Connect an Elastic Kubernetes Service Cluster to HCP Consul

HashiCorp Cloud Platform (HCP) is a fully managed platform offering HashiCorp Products as a Service (HPaaS) to automate infrastructure on any cloud.

This tutorial will cover the process required to connect an EKS Cluster to HCP Consul on AWS.

»Prerequisites

The following prerequisites are required:

An HCP HashiCorp Virtual Network (HVN)
An HCP Consul deployment
AWS CLI
kubectl
helm
jq
git
An EKS Cluster deployed in the VPC associated with your HVN

For this tutorial, you will need to ensure that you have authenticated with the AWS CLI, and that the CLI is targeting the region where you have created your EKS cluster. Review the AWS documentation for instructions on how to configure the AWS CLI.

To ensure that communication between your HCP Consul cluster servers and the client agent running in your EKS cluster is possible, you must complete the steps detailed in either the manual deployment or in the Terraform deployment tutorial. It is also mandatory that your AWS EKS cluster is deployed in the VPC that has been associated with your HVN. Otherwise, there will not be a configured peering connection, and the control plane running on the HCP Consul cluster servers will not be able to communicate with the data plane provided by the client agents that you will be installing to the EKS cluster.

»Configure development host

Kubernetes stores cluster connection information in a special file called kubeconfig. You can retrieve the Kubernetes configuration settings for your EKS cluster and merge them into your local kubeconfig file by issuing the following command.

$ aws eks --region [your-region] update-kubeconfig --name [your-cluster-name]

$ aws eks --region [your-region] update-kubeconfig --name [your-cluster-name]

You can use the HCP Portal to retrieve the client configuration information you need to connect your EKS cluster client agents to your Consul cluster. Navigate to the Consul resource page in the HCP portal, and then select the Consul cluster you want to join your EKS cluster client agents to. Click the Access Consul dropdown and then select Download to install Client Agents to download a zip archive that contains the necessary files to join your client agents to the cluster. The archive includes a default client configuration and certificate. Both should be considered secrets, and should be kept in a secure location.

Unzip the client config package into the current working directory, and then use ls to confirm that both the client_config.json and ca.pem files are available.

$ ls
ca.pem             client_config.json

$ ls
ca.pem             client_config.json

From the same Access Consul dropdown in the HCP UI, select Generate admin token and then click copy icon from the dialog box. A global-management root token is now in your clipboard. Set this token to the CONSUL_HTTP_TOKEN environment variable on your development host so that you can reference it later in the tutorial.

$ export CONSUL_HTTP_TOKEN=[your-token]

$ export CONSUL_HTTP_TOKEN=[your-token]

Create a consul namespace in your Kubernetes cluster. Your Consul secrets and resources will be created in this namespace.

$ kubectl create namespace consul
namespace/consul created

$ kubectl create namespace consul
namespace/consul created

»Configure Consul secrets

Consul Service on HCP is secure by default. This means that client agents will need to be configured with the gossip encryption key, the Consul CA cert, and a root ACL token. All three of these secrets will need to be stored in the Kubernetes secrets engine so that they can be referenced and retrieved during the helm chart installation.

Use the ca.pem file in the current directory to create a Kubernetes secret to store the Consul CA certificate.

$ kubectl create secret generic "consul-ca-cert" --from-file='tls.crt=./ca.pem' --namespace consul
secret/consul-ca-cert created

$ kubectl create secret generic "consul-ca-cert" --from-file='tls.crt=./ca.pem' --namespace consul
secret/consul-ca-cert created

The Consul gossip encryption key is embedded in the client_config.json file that you downloaded and extracted into your current directory. Issue the following command to create a Kubernetes secret that stores the Consul gossip key encryption key. The following command uses jq to extract the value from the client_config.json file.

$ kubectl create secret generic "consul-gossip-key" --from-literal="key=$(jq -r .encrypt client_config.json)" --namespace consul
secret/consul-gossip-key created

$ kubectl create secret generic "consul-gossip-key" --from-literal="key=$(jq -r .encrypt client_config.json)" --namespace consul
secret/consul-gossip-key created

The last secret you need to add is an ACL bootstrap token. You can use the one you set to your CONSUL_HTTP_TOKEN environment variable earlier. Issue the following command to create a Kubernetes secret to store the bootstrap ACL token.

