K8s Ingress Controllers

By default, RKE deploys the NGINX ingress controller on all schedulable nodes.

Note: As of v0.1.8, only workers are considered schedulable nodes, but prior to v0.1.8, worker and controlplane nodes were considered schedulable nodes.

RKE will deploy the ingress controller as a DaemonSet with hostnetwork: true, so ports 80, and 443 will be opened on each node where the controller is deployed.

The images used for ingress controller is under the system_images directive. For each Kubernetes version, there are default images associated with the ingress controller, but these can be overridden by changing the image tag in system_images.

Scheduling Ingress Controllers

If you only wanted ingress controllers to be deployed on specific nodes, you can set a node_selector for the ingress. The label in the node_selector would need to match the label on the nodes for the ingress controller to be deployed.

nodes:
- address: 1.1.1.1
  role: [controlplane,worker,etcd]
  user: root
  labels:
    app: ingress

ingress:
  provider: nginx
  node_selector:
    app: ingress

Tolerations

Available as of v1.2.4

The configured tolerations apply to the default-http-backend Deployment.

ingress:
  tolerations:
  - key: "node.kubernetes.io/unreachable"
    operator: "Exists"
    effect: "NoExecute"
    tolerationseconds: 300
  - key: "node.kubernetes.io/not-ready"
    operator: "Exists"
    effect: "NoExecute"
    tolerationseconds: 300

To check for applied tolerations default-http-backend Deployment, use the following commands:

kubectl -n ingress-nginx get deploy default-http-backend -o jsonpath='{.spec.template.spec.tolerations}'

Disabling the Default Ingress Controller

You can disable the default controller by specifying none to the ingress provider directive in the cluster configuration.

ingress:
    provider: none

Configuring NGINX Ingress Controller

For the configuration of NGINX, there are configuration options available in Kubernetes. There are a list of options for the NGINX config map , command line extra_args and annotations.

ingress:
  provider: nginx
  options:
    map-hash-bucket-size: "128"
    ssl-protocols: SSLv2
  extra_args:
    enable-ssl-passthrough: ""

Disabling NGINX Ingress Default Backend

As of v0.20.0, you can disable the default backend service for the ingress controller. This is possible because ingress-nginx will fall back to a local 404 page, and does not require a backend service. The service can be enabled/disabled with a boolean value.

ingress:
  default_backend: false

What happens if the field is omitted? The value of default_backend will default to true. This maintains behavior with older versions of rke. However, a future version of rke will change the default value to false.

Configuring an NGINX Default Certificate

When configuring an ingress object with TLS termination, you must provide it with a certificate used for encryption/decryption. Instead of explicitly defining a certificate each time you configure an ingress, you can set up a custom certificate that’s used by default.

Setting up a default certificate is especially helpful in environments where a wildcard certificate is used, as the certificate can be applied in multiple subdomains.

Prerequisites:

Access to the cluster.yml used to create the cluster.

The PEM encoded certificate you will use as the default certificate.

Obtain or generate your certificate key pair in a PEM encoded form.

Generate a Kubernetes secret from your PEM encoded certificate with the following command, substituting your certificate for mycert.cert and mycert.key.

kubectl -n ingress-nginx create secret tls ingress-default-cert --cert=mycert.cert --key=mycert.key -o yaml --dry-run=true > ingress-default-cert.yaml

Include the contents of ingress-default-cert.yml inline with your RKE cluster.yml file. For example:

addons: |-
  ---
  apiVersion: v1
  data:
    tls.crt: [ENCODED CERT]
    tls.key: [ENCODED KEY]
  kind: Secret
  metadata:
    creationTimestamp: null
    name: ingress-default-cert
    namespace: ingress-nginx
  type: kubernetes.io/tls

Define your ingress resource with the following default-ssl-certificate argument, which references the secret we created earlier under extra_args in your cluster.yml:
```
ingress: 
  provider: "nginx"
  extra_args:
    default-ssl-certificate: "ingress-nginx/ingress-default-cert"
```
Optional: If you want to apply the default certificate to ingresses in a cluster that already exists, you must delete the NGINX ingress controller pods to have Kubernetes schedule new pods with the newly configured extra_args.
```
kubectl delete pod -l app=ingress-nginx -n ingress-nginx
```