Configure Ingress Gateways for Consul on Kubernetes

This page describes how to enable external access through Consul ingress gateways to mesh services running inside Kubernetes. See Ingress Gateways for more information on use-cases and how it works.

Adding an ingress gateway is a multi-step process that consists of the following steps:

• Setting the Helm chart configuration
• Deploying the Helm chart
• Configuring the gateway
• Defining an Intention (if ACLs are enabled)
• Deploying your application to Kubernetes
• Connecting to your application

Setting the helm chart configuration

When deploying the Helm chart you must provide Helm with a custom YAML file that contains your environment configuration.

global:
  name: consul
connectInject:
  enabled: true
ingressGateways:
  enabled: true
  gateways:
    - name: ingress-gateway
      service:
        type: LoadBalancer

The YAML snippet is the launching point for a valid configuration that must be supplied when installing using the official consul-helm chart. Information on additional options can be found in the Helm reference. Configuration options for ingress gateways reside under the ingressGateways entry.

The gateways stanza is where you will define and configure the set of ingress gateways you want deployed to your environment. The only required field for each entry is name, though entries may contain any of the fields found in the defaults stanza. Values in this section override the values from the defaults stanza for the given ingress gateway with one exception: the annotations from the defaults stanza will be appended to any user-defined annotations defined in the gateways stanza rather than being overridden. Please refer to the ingress gateway configuration documentation for a detailed explanation of each option.

Deploying the Helm chart

Ensure you have the latest consul-helm chart and install Consul via helm using the following guide while being sure to provide the yaml configuration as previously discussed.

Configuring the gateway

Now that Consul has been installed with ingress gateways enabled, you can configure the gateways via the IngressGateway custom resource.

Here is an example IngressGateway resource:

apiVersion: consul.hashicorp.com/v1alpha1
kind: IngressGateway
metadata:
  name: ingress-gateway
spec:
  listeners:
    - port: 8080
      protocol: http
      services:
        - name: static-server

Apply the IngressGateway resource with kubectl apply:

$ kubectl apply --filename ingress-gateway.yaml
ingressgateway.consul.hashicorp.com/ingress-gateway created

Since we're using protocol: http, we also need to set the protocol of our service static-server to http. To do that, we create a ServiceDefaults custom resource:

apiVersion: consul.hashicorp.com/v1alpha1
kind: ServiceDefaults
metadata:
  name: static-server
spec:
  protocol: http

Apply the ServiceDefaults resource with kubectl apply:

$ kubectl apply --filename service-defaults.yaml
servicedefaults.consul.hashicorp.com/static-server created

Ensure both resources have synced to Consul successfully:

$ kubectl get servicedefaults
NAME            SYNCED   AGE
static-server   True     45s

$ kubectl get ingressgateway
NAME              SYNCED   AGE
ingress-gateway   True     13m

Viewing the UI

You can confirm the ingress gateways have been configured as expected by viewing the ingress-gateway service instances in the Consul UI.

To view the UI, use the kubectl port-forward command. See Viewing The Consul UI for full instructions.

Once you've port-forwarded to the UI, navigate to the Ingress Gateway instances: http://localhost:8500/ui/dc1/services/ingress-gateway/instances

If TLS is enabled, use https://localhost:8501/ui/dc1/services/ingress-gateway/instances.

Defining an Intention

If ACLs are enabled (via the global.acls.manageSystemACLs setting), you must define an intention to allow the ingress gateway to route to the upstream services defined in the IngressGateway resource (in the example above the upstream service is static-server).

To create an intention that allows the ingress gateway to route to the service static-server, create a ServiceIntentions resource:

apiVersion: consul.hashicorp.com/v1alpha1
kind: ServiceIntentions
metadata:
  name: static-server
spec:
  destination:
    name: static-server
  sources:
    - name: ingress-gateway
      action: allow

Apply the ServiceIntentions resource with kubectl apply:

$ kubectl apply --filename service-intentions.yaml
serviceintentions.consul.hashicorp.com/ingress-gateway created

For detailed instructions on how to configure zero-trust networking with intentions please refer to this guide.

Deploying your application to Kubernetes

Now you will deploy a sample application which echoes "hello world"

apiVersion: v1
kind: Service
metadata:
  name: static-server
spec:
  selector:
    app: static-server
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8080
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: static-server
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: static-server
spec:
  replicas: 1
  selector:
    matchLabels:
      app: static-server
  template:
    metadata:
      name: static-server
      labels:
        app: static-server
      annotations:
        'consul.hashicorp.com/connect-inject': 'true'
    spec:
      containers:
        - name: static-server
          image: hashicorp/http-echo:latest
          args:
            - -text="hello world"
            - -listen=:8080
          ports:
            - containerPort: 8080
              name: http
      serviceAccountName: static-server

$ kubectl apply --filename static-server.yaml

Connecting to your application

You can validate the service is running and registered in the Consul UI by navigating to http://localhost:8500/ui/dc1/services/static-server/instances

If TLS is enabled, use: https://localhost:8501/ui/dc1/services/static-server/instances

You can also validate the connectivity of the application from the ingress gateway using curl:

$ EXTERNAL_IP=$(kubectl get services --selector component=ingress-gateway --output jsonpath="{range .items[*]}{@.status.loadBalancer.ingress[*].ip}{end}")
$ echo "Connecting to \"$EXTERNAL_IP\""
$ curl --header "Host: static-server.ingress.consul" "http://$EXTERNAL_IP:8080"
"hello world"

To delete the ingress gateway, set enabled to false in your Helm configuration:

global:
  name: consul
connectInject:
  enabled: true
ingressGateways:
  enabled: false # Set to false
  gateways:
    - name: ingress-gateway
      service:
        type: LoadBalancer

And run Helm upgrade:

$ helm upgrade consul hashicorp/consul --values values.yaml