Kubes DSL

Kubes supports a DSL that builds Kubernetes YAML files. The DSL substantially reduces the amount of code you have to write. Each part of the structure can be customized and overridden.

DSL Methods

In general, the available DSL methods correspond to resource fields available. To find available methods:

  1. Look the at the source for each of the resources.
  2. Refer to each resource’s docs, linked at the bottom of this page.
  3. And use the kubectl explain command.

Sometimes the methods may not exactly match to avoid field names collisions. Though this is the exception, not the rule.

Example

Here’s a simple example:

.kubes/resources/web/service.rb

name "demo-web"
labels(role: "web")
namespace "demo"

port 80
targetPort 80

Results in:

.kubes/output/web/service.yaml

---
apiVersion: v1
kind: Service
metadata:
  name: demo-web
  labels:
    app: demo
  namespace: demo
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 8080
  selector:
    app: demo
  type: NodePort

Notice how port and targetPort correspond to spec.ports.port and spec.ports.targetPort in the YAML.

Reader and Writer Methods

In general:

  • The DSL methods behave as reader methods when no arguments are passed to it. IE: name "demo-web" sets the value.
  • The DSL methods behave as writer methods when arguments are passed to it. IE: name returns the value.

Merge Behavior

Generally, the merge should behave as expected. For example, map or Hash fields are merged together from multiple layers. Strings are simply replaced. See more details at Layering Merge Behavior