Automated Operations

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Other tutorials in this section feature the ways that CockroachDB automates operations for you. On top of this built-in automation, you can use a third-party orchestration system to simplify and automate even more of your operations, from deployment to scaling to overall cluster management.

This page walks you through a simple demonstration, using the open-source Kubernetes orchestration system. Starting with a few configuration files, you'll quickly create an insecure 3-node local cluster. You'll run a load generator against the cluster and then simulate node failure, watching how Kubernetes auto-restarts without the need for any manual intervention. You'll then scale the cluster with a single command before shutting the cluster down, again with a single command.

Note:

To orchestrate a physically distributed cluster in production, see Orchestrated Deployment.

Before You Begin

Before getting started, it's helpful to review some Kubernetes-specific terminology:

Feature	Description
minikube	This is the tool you'll use to run a Kubernetes cluster inside a VM on your local workstation.
pod	A pod is a group of one or more Docker containers. In this tutorial, all pods will run on your local workstation, each containing one Docker container running a single CockroachDB node. You'll start with 3 pods and grow to 4.
StatefulSet	A StatefulSet is a group of pods treated as stateful units, where each pod has distinguishable network identity and always binds back to the same persistent storage on restart. StatefulSets are considered stable as of Kubernetes version 1.9 after reaching beta in version 1.5.
persistent volume	A persistent volume is a piece of local storage mounted into a pod. The lifetime of a persistent volume is decoupled from the lifetime of the pod that's using it, ensuring that each CockroachDB node binds back to the same storage on restart. When using `minikube`, persistent volumes are external temporary directories that endure until they are manually deleted or until the entire Kubernetes cluster is deleted.
persistent volume claim	When pods are created (one per CockroachDB node), each pod will request a persistent volume claim to “claim” durable storage for its node.

Step 1. Start Kubernetes

Follow Kubernetes' documentation to install minikube, the tool used to run Kubernetes locally, for your OS. This includes installing a hypervisor and kubectl, the command-line tool used to managed Kubernetes from your local workstation.

Note:
Make sure you install minikube version 0.21.0 or later. Earlier versions do not include a Kubernetes server that supports the maxUnavailability field and PodDisruptionBudget resource type used in the CockroachDB StatefulSet configuration.
Start a local Kubernetes cluster:
```
$ minikube start
```

Step 2. Start CockroachDB nodes

When starting a cluster manually, you run the cockroach start command multiple times, once per node. In this step, you use a Kubernetes StatefulSet configuration instead, reducing the effort of starting 3 nodes to a single command.

From your local workstation, use our cockroachdb-statefulset.yaml file to create the StatefulSet that automatically creates 3 pods, each with a CockroachDB node running inside it:

$ kubectl create -f https://raw.githubusercontent.com/cockroachdb/cockroach/master/cloud/kubernetes/cockroachdb-statefulset.yaml

service "cockroachdb-public" created
service "cockroachdb" created
poddisruptionbudget "cockroachdb-budget" created
statefulset "cockroachdb" created

Confirm that three pods are Running successfully. Note that they will not be considered Ready until after the cluster has been initialized:

$ kubectl get pods

NAME            READY     STATUS    RESTARTS   AGE
cockroachdb-0   0/1       Running   0          2m
cockroachdb-1   0/1       Running   0          2m
cockroachdb-2   0/1       Running   0          2m

Confirm that the persistent volumes and corresponding claims were created successfully for all three pods:

$ kubectl get persistentvolumes

NAME                                       CAPACITY   ACCESSMODES   RECLAIMPOLICY   STATUS    CLAIM                           REASON    AGE
pvc-52f51ecf-8bd5-11e6-a4f4-42010a800002   1Gi        RWO           Delete          Bound     default/datadir-cockroachdb-0             26s
pvc-52fd3a39-8bd5-11e6-a4f4-42010a800002   1Gi        RWO           Delete          Bound     default/datadir-cockroachdb-1             27s
pvc-5315efda-8bd5-11e6-a4f4-42010a800002   1Gi        RWO           Delete          Bound     default/datadir-cockroachdb-2             27s

Step 3. Initialize the cluster

Use our cluster-init.yaml file to perform a one-time initialization that joins the nodes into a single cluster:
```
$ kubectl create -f https://raw.githubusercontent.com/cockroachdb/cockroach/master/cloud/kubernetes/cluster-init.yaml
```
```
job "cluster-init" created
```

Confirm that cluster initialization has completed successfully. The job should be considered successful and the CockroachDB pods should soon be considered Ready:

$ kubectl get job cluster-init

NAME           DESIRED   SUCCESSFUL   AGE
cluster-init   1         1            2m

$ kubectl get pods

NAME            READY     STATUS    RESTARTS   AGE
cockroachdb-0   1/1       Running   0          3m
cockroachdb-1   1/1       Running   0          3m
cockroachdb-2   1/1       Running   0          3m

Tip:

The StatefulSet configuration sets all CockroachDB nodes to log to stderr, so if you ever need access to a pod/node's logs to troubleshoot, use kubectl logs <podname> rather than checking the log on the persistent volume.

