Getting Started with Kubernetes

Deploy Consul with Kubernetes

In this guide you will deploy a Consul datacenter with the official Helm chart. You do not need to update any values in the Helm chart for a basic installation. However, you can create a values file with parameters to allow access to the Consul UI.

To complete this guide successfully, you should have an existing Kubernetes cluster, and locally configured Helm and kubectl. If you do not have an existing Kubernetes cluster you can use the Minikube with Consul guide to get started with Consul on Kubernetes.

Deploy Consul

You can deploy a complete Consul datacenter using the official Helm chart. By default, the chart will install three Consul servers and client on all Kubernetes nodes. You can review the Helm chart values to learn more about the default settings.

Download the Helm Chart

First, you will need to clone the official Helm chart from HashiCorp's Github repo.

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

You do not need to update the Helm chart before deploying Consul, it comes with reasonable defaults. Review the Helm chart documentation to learn more about the chart.

Helm Install Consul

To deploy Consul you will need to be in the same directory as the chart.

$ cd consul-helm

Now, you can deploy Consul using helm install. This will deploy three servers and agents on all Kubernetes nodes. The process should be quick, less than 5 minutes.

$ helm install ./consul-helm

NAME:   mollified-robin LAST DEPLOYED: Mon Feb 25 15:57:18 2019 NAMESPACE: default STATUS: DEPLOYED
NAME                             READY  STATUS             RESTARTS  AGE
mollified-robin-consul-25r6z     0/1    ContainerCreating  0         0s
mollified-robin-consul-4p6hr     0/1    ContainerCreating  0         0s
mollified-robin-consul-n82j6     0/1    ContainerCreating  0         0s
mollified-robin-consul-server-0  0/1    Pending            0         0s
mollified-robin-consul-server-1  0/1    Pending            0         0s
mollified-robin-consul-server-2  0/1    Pending            0         0s

The output above has been reduced for readability. However, you can see that there are three Consul servers and three Consul clients on this three node Kubernetes cluster.

Access Consul UI

To access the UI you will need to update the ui values in the Helm chart. Alternatively, if you do not wish to upgrade your cluster, you can set up port forwarding with kubectl.

Create Values File

First, create a values file that can be passed on the command line when upgrading.

# values.yaml
global:
  datacenter: hashidc1
syncCatalog:
  enabled: true
ui:
  service:
    type: 'LoadBalancer'
server:
  affinity: |
    podAntiAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        - labelSelector:
            matchLabels:
              app: {{ template "consul.name" . }}
              release: "{{ .Release.Name }}"
              component: server
        topologyKey: kubernetes.io/hostname

This file renames your datacenter, enables catalog sync, sets up a load balancer service for the UI, and enables affinity to allow only one Consul pod per Kubernetes node. The catalog sync parameters will allow you to see the Kubernetes services in the Consul UI.

Initiate Rolling Update

Finally, initiate the upgrade with helm upgrade and the -f flag that passes in your new values file. This processes should also be quick, less than a minute.

$ helm upgrade consul -f values.yaml

You can now use kubectl get services to discover the external IP of your Consul UI.

$ kubectl get services
NAME                            TYPE           CLUSTER-IP     EXTERNAL-IP             PORT(S)        AGE
consul                          ExternalName   <none>         consul.service.consul   <none>         11d
kubernetes                      ClusterIP      122.16.14.1    <none>                  443/TCP        137d
mollified-robin-consul-dns      ClusterIP      122.16.14.25   <none>                  53/TCP,53/UDP  13d
mollified-robin-consul-server   ClusterIP      None           <none>                  8500/TCP       13d
mollified-robin-consul-ui       LoadBalancer   122.16.31.395  36.276.67.195           80:32718/TCP   13d

Additionally, you can use kubectl get pods to view the new catalog sync process. The catalog sync process will sync Consul and Kubernetes services bidirectionally by default.

$ kubectl get pods
NAME                                                 READY   STATUS      RESTARTS   AGE
mollified-robin-consul-d8mnp                          1/1     Running     0         15d
mollified-robin-consul-p4m89                          1/1     Running     0         15d
mollified-robin-consul-qclqc                          1/1     Running     0         15d
mollified-robin-consul-server-0                       1/1     Running     0         15d
mollified-robin-consul-server-1                       1/1     Running     0         15d
mollified-robin-consul-server-2                       1/1     Running     0         15d
mollified-robin-consul-sync-catalog-f75cd5846-wjfdk   1/1     Running     0         13d

The service should have consul-ui appended to the deployment name. Note, you do not need to specify a port when accessing the dashboard.

Access Consul

In addition to accessing Consul with the UI, you can manage Consul with the HTTP API or by directly connecting to the pod with kubectl.

Kubectl

To access the pod and data directory you can exec into the pod with kubectl to start a shell session.

$ kubectl exec -it mollified-robin-consul-server-0 /bin/sh

This will allow you to navigate the file system and run Consul CLI commands on the pod. For example you can view the Consul members.

$ consul members
Node                                   Address           Status  Type    Build  Protocol  DC        Segment
mollified-robin-consul-server-0        172.20.2.18:8301  alive   server  1.4.2  2         hashidc1  <all>
mollified-robin-consul-server-1        172.20.0.21:8301  alive   server  1.4.2  2         hashidc1  <all>
mollified-robin-consul-server-2        172.20.1.18:8301  alive   server  1.4.2  2         hashidc1  <all>
gke-tier-2-cluster-default-pool-leri5  172.20.1.17:8301  alive   client  1.4.2  2         hashidc1  <default>
gke-tier-2-cluster-default-pool-gnv4   172.20.2.17:8301  alive   client  1.4.2  2         hashidc1  <default>
gke-tier-2-cluster-default-pool-zrr0   172.20.0.20:8301  alive   client  1.4.2  2         hashidc1  <default>

Consul HTTP API

You can use the Consul HTTP API by communicating to the local agent running on the Kubernetes node. You can read the documentation if you are interested in learning more about using the Consul HTTP API with Kubernetes.

Summary

In this guide, you deployed a Consul datacenter in Kubernetes using the official Helm chart. You also configured access to the Consul UI. To learn more about deploying applications that can use Consul's service discovery and service mesh (Connect), read the example in the Minikube with Consul guide.