What Is Crossplane?

Chapter 3. Building a Control Plane with Crossplane

Now that you’re familiar with the benefits of building a control plane with Crossplane, let’s look at how you can do just that.

We designed Crossplane to help platform engineers build cloud control planes for the product engineers they support. As you saw in Chapter 1, platform engineers curate the control plane’s APIs and capabilities, while product engineers consume them. In this section, I’ll focus on the tasks being done, not roles or titles—after all, we hope Crossplane will be useful to you even if you’re not a platform engineer. For that reason, I’ll refer to platform engineers as control plane curators and product engineers as control plane consumers. Consumers specify the desired state of the data plane by making API calls to the control plane. The control plane’s curators define the types and shapes of these APIs.

The APIs that consumers call are abstractions. When they’re called, Crossplane resolves the specified desired state to a set of operations it must make on concrete data plane primitives. Think back to the thermostat analogy from Chapter 2: there, the temperature dial is the abstraction. When you set the temperature, the thermostat must resolve the desired state you’ve specified to a concrete operation—running the heater.

To build a control plane with Crossplane, a curator would take the following steps:

1. Choose the cloud primitives that will make up the data plane.

2. Define the API abstractions consumers ...