Generating Kubernetes config

Overboard gives a powerful way to define your Kubernetes config but for that to be useful, we need to generate the kubernetes config. Overboard provides some helpers for doing just this in KubeCtlWriter.

let kubeConfig = k8s {
    deployment {
        "my-name" // <- No operation specified
        _labels ["label1", "value1"]
    }
}

Printing to screen

If you would like to see what is generated on your screen you can use the print function.

Note that the print also prints any validation errors.

KubeCtlWriter.print kubeConfig

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    label1: value1
  name: my-name
  namespace: default
spec:
  minReadySeconds: 0
  progressDeadlineSeconds: 600
  replicas: 1
  revisionHistoryLimit: 10
  template: {}

Writing to file

If you would like to save your K8s config to file, you can use either the KubeCtlWriter.toJsonFile or KubeCtlWriter.toYamlFile function. As the names imply, these will save your config as JSON or YAML respectively.

KubeCtlWriter.toYamlFile kubeConfig "deployment.yaml"

Getting the content

You can also get the K8sOutput, which gives you access to not only the JSON or YAML K8sOutput.content, but also to the K8sOutput.errors. This is an array of validation errors that Overboard has found in the schema. Overboard prevents many schema issues by being strongly typed but it also runs validation on values that should not be empty or should follow certain formatting. It will still generate the config you specify but gives you errors that you can check before submitting the config to a Kubernetes cluster.

let k8sOutput = KubeCtlWriter.toYaml kubeConfig
makeYaml k8sOutput.content

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    label1: value1
  name: my-name
  namespace: default
spec:
  minReadySeconds: 0
  progressDeadlineSeconds: 600
  replicas: 1
  revisionHistoryLimit: 10
  template: {}

Validation errors

As mentioned, K8sOutput contains an errors field that contains a list of validation errors.

Each ValidationProblem has a Message field on it that gives back a string. You can print these errors out:

k8sOutput.errors 
|> List.map (fun err -> err.Message)
|> List.iter (eprintfn "%s")