IngressRouteTCP object not created when the route is a Service of type ExternalName

[mazzy89]

Do you want to request a feature or report a bug?

Bug

What did you do?

I've created an object of kind: IngressRouteTCP and configured in such way:

apiVersion: traefik.containo.us/v1alpha1
kind: IngressRouteTCP
metadata:
  name: external-tcp-service
spec:
  entryPoints:
    - tcp
  routes:
    - match: HostSNI(`my-external-service.domain.com`)
      services:
        - name: my-external-service
          port: 6379
  tls: {}
---
apiVersion: v1
kind: Service
metadata:
  name: external-tcp-service
spec:
  externalName: internaltcpsrv.domain.local
  type: ExternalName

What did you expect to see?

I would expect that the object external-tcp-service would be created.

What did you see instead?

level=error msg="Cannot create service: service port not found" 

Output of traefik version: (What version of Traefik are you using?)

2.1.3

What is your environment & configuration (arguments, toml, provider, platform, ...)?

Kubernetes 1.15.9

I believe that the reason is of a bug here https://github.com/containous/traefik/blob/master/pkg/provider/kubernetes/crd/kubernetes_tcp.go#L165

There is an immediate lookup of the port in the Service and only after there is a check of the type to verify if the Service is type: ExternalName.

I believe that the logic must be rearranged a bit. I can wire a PR if is needed.

[jbdoumenjou]

Hi @mazzy89,

Could you explain your use case with the ExternalName Service ?

[mazzy89]

Sure. The idea here is to expose a resource specifically an Elasticache cluster that is reachable only from the k8s cluster where Traefik runs.

The k8s Service would proxy internally this resource while IngressRouteTCP would create an entry to expose it publicly.

[mazzy89]

There is anything I can help here? This is blocking us to adopt Traefik v2. I'm open to hearing different approaches

[jbdoumenjou]

You can specify a port on the ExternalName Service to map with the IngressRoute.
However, it could be a good feature to avoid the need of specifying the port on the ExternalName Service by using the IngressRoute service port.

Just a comment on your sample, the name of the service referenced in the IngressRoute does not match the ExternalName Service name.

WDYT ?

[mazzy89]

You can specify a port on the ExternalName Service to map with the IngressRoute.
However, it could be a good feature to avoid the need of specifying the port on the ExternalName Service by using the IngressRoute service port.

I'm going to try by specifying the port in the Service of type ExternalName and see if it works. I was not sure if this is possible. But need definitely to try it.

I like your idea to use the port of the IngressRoute. Personally, it does fit our use case.

Just a comment on your sample, the name of the service referenced in the IngressRoute does not match the ExternalName Service name.

Yeah, that is a typo due to a work of removal of real references from the manifests. 🤓

[mazzy89]

Just tried here. Added to the Service the port having a Service looking like this:

apiVersion: traefik.containo.us/v1alpha1
kind: IngressRouteTCP
metadata:
  name: external-tcp-service
spec:
  entryPoints:
    - redis
  routes:
    - match: HostSNI(`my-external-service.domain.com`)
      services:
        - name: external-tcp-service
          port: 6379
  tls: {}
---
apiVersion: v1
kind: Service
metadata:
  name: external-tcp-service
spec:
  externalName: internaltcpsrv.domain.local
  type: ExternalName
  ports:
    - port: 6379

The result from Traefik logs

+ reverse-proxy-traefikv2-767fd98689-xj2xq › reverse-proxy-traefikv2
reverse-proxy-traefikv2-767fd98689-xj2xq reverse-proxy-traefikv2 time="2020-03-03T14:40:50Z" level=error msg="Cannot create service: service not found" serviceName=external-tcp-service namespace=platform servicePort=6379 providerName=kubernetescrd ingress=external-tcp-service
reverse-proxy-traefikv2-767fd98689-xj2xq reverse-proxy-traefikv2 time="2020-03-03T14:40:50Z" level=error msg="Cannot create service: service not found" servicePort=6379 ingress=external-tcp-service serviceName=external-tcp-service  providerName=kubernetescrd namespace=platform
reverse-proxy-traefikv2-767fd98689-xj2xq reverse-proxy-traefikv2 time="2020-03-03T14:40:51Z" level=error msg="the service \"external-tcp-service-9888b30400de35951949@kubernetescrd\" does not exist" entryPointName=redis routerName=platform-external-tcp-service-9888b30400de35951949@kubernetescrd

[mazzy89]

@jbdoumenjou I was able to replicate the issue and actually the last one the error is just temporary and due to the order that objects are created. Once swapped the order in the manifest, the errors are not reported anymore and the resources look green in the Traefik dashboard.

Need to tests the connection though but at least now Traefik does not complain anymore.

It would be nice to have the feature in place. Do you need help here? Will you go ahead or should I give a try?

[jbdoumenjou]

Thank you, we are working on it. 😄

[mazzy89]

Thank you for the fast reaction here.

[traefiker]

Closed by #6428.