Kubernetes Cookbook

Chapter 4. Creating and Modifying Fundamental Workloads

In this chapter, we present recipes that show you how to manage fundamental Kubernetes workload types: pods and deployments. We show how to create deployments and pods via CLI commands and from a YAML manifest, and explain how to scale and update a deployment.

4.1 Creating a Deployment Using kubectl run

Problem

You want to quickly launch a long-running application such as a web server.

Solution

Use the kubectl run command, a generator that creates a deployment manifest on the fly. For example, to create a deployment that runs the Ghost microblogging platform do the following:

$ kubectl run ghost --image=ghost:0.9

$ kubectl get deploy/ghost
NAME      DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
ghost     1         1         1            0           16s

Discussion

The kubectl run command can take a number of arguments to configure additional parameters of the deployments. For example, you can do the following:

• Set environment variables with --env

• Define container ports with --port

• Define a command to run using --command

• Automatically create an associated service with --expose

• Define the number of pods using --replicas

Typical usages are as follows. To launch Ghost serving on port 2368 and create a service along with it, enter:

$ kubectl run ghost --image=ghost:0.9 --port=2368 --expose

To launch MySQL with the root password set, enter:

$ kubectl run mysql --image=mysql:5.5 --env=MYSQL_ROOT_PASSWORD=root

To launch a busybox container and execute the command ...