--providers.docker.defaultrule=PathPrefix(`/{{ .Name | trimPrefix (index .Labels "com.docker.stack.namespace") | trimPrefix "_" }}`)'

Note I used .Name which is the service name according to the documentation.

So my final setup is

  whoami:
    image: containous/whoami
    deploy:
      resources:
        limits:
          cpus: '0.5'
          memory: 32M
      labels:
        - intranet=true
        - traefik.enable=true
        # - traefik.http.routers.whoami.rule=Path(`/whoami`)
        # - traefik.http.routers.whoami.entryPoints=http
        # - traefik.http.routers.whoami.middlewares=default
        # - traefik.http.routers.whoami.service=ping
        - traefik.http.services.whoami.loadbalancer.server.port=80
    networks:
      - intranet
4

Something seems to have changed in 2.0.1 this seems to put - instead of _ now. My workaround for now is to add trimPrefix "_" | trimPrefix "-" so it will work with both 2.0.0 and 2.0.1

1 Like
5

Unless you want to get crazy trying to understand why the suggest approach doesn't work, use the normalize function to get rid of underscore to hypen conversions applied by docker:

 - --providers.docker.defaultRule=Host(`example.com`) && PathPrefix(`/{{ ( .Name | trimPrefix (normalize (index .Labels "com.docker.stack.namespace") ) | trimPrefix "-" )  }}`)