Ingress Gateways on Kubernetes

1.8.0+: This feature is available in Consul versions 1.8.0 and higher

This topic requires familiarity with Ingress Gateways.

This page describes how to enable external access to Connect service mesh services running inside Kubernetes using Consul ingress gateways. 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.

  1. global:
  2.   name: consul
  3. connectInject:
  4.   enabled: true
  5. ingressGateways:
  6.   enabled: true
  7.   gateways:
  8.     - name: ingress-gateway
  9.       service:
  10.         type: LoadBalancer

Note: this will create a public unauthenticated LoadBalancer in your cluster, please take appropriate security considerations.

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.

Note: Make sure any ports that will be used as listeners in the ingress gateway’s Consul config entry are included in the ports object for each gateway. By default ports 8080 and 8443 are exposed for traffic.

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 must add the corresponding configuration to Consul. This requires you to use the Consul CLI. Configuring the ingress gateway requires:

  • Accessing the Consul server
  • Submitting an Ingress Gateway configuration entry to Consul

Accessing the Consul server

You can access the Consul server directly from your host via kubectl port-forward, this is helpful for interacting with the Consul UI locally as well as validating connectivity of the application.

  1. $ kubectl port-forward consul-server-0 8500 &

If TLS is enabled use port 8501.

Download the latest Consul binary from Downloads. https://releases.hashicorp.com/consul/

If TLS is enabled set:

  1. $ export CONSUL_HTTP_ADDR=https://localhost:8501

If ACLs are enabled set :

  1. $ export CONSUL_HTTP_TOKEN=$(kubectl get secret consul-bootstrap-acl-token -o jsonpath={.data.token} | base64 -D)
  2. $ export CONSUL_HTTP_SSL_VERIFY=false

Submitting an Ingress Gateway configuration entry

Now that you have access to a Consul server through the forwarded port and you have the Consul CLI configured locally, you are able to submit an ingress gateway configuration entry. Here is an ingress gateway configuration.

  1. Kind = "ingress-gateway"
  2. Name = "ingress-gateway"
  4. Listeners = [
  5.  {
  6.    Port = 8080
  7.    Protocol = "http"
  8.    Services = [
  9.      {
  10.        Name = "static-server"
  11.      }
  12.    ]
  13.  }
  14. ]

Submit the ingress gateway configuration with the Consul CLI using this command.

  1. $ consul config write ingress-gateway.hcl

You can confirm the ingress gateways have been configured as expected by viewing the ingress-gateway service instances in the Consul UI: http://localhost:8500/ui/dc1/services/ingress-gateway/.

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

Defining an Intention

If ACLs are enabled, you must define an intention to allow the ingress gateway to access the upstream services defined in the config entry.

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

  1. $ consul intention create ingress-gateway static-server

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”

  1. apiVersion: v1
  2. kind: ServiceAccount
  3. metadata:
  4.   name: static-server
  5. ---
  6. apiVersion: v1
  7. kind: Pod
  8. metadata:
  9.   name: static-server
  10.   annotations:
  11.     'consul.hashicorp.com/connect-inject': 'true'
  12. spec:
  13.   containers:
  14.     # This name will be the service name in Consul.
  15.     - name: static-server
  16.       image: hashicorp/http-echo:latest
  17.       args:
  18.         - -text="hello world"
  19.         - -listen=:8080
  20.       ports:
  21.         - containerPort: 8080
  22.           name: http
  23.     # If ACLs are enabled, the serviceAccountName must match the Consul service name.
  24.   serviceAccountName: static-server
  1. $ kubectl apply -f 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:

  1. $ EXTERNAL_IP=$(kubectl get services | grep ingress-gateway | awk ‘{print $4}’)
  2. $ curl -H "Host: static-server.ingress.consul" $EXTERNAL_IP:8080

Security Warning: Please be sure to delete the application and services created here as they represent a security risk through leaving an open and unauthenticated load balancer alive in your cluster.

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

  1. global:
  2.   name: consul
  3. connectInject:
  4.   enabled: true
  5. ingressGateways:
  6.   enabled: false # Set to false
  7.   gateways:
  8.     - name: ingress-gateway
  9.       service:
  10.         type: LoadBalancer

And run Helm upgrade:

  1. $ helm upgrade consul hashicorp/consul -f config.yaml