Step 4. Test the cluster

To test the cluster, launch a temporary pod for using the built-in SQL client, and then use a deployment configuration file to run a high-traffic load generator against the cluster from another pod.

Launch a temporary interactive pod and start the built-in SQL client inside it:

$ kubectl run cockroachdb -it --image=cockroachdb/cockroach --rm --restart=Never \
-- sql --insecure --host=cockroachdb-public

Run some basic CockroachDB SQL statements:

> CREATE DATABASE bank;

> CREATE TABLE bank.accounts (id INT PRIMARY KEY, balance DECIMAL);

> INSERT INTO bank.accounts VALUES (1, 1000.50);

> SELECT * FROM bank.accounts;

+----+---------+
| id | balance |
+----+---------+
|  1 |  1000.5 |
+----+---------+
(1 row)

Exit the SQL shell and delete the temporary pod:
```
> \q
```
Use our example-app.yaml file to launch a pod and run a load generator against the cluster from the pod:
```
$ kubectl create -f https://raw.githubusercontent.com/cockroachdb/cockroach/master/cloud/kubernetes/example-app.yaml
```
```
deployment "example" created
```

Verify that the pod for the load generator was added successfully:

$ kubectl get pods

NAME                      READY     STATUS    RESTARTS   AGE
cockroachdb-0             1/1       Running   0          28m
cockroachdb-1             1/1       Running   0          27m
cockroachdb-2             1/1       Running   0          10m
example-545f866f5-2gsrs   1/1       Running   0          25m

Step 5. Monitor the cluster

To access the Admin UI and monitor the cluster's state and the load generator's activity:

Port-forward from your local machine to one of the pods:
```
$ kubectl port-forward cockroachdb-0 8080
```
```
Forwarding from 127.0.0.1:8080 -> 8080
```
Go to http://localhost:8080.
On the Cluster Overview, note that there are 3 healthy nodes with many SQL inserts executing per second across them.
Click the Databases tab on the left to verify that the bank database you created manually, as well as the kv database created by the load generated, are listed.

Step 6. Simulate node failure

Based on the replicas: 3 line in the StatefulSet configuration, Kubernetes ensures that three pods/nodes are running at all times. When a pod/node fails, Kubernetes automatically creates another pod/node with the same network identity and persistent storage.

To see this in action:

Terminate one of the CockroachDB nodes:
```
$ kubectl delete pod cockroachdb-2
```
```
pod "cockroachdb-2" deleted
```
In the Admin UI, the Summary panel will soon show one node as Suspect. As Kubernetes auto-restarts the node, watch how the node once again becomes healthy.

Back in the terminal, verify that the pod was automatically restarted:

$ kubectl get pod cockroachdb-2

NAME            READY     STATUS    RESTARTS   AGE
cockroachdb-2   1/1       Running   0          12s

Step 7. Scale the cluster

Use the kubectl scale command to add a pod for another CockroachDB node:
```
$ kubectl scale statefulset cockroachdb --replicas=4
```
```
statefulset "cockroachdb" scaled
```

Verify that the pod for a fourth node, cockroachdb-3, was added successfully:

$ kubectl get pods

NAME                      READY     STATUS    RESTARTS   AGE
cockroachdb-0             1/1       Running   0          28m
cockroachdb-1             1/1       Running   0          27m
cockroachdb-2             1/1       Running   0          10m
cockroachdb-3             1/1       Running   0          5s
example-545f866f5-2gsrs   1/1       Running   0          25m

Step 8. Stop the cluster

If you plan to restart the cluster, use the minikube stop command. This shuts down the minikube virtual machine but preserves all the resources you created:
```
$ minikube stop
```
```
Stopping local Kubernetes cluster...
Machine stopped.
```
You can restore the cluster to its previous state with minikube start.
If you do not plan to restart the cluster, use the minikube delete command. This shuts down and deletes the minikube virtual machine and all the resources you created, including persistent volumes:
```
$ minikube delete
```
```
Deleting local Kubernetes cluster...
Machine deleted.
```
Tip:
To retain logs, copy them from each pod's stderr before deleting the cluster and all its resources. To access a pod's standard error stream, run kubectl logs <podname>.

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