Add multiple ingress controller support + traefik

[brandond]

Waiting on:

• Redo watchIngressWithoutClass change rke2-charts#487

---

Proposed Changes

• Add ADR for multiple ingress controller support; initially with traefik as the only additional packaged ingress controller.
• Add CLI flag to select ingress controllers; multiple may be chosen, and --ingress-controller=none will disable all of them, same as --cni=none.
• Update charts

Note: while multiple ingress controllers can be selected via the CLI flag, and the first one will be set as the default ingress class, additional user-provided configuration will be necessary to allow both ingress controllers to run in parallel , due to both charts defaulting to deploying a DaemonSet that binds to ports 80 and 443. For this reason, while allowed by the CLI flag, we will not be supporting parallel installation of multiple ingress controllers.

If someone did want to do it on a cluster with a LoadBalancer controller capable of binding multiple LoadBalancer services on the same ports, something like this would work to reconfigure both controllers to use Deployment+LoadBalancer instead of Daemonset+HostPort:

apiVersion: helm.cattle.io/v1
kind: HelmChartConfig
metadata:
  name: rke2-ingress-nginx
  namespace: kube-system
spec:
  valuesContent: |-
    controller:
      kind: Deployment
      hostPort:
        enabled: false
      service:
        enabled: true
        type: LoadBalancer
---
apiVersion: helm.cattle.io/v1
kind: HelmChartConfig
metadata:
  name: rke2-traefik
  namespace: kube-system
spec:
  valuesContent: |-
    deployment:
      kind: Deployment
    service:
      enabled: true
      type: LoadBalancer
    ports:
      web:
        hostPort: null
      websecure:
        hostPort: null

Types of Changes

ADR; packaged component

Verification

• See linked issue and ADR
• 1. Start rke2 with one or more ingress controllers selected by --ingress-controller flag
  2. Note that selected ingress controller charts are installed and ingressClass resources created.
  3. Note that the first selected ingressClass has annotation ingressclass.kubernetes.io/is-default-class: "true"; others are false or absent.
  4. Note that Ingress resources are picked up by the default ingress controller if the ingressClassName is not set, and the selected ingress controller if ingressClassName is set to one of the installed controller names.

brandond@dev01:~$ kubectl get node -o 'custom-columns=NAME:.metadata.name,NODE-ARGS:metadata.annotations.rke2\.io/node-args'
NAME            NODE-ARGS
rke2-server-1   ["server","--ingress-controller","traefik,ingress-nginx"]

brandond@dev01:~$ kubectl get ingressclass -o 'custom-columns=NAME:.metadata.name,CONTROLLER:.spec.controller,DEFAULT:.metadata.annotations.ingressclass\.kubernetes\.io/is-default-class'
NAME      CONTROLLER                      DEFAULT
nginx     k8s.io/ingress-nginx            <none>
traefik   traefik.io/ingress-controller   true

Testing

Linked Issues

• Support Traefik as ingress for RKE2 #5928

User-Facing Change

Further Comments

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 3.57143% with 54 lines in your changes missing coverage. Please review.

Project coverage is 25.82%. Comparing base (311b3a5) to head (e56bb43).
Report is 3 commits behind head on master.

Files	Patch %	Lines
pkg/cli/cmds/server.go	0.00%	46 Missing ⚠️
pkg/bootstrap/bootstrap.go	0.00%	4 Missing ⚠️
pkg/rke2/rke2_linux.go	50.00%	1 Missing and 1 partial ⚠️
pkg/podexecutor/staticpod.go	0.00%	1 Missing ⚠️
pkg/rke2/rke2.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #5943       +/-   ##
===========================================
+ Coverage    9.77%   25.82%   +16.05%     
===========================================
  Files          32       32               
  Lines        2712     2734       +22     
===========================================
+ Hits          265      706      +441     
+ Misses       2425     1981      -444     
- Partials       22       47       +25     

Flag	Coverage Δ
inttests	9.69% <0.00%> (-0.08%)	⬇️
unittests	18.39% <3.57%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

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[manuelbuil]

I wonder why we need a set instead of a slice. If I understand correclty, the "values" are always slices that we are hardcoding with rke2 components in "pkg/rke2/rke2.go", e.g. CNIItems

[brandond]

I made it a set so that I can easily remove entries from it by value, without having to find their indexes in the slice and elide them. It'd be much more boilerplate code than just the Insert() and Delete() functions that sets provide. I could use a map[string]struct{} and insert/delete keys but generic sets are implemented as a map[comparable]struct{} under the hood anyway:
https://github.com/kubernetes/apimachinery/blob/master/pkg/util/sets/set.go#L24-L25

[manuelbuil]

aaah ok, I was thinking on the property that no copies are possible in sets by default and that did not make sense here. Thanks

[manuelbuil]

I have just realized that if we ever reach this line, something would be broken because windows can never be the server. What if we use this PR to add an error message instead saying that this is not supported?

[brandond]

I wired it up here in case we ever do support windows server nodes. I don't think it needs to be an error, it's just not a code path that is reachable at the moment.