Note: If you are configuring a production environment, you should create a client token with a minimum set of privileges. For an in depth review of how to configure ACLs for Consul, refer to the Secure Consul with Access Control Lists tutorial or the official documentation.

$ kubectl create secret generic "consul-bootstrap-token" --from-literal="token=${CONSUL_HTTP_TOKEN}" --namespace consul
secret/consul-bootstrap-token created

$ kubectl create secret generic "consul-bootstrap-token" --from-literal="token=${CONSUL_HTTP_TOKEN}" --namespace consul
secret/consul-bootstrap-token created

»Install Consul on EKS

Extract some more configuration values from the client_config.json file and set them to environment variables that can be used to generate your Helm values file. Issue the following command to set the DATACENTER environment variable.

$ export DATACENTER=$(jq -r .datacenter client_config.json)

$ export DATACENTER=$(jq -r .datacenter client_config.json)

Extract the private server URL from the client config so that it can be set in the Helm values file as the externalServers:hosts entry. This value will be passed as the retry-join option to the Consul clients.

$ export RETRY_JOIN=$(jq -r --compact-output .retry_join client_config.json)

$ export RETRY_JOIN=$(jq -r --compact-output .retry_join client_config.json)

Extract the public server URL from the client config so that it can be set the Helm values file as the k8sAuthMethodHost entry.

Note: The following script relies on your cluster matching your current-context name. If you have created an alias for your context, or the current-context name does not match the cluster name for any other reason, you must manually set the KUBE_API_URL to the API server URL of your EKS cluster. You can use kubectl config view to view your cluster, and retrieve API server URL.

$ export KUBE_API_URL=$(kubectl config view -o jsonpath="{.clusters[?(@.name == \"$(kubectl config current-context)\")].cluster.server}")

$ export KUBE_API_URL=$(kubectl config view -o jsonpath="{.clusters[?(@.name == \"$(kubectl config current-context)\")].cluster.server}")

Validate that all of your environment variables have been set.

$ echo $DATACENTER && \
  echo $RETRY_JOIN && \
  echo $KUBE_API_URL

$ echo $DATACENTER && \
  echo $RETRY_JOIN && \
  echo $KUBE_API_URL

Example output:

dc1
["learn-hcp-eks-cluster.private.consul.00000000-0000-0000-0000-000000000000.aws.hashicorp.cloud"]
https://000000000000.gr7.us-west-2.eks.amazonaws.com

dc1
["learn-hcp-eks-cluster.private.consul.00000000-0000-0000-0000-000000000000.aws.hashicorp.cloud"]
https://000000000000.gr7.us-west-2.eks.amazonaws.com

Note: If any of these environment variables are not correctly set, the following script will generate an incomplete Helm values file, and the Consul Helm installation will not succeed.

Generate the Helm values file. Note that this configuration sets up an ingress gateway. This will be covered in more depth later.

Warning: The value for the global.name configuration must be unique for each Kubernetes cluster where Consul clients are installed and configured to join Consul as a shared service, such as HCP Consul. You can change the global name through the global.name value in the Helm chart.

How you install Consul Clients depends on your HCP Consul Cluster:

To install clients on a single Consul cluster, choose the Single Consul Cluster tab.
To install clients on a primary or secondary Consul cluster that is part of a federated environment, select the Federated Consul Cluster tab.

$ cat > config.yaml << EOF
global:
  name: consul
  enabled: false
  datacenter: ${DATACENTER}
  acls:
    manageSystemACLs: true
    bootstrapToken:
      secretName: consul-bootstrap-token
      secretKey: token
  gossipEncryption:
    secretName: consul-gossip-key
    secretKey: key
  tls:
    enabled: true
    enableAutoEncrypt: true
    caCert:
      secretName: consul-ca-cert
      secretKey: tls.crt
  enableConsulNamespaces: true
externalServers:
  enabled: true
  hosts: ${RETRY_JOIN}
  httpsPort: 443
  useSystemRoots: true
  k8sAuthMethodHost: ${KUBE_API_URL}
client:
  enabled: true
  join: ${RETRY_JOIN}
connectInject:
  enabled: true
controller:
  enabled: true
ingressGateways:
  enabled: true
  defaults:
    replicas: 1
  gateways:
    - name: ingress-gateway
      service:
        type: LoadBalancer
EOF

