7 Mounting storage volumes into the Pod’s containers

The previous two chapters focused on the pod’s containers, but they are only half of what a pod typically contains. They are typically accompanied by storage volumes that allow a pod’s containers to store data for the lifetime of the pod or beyond, or to share files with the other containers of the pod. This is the focus of this chapter.

7.1      Introducing volumes

A pod is like a small logical computer that runs a single application. This application can consist of one or more containers that run the application processes. These processes share computing resources such as CPU, RAM, network interfaces, and others. In a typical computer, the processes use the same filesystem, but this isn’t the case with containers. Instead, each container has its own isolated filesystem provided by the container image.

7.1.1   Understanding how volumes fit into pods

7.1.2   Introducing volume types

7.2      Using volumes

7.2.1   Using an emptyDir volume to persist files across container restarts

7.2.2   Using an emptyDir volume to share files between containers

7.2.3   Specifying how a volume is to be mounted in the container

7.3      Integrating external storage into pods

7.3.1   Using a Google Compute Engine Persistent Disk in a pod volume

7.3.2   Using other persistent volume types

7.3.3   Understanding how external volumes are mounted

7.4      Accessing files on the worker node’s filesystem

7.4.1   Introducing the hostPath volume

7.4.2   Using a hostPath volume

7.5      Summary