Use kubernetesDNSDomain for all service references

[noam09]

OpenFaaS fails to start in Kubernetes clusters whose base domain is not cluster.local, e.g. cluster2.local.

Expected Behaviour

OpenFaaS should deploy successfully to Kubernetes cluster when kubernetesDNSDomain is set to cluster2.local (i.e. not cluster.local).

Current Behaviour

OpenFaaS is not deployed successfully.
The first sign is that faas-idler enters CrashLoopBackoff state and does not recover.
Other issues arise later on (accessing the GW and so forth), but it's all related to the irregular base domain.

Possible Solution

Use kubernetesDNSDomain in all service references within chart templates.
I've made a few modifications in my branch in a fork which I believe should fix the issue, but they may collide with other features which I haven't tested. I can open a Pull Request if required.

Steps to Reproduce (for bugs)

1. k3d cluster create mycluster
2. kubectl edit configmap -n kube-system coredns

3. + kubernetes cluster2.local in-addr.arpa ip6.arpa {
   - kubernetes cluster.local in-addr.arpa ip6.arpa {

4. kubectl apply -f https://raw.githubusercontent.com/openfaas/faas-netes/master/namespaces.yml
5. helm repo add openfaas https://openfaas.github.io/faas-netes/

6. helm repo update \
     && helm upgrade openfaas --install openfaas/openfaas \
     --namespace openfaas  \
     --set functionNamespace=openfaas-fn \
     --set generateBasicAuth=true \
     --set kubernetesDNSDomain=cluster2.local
   

7. $ kubectl -n openfaas get pods
        NAME                                READY   STATUS             RESTARTS   AGE
        nats-7d86c64647-kv879               1/1     Running            0          3m23s
        queue-worker-596c8949d4-pqnwz       1/1     Running            0          3m23s
        basic-auth-plugin-bc899c574-bzk7s   1/1     Running            0          3m23s
        alertmanager-5475697f88-smfwb       1/1     Running            0          3m23s
        prometheus-697d845647-nhjnw         1/1     Running            0          3m23s
        faas-idler-57bd579645-cql2r         0/1     CrashLoopBackOff   4          3m23s
        gateway-7bf8dd5cd7-8mjlx            2/2     Running            0          3m23s
   

8. $ kubectl -n openfaas logs faas-idler-57bd579645-cql2r
        2020/12/02 04:20:00 cannot connect to OpenFaaS on URL: http://gateway.openfaas:8080
        panic: interface conversion: interface {} is nil, not map[string]interface {}
   
        goroutine 1 [running]:
        main.main()
                /go/src/github.com/openfaas-incubator/faas-idler/main.go:104 +0xa51
   

Context

Attempting to deploy OpenFaaS using Helm to a Kubernetes cluster whose base domain is not cluster.local.

Your Environment

• k3d version:

k3d version v3.3.0
k3s version v1.19.3-k3s3 (default)

• FaaS-CLI version ( Full output from: faas-cli version ):

  ___                   _____           ____
 / _ \ _ __   ___ _ __ |  ___|_ _  __ _/ ___|
| | | | '_ \ / _ \ '_ \| |_ / _` |/ _` \___ \
| |_| | |_) |  __/ | | |  _| (_| | (_| |___) |
 \___/| .__/ \___|_| |_|_|  \__,_|\__,_|____/
      |_|

CLI:
 commit:  35ac0cefa5116ecdeed838726f11d8f99eefdc9d
 version: 0.12.14-2-g35ac0ce
Your faas-cli version (0.12.14-2-g35ac0ce) may be out of date. Version: 0.12.19 is now available on GitHub.

• Docker version docker version (e.g. Docker 17.0.05 ):

Client:
 Version:           19.03.13-ce
 API version:       1.40
 Go version:        go1.15.2
 Git commit:        4484c46d9d
 Built:             Sat Sep 26 12:04:46 2020
 OS/Arch:           linux/amd64
 Experimental:      false

Server:
 Engine:
  Version:          19.03.13-ce
  API version:      1.40 (minimum version 1.12)
  Go version:       go1.15.2
  Git commit:       4484c46d9d
  Built:            Sat Sep 26 12:03:35 2020
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          v1.4.3
  GitCommit:        269548fa27e0089a8b8278fc4fc781d7f65a939b.m
 runc:
  Version:          1.0.0-rc92
  GitCommit:        ff819c7e9184c13b7c2607fe6c30ae19403a7aff
 docker-init:
  Version:          0.18.0
  GitCommit:        fec3683

• What version and distriubtion of Kubernetes are you using? kubectl version

Client Version: version.Info{Major:"1", Minor:"19", GitVersion:"v1.19.4", GitCommit:"d360454c9bcd1634cf4cc52d1867af5491dc9c5f", GitTreeState:"archive", BuildDate:"2020-11-25T13:19:56Z", GoVersion:"go1.15.5", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"19", GitVersion:"v1.19.3+k3s3", GitCommit:"0e4fbfefe1dd8734756dfa4f9ab4fc89665cece4", GitTreeState:"clean", BuildDate:"2020-11-13T07:19:02Z", GoVersion:"go1.15.2", Compiler:"gc", Platform:"linux/amd64"}

• Operating System and version (e.g. Linux, Windows, MacOS):

Arch Linux
Kernel 5.9