1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839404142$ cat > config.yaml << EOF
global:
  name: consul
  enabled: false
  datacenter: ${DATACENTER}
  acls:
    manageSystemACLs: true
    bootstrapToken:
      secretName: consul-bootstrap-token
      secretKey: token
  gossipEncryption:
    secretName: consul-gossip-key
    secretKey: key
  tls:
    enabled: true
    enableAutoEncrypt: true
    caCert:
      secretName: consul-ca-cert
      secretKey: tls.crt
  enableConsulNamespaces: true
externalServers:
  enabled: true
  hosts: ${RETRY_JOIN}
  httpsPort: 443
  useSystemRoots: true
  k8sAuthMethodHost: ${KUBE_API_URL}
client:
  enabled: true
  join: ${RETRY_JOIN}
connectInject:
  enabled: true
controller:
  enabled: true
ingressGateways:
  enabled: true
  defaults:
    replicas: 1
  gateways:
    - name: ingress-gateway
      service:
        type: LoadBalancer
EOF

Validate that the config file is populated correctly.

$ more config.yaml

$ more config.yaml

»Deploy Consul

Now that you have customized your config.yaml file, you can deploy Consul with Helm or the Consul K8S CLI. We recommend you deploy Consul into its own dedicated namespace as shown below. This should only take a few minutes. The Consul pods should appear in the pod list immediately.

Tip: HashiCorp Cloud Platform offers Enterprise features. To interact with these features, you need to install the Enterprise Consul binary for your client agents. Learn more information about Consul Enterprise and the Helm Chart in the Consul Enterprise Helm Chart documentation.

$ helm repo add hashicorp https://helm.releases.hashicorp.com
"hashicorp" has been added to your repositories

$ helm repo add hashicorp https://helm.releases.hashicorp.com
"hashicorp" has been added to your repositories

$ helm install consul hashicorp/consul --values config.yaml --namespace consul --version "0.43.0" --set global.image=hashicorp/consul-enterprise:1.12.0-ent

$ helm install consul hashicorp/consul --values config.yaml --namespace consul --version "0.43.0" --set global.image=hashicorp/consul-enterprise:1.12.0-ent

Note: You can review the official Helm chart values to learn more about the default settings.

To check the deployment process on the command line you can use kubectl get pods.

$ kubectl get pods --namespace consul
NAME                                           READY   STATUS    RESTARTS   AGE
consul-client-lqfg2                            1/1     Running   0          74s
consul-client-n2bgm                            1/1     Running   0          74s
consul-client-r7kq6                            1/1     Running   0          74s
consul-connect-injector-67498ddc87-5z9jh       1/1     Running   0          74s
consul-connect-injector-67498ddc87-85q2g       1/1     Running   0          74s
consul-controller-66dbfd4f77-l59dp             1/1     Running   0          74s
consul-ingress-gateway-584dcbc5bd-xfbcj        2/2     Running   0          74s
consul-webhook-cert-manager-7cf6df6c4f-tbx82   1/1     Running   0          74s

$ kubectl get pods --namespace consul
NAME                                           READY   STATUS    RESTARTS   AGE
consul-client-lqfg2                            1/1     Running   0          74s
consul-client-n2bgm                            1/1     Running   0          74s
consul-client-r7kq6                            1/1     Running   0          74s
consul-connect-injector-67498ddc87-5z9jh       1/1     Running   0          74s
consul-connect-injector-67498ddc87-85q2g       1/1     Running   0          74s
consul-controller-66dbfd4f77-l59dp             1/1     Running   0          74s
consul-ingress-gateway-584dcbc5bd-xfbcj        2/2     Running   0          74s
consul-webhook-cert-manager-7cf6df6c4f-tbx82   1/1     Running   0          74s

»Deploy an example workload

Now that the clients have been deployed, it is time to deploy an application workload. This tutorial will use the HashiCups demo application. Issue the following command to clone the repository to the development host.

$ git clone https://github.com/hashicorp/learn-consul-kubernetes.git

$ git clone https://github.com/hashicorp/learn-consul-kubernetes.git

Now, checkout the tagged version verified for this tutorial.

$ git checkout tags/v0.0.6

$ git checkout tags/v0.0.6

Change directory into the example repository.

$ cd learn-consul-kubernetes/consul-client-eks

$ cd learn-consul-kubernetes/consul-client-eks

The repository contains the necessary yaml files to deploy the application. Issue the following command to deploy the application to your EKS cluster.

