»Configuring Ingress Controllers with Consul on Kubernetes

This topic requires familiarity with Ingress Controllers

The following information requires Consul 1.10+, Consul-k8s 0.26+, Consul-helm 0.32+ configured with Transparent Proxy mode enabled.

This page describes a general approach for integrating Ingress Controllers with Consul on Kubernetes to secure traffic from the Controller to the backend services. This allows Consul to transparently secure traffic from the ingress point through the entire traffic flow of the service.

A few steps are generally required to enable an Ingress controller to join the mesh and pass traffic through to a service:

Enable connect-injection via an annotation on the Ingress Controller's deployment: consul.hashicorp.com/connect-inject is true.
Using the following annotations on the Ingress controller's deployment, set up exclusion rules for its ports.
- consul.hashicorp.com/transparent-proxy-exclude-inbound-ports - Provides the ability to exclude a list of ports for inbound traffic that the service exposes from redirection. Typical configurations would require all inbound service ports for the controller to be included in this list.
- consul.hashicorp.com/transparent-proxy-exclude-outbound-ports - Provides the ability to exclude a list of ports for outbound traffic that the service exposes from redirection. These would be outbound ports used by your ingress controller which expect to skip the mesh and talk to non-mesh services.
- consul.hashicorp.com/transparent-proxy-exclude-outbound-cidrs - Provides the ability to exclude a list of CIDRs that the service communicates with for outbound requests from redirection. It is somewhat common that an Ingress controller will expect to make API calls to the Kubernetes service for service/endpoint management. As such including the ClusterIP of the Kubernetes service is common.

Note: Depending on which ingress controller you use, these stanzas may differ in name and layout, but it is important to apply these annotations to the pods of your ingress controller.

# An example list of pod annotations for an ingress controller, which need be applied to PODS for the controller, not the deployment itself.
  podAnnotations:
    consul.hashicorp.com/connect-inject: "true"
    # Add the container ports used by your ingress controller
    consul.hashicorp.com/transparent-proxy-exclude-inbound-ports: "80,8000,9000,8443"
    # And the CIDR of your Kubernetes API: `kubectl get svc kubernetes -o jsonpath='{.spec.clusterIP}'
    consul.hashicorp.com/transparent-proxy-exclude-outbound-cidrs: "10.108.0.1/32"

# An example list of pod annotations for an ingress controller, which need be applied to PODS for the controller, not the deployment itself.  podAnnotations:    consul.hashicorp.com/connect-inject: "true"    # Add the container ports used by your ingress controller    consul.hashicorp.com/transparent-proxy-exclude-inbound-ports: "80,8000,9000,8443"    # And the CIDR of your Kubernetes API: `kubectl get svc kubernetes -o jsonpath='{.spec.clusterIP}'    consul.hashicorp.com/transparent-proxy-exclude-outbound-cidrs: "10.108.0.1/32"

If the Ingress controller acts as a LoadBalancer and routes directly to Pod IPs instead of the ClusterIP of your Kubernetes Services a ServiceDefault CRD must be applied to each backend service allowing it to use the dialedDirectly features. By default this is disabled.

# Example Service defaults config entry
apiVersion: consul.hashicorp.com/v1alpha1
kind: ServiceDefaults
metadata:
  name: backend
spec:
  transparentProxy:
    dialedDirectly: true

# Example Service defaults config entryapiVersion: consul.hashicorp.com/v1alpha1kind: ServiceDefaultsmetadata:  name: backendspec:  transparentProxy:    dialedDirectly: true

An intention from the Ingress Controller to the backend application must also be applied, this could be an L4 or L7 intention:

# example L4 intention, but an L7 intention can also be used to control access to specific routes.
apiVersion: consul.hashicorp.com/v1alpha1
kind: ServiceIntentions
metadata:
  name: ingress-backend
spec:
  destination:
    name: backend
  sources:
    - name: ingress
      action: allow

# example L4 intention, but an L7 intention can also be used to control access to specific routes.apiVersion: consul.hashicorp.com/v1alpha1kind: ServiceIntentionsmetadata:  name: ingress-backendspec:  destination:    name: backend  sources:    - name: ingress      action: allow

»Common Configuration Problems:

The Ingress Controller's ServiceAccount name and Service name differ by default in some platforms. Consul on Kubernetes requires the ServiceAccount and Service to have the same name. To resolve this be sure to explicitly set ServiceAccount name the same as the ingress controller service name using it's respective helm configurations.
If the Ingress Controller does not have the correct inbound ports excluded it will fail to start and the Ingress' service will not get created, causing the controller to hang in the init container. The required container ports are not always readily available in the helm charts, so in order to resolve this examine the ingress controller's underlying pod spec and look for the required container ports, adding these to the consul.hashicorp.com/transparent-proxy-exclude-inbound-ports annotation on the ingress controller deployment.

»Examples:

Here are a couple example configurations which can be used as reference points in setting up your own ingress controller configuration! These were used in dev environments and are not intended to be fully supported but should provide some idea how to extend the information above to your own uses cases.