$ kubectl apply -f ./hashicups

$ kubectl apply -f ./hashicups

Example output:

service/frontend created
serviceaccount/frontend created
configmap/nginx-configmap created
deployment.apps/frontend created
service/product-api-service created
serviceaccount/product-api created
configmap/db-configmap created
deployment.apps/product-api created
service/postgres created
serviceaccount/postgres created
deployment.apps/postgres created
service/public-api created
serviceaccount/public-api created
deployment.apps/public-api created
serviceintentions.consul.hashicorp.com/ingress-gateway-to-frontend created
serviceintentions.consul.hashicorp.com/frontend-to-public-api created
serviceintentions.consul.hashicorp.com/public-api-to-product-api created
serviceintentions.consul.hashicorp.com/product-api-to-postgres created

service/frontend created
serviceaccount/frontend created
configmap/nginx-configmap created
deployment.apps/frontend created
service/product-api-service created
serviceaccount/product-api created
configmap/db-configmap created
deployment.apps/product-api created
service/postgres created
serviceaccount/postgres created
deployment.apps/postgres created
service/public-api created
serviceaccount/public-api created
deployment.apps/public-api created
serviceintentions.consul.hashicorp.com/ingress-gateway-to-frontend created
serviceintentions.consul.hashicorp.com/frontend-to-public-api created
serviceintentions.consul.hashicorp.com/public-api-to-product-api created
serviceintentions.consul.hashicorp.com/product-api-to-postgres created

»Register a Consul ingress gateway

In Consul, an ingress gateway is a kind of resources called a Config Entry. An ingress gateway is an endpoint that allows external traffic to reach specific resources, such as the application user interface, that are hosted within the datacenter.

Use the following command to create a file named ingress-gateway.yaml. You will use this to register an ingress gateway with Consul. Notice the Name value matches the ingressGateways:gateways:name entry in config.yaml. These fields must match.

$ cat > ingress-gateway.yaml << EOF
apiVersion: consul.hashicorp.com/v1alpha1
kind: IngressGateway
metadata:
  name: ingress-gateway
spec:
  listeners:
    - port: 8080
      protocol: http
      services:
        - name: frontend
EOF

$ cat > ingress-gateway.yaml << EOF
apiVersion: consul.hashicorp.com/v1alpha1
kind: IngressGateway
metadata:
  name: ingress-gateway
spec:
  listeners:
    - port: 8080
      protocol: http
      services:
        - name: frontend
EOF

Now, register the config entry with Consul.

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

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

»Create the necessary intentions

Since HCP Consul on AWS is secure by default, the datacenter is created with a "default deny" intention in place. This means that, by default, no services can interact with each other until an operator explicitly allows them to do so by creating intentions for each inter-service operation they wish to allow.

As of Consul 1.9, service-intentions config entries can be created using CRDs. Use the following command to create a file named service-intentions.yaml.

$ cat > service-intentions.yaml << EOF
apiVersion: consul.hashicorp.com/v1alpha1
kind: ServiceIntentions
metadata:
  name: ingress-gateway-to-frontend
spec:
  destination:
    name: frontend
  sources:
    - name: ingress-gateway
      action: allow
---
apiVersion: consul.hashicorp.com/v1alpha1
kind: ServiceIntentions
metadata:
  name: frontend-to-public-api
spec:
  destination:
    name: public-api
  sources:
    - name: frontend
      action: allow
---
apiVersion: consul.hashicorp.com/v1alpha1
kind: ServiceIntentions
metadata:
  name: public-api-to-product-api
spec:
  destination:
    name: product-api
  sources:
    - name: public-api
      action: allow
---
apiVersion: consul.hashicorp.com/v1alpha1
kind: ServiceIntentions
metadata:
  name: product-api-to-postgres
spec:
  destination:
    name: postgres
  sources:
    - name: product-api
      action: allow
EOF

$ cat > service-intentions.yaml << EOF
apiVersion: consul.hashicorp.com/v1alpha1
kind: ServiceIntentions
metadata:
  name: ingress-gateway-to-frontend
spec:
  destination:
    name: frontend
  sources:
    - name: ingress-gateway
      action: allow
---
apiVersion: consul.hashicorp.com/v1alpha1
kind: ServiceIntentions
metadata:
  name: frontend-to-public-api
spec:
  destination:
    name: public-api
  sources:
    - name: frontend
      action: allow
---
apiVersion: consul.hashicorp.com/v1alpha1
kind: ServiceIntentions
metadata:
  name: public-api-to-product-api
spec:
  destination:
    name: product-api
  sources:
    - name: public-api
      action: allow
---
apiVersion: consul.hashicorp.com/v1alpha1
kind: ServiceIntentions
metadata:
  name: product-api-to-postgres
spec:
  destination:
    name: postgres
  sources:
    - name: product-api
      action: allow
EOF

Run the following command to create the service-intentions config entries the HashiCups application requires to run.

$ kubectl apply -f ./service-intentions.yaml
serviceintentions.consul.hashicorp.com/ingress-gateway-to-frontend created
serviceintentions.consul.hashicorp.com/frontend-to-public-api created
serviceintentions.consul.hashicorp.com/public-api-to-product-api created
serviceintentions.consul.hashicorp.com/product-api-to-postgres created

$ kubectl apply -f ./service-intentions.yaml
serviceintentions.consul.hashicorp.com/ingress-gateway-to-frontend created
serviceintentions.consul.hashicorp.com/frontend-to-public-api created
serviceintentions.consul.hashicorp.com/public-api-to-product-api created
serviceintentions.consul.hashicorp.com/product-api-to-postgres created

»Access the HashiCups UI

With the intentions in place, all that remains is to retrieve the public URL and port of the ingress gateway. Do this by retrieving a list of services.

$ kubectl get svc --namespace consul
NAME                        TYPE           CLUSTER-IP       EXTERNAL-IP                                                               PORT(S)                         AGE
consul-ingress-gateway      LoadBalancer   172.20.81.249    a7b5d9e6f022548259fa0d616ca8aaf1-1451754202.us-east-1.elb.amazonaws.com   8080:32166/TCP,8443:31069/TCP   8m54s
...TRUNCATED

$ kubectl get svc --namespace consul
NAME                        TYPE           CLUSTER-IP       EXTERNAL-IP                                                               PORT(S)                         AGE
consul-ingress-gateway      LoadBalancer   172.20.81.249    a7b5d9e6f022548259fa0d616ca8aaf1-1451754202.us-east-1.elb.amazonaws.com   8080:32166/TCP,8443:31069/TCP   8m54s
...TRUNCATED

Use the following command to verify you have successfully deployed the application.

$ INGRESS_GATEWAY=$(kubectl get svc/consul-ingress-gateway --namespace consul -o json | jq -r '.status.loadBalancer.ingress[0].hostname') && \
    echo "Connecting to \"$INGRESS_GATEWAY\"" && \
    curl -H "Host: frontend.ingress.consul" "http://$INGRESS_GATEWAY:8080"

$ INGRESS_GATEWAY=$(kubectl get svc/consul-ingress-gateway --namespace consul -o json | jq -r '.status.loadBalancer.ingress[0].hostname') && \
    echo "Connecting to \"$INGRESS_GATEWAY\"" && \
    curl -H "Host: frontend.ingress.consul" "http://$INGRESS_GATEWAY:8080"

Example output:

Connecting to "a32115aa6b19546e188afc44fbb8f3b3-1889150178.us-west-2.elb.amazonaws.com"
&lt;!doctype html&gt;
...TRUNCATED...
&lt;/html&gt;

Connecting to "a32115aa6b19546e188afc44fbb8f3b3-1889150178.us-west-2.elb.amazonaws.com"
&lt;!doctype html&gt;
...TRUNCATED...
&lt;/html&gt;

This validates that Consul service discovery is working, because the services are able to resolve the upstreams. This also validates that Consul service mesh is working, because the intentions that were created are allowing services to interact with one another.

»Next steps

In this tutorial, you connected Consul clients on EKS to HCP Consul and deployed a demo application. To keep learning about Consul's features, and for step-by-step examples of how to perform common Consul tasks, complete one of the following tutorials.

If you encounter any issues, please contact the HCP team at support.hashicorp.com.

Infrastructure

Security

Applications

Networking

cloud

»Prerequisites

»Configure development host

»Configure Consul secrets

»Install Consul on EKS

»Deploy Consul

»Deploy an example workload

»Register a Consul ingress gateway

»Create the necessary intentions

»Access the HashiCups UI

»Next steps