Generate dynamic config

The real power of Overboard is not only the awesome declarative builder syntax enabled by F# but also that we can leverage the full power of a programming language instead of some hacky templating language.

In the example below we define a function that defines a deployment and a service based on the application name and port number passed to the function.

The function nomalizes the name by lowercasing it and stripping any special characters from it. This is a great way to standardize on naming conventions without always requiring that everyone always remembers the standards.

open System
open Overboard
open Overboard.Common
open Overboard.Workload
open Overboard.Service

/// Returns a deployment and service for `appName`
let publicApi appName portNumber =
    /// Lowercase the name and allow only letters and digits
    let normalize (name: string) =
        name.ToLowerInvariant().ToCharArray() 
        |> Array.filter Char.IsLetterOrDigit
        |> String
    let normalizedName = normalize appName
    let matchOn = ("app", normalizedName)
    k8s {
        deployment {
            $"{normalizedName}-deploy"
            _labels [matchOn]
            replicas 2
            add_matchLabel ("app", normalizedName)
            pod {
                $"{normalizedName}-pod"
                _labels [matchOn]
                container {
                    "nginx"
                    image "nginx"
                }
            }
        }
        service {
            $"{normalizedName}-service"
            _labels [matchOn]
            typeOf ServiceType.NodePort
            matchLabel matchOn
            servicePort {
                port portNumber
                protocol Protocol.TCP
            }
        }
    }

// Use the `publicApi` function to create 2 lists or resources and combine them into a new `K8s` instance. 
let k8sConfig = k8s {
    publicApi "Checkout" 80
    publicApi "Payments" 81
 }

// Get the output content and validation errors
let k8sOutput = KubeCtlWriter.toYaml k8sConfig

Output

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: checkout
  name: checkout-deploy
  namespace: default
spec:
  minReadySeconds: 0
  progressDeadlineSeconds: 600
  replicas: 2
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: checkout
  template:
    metadata:
      labels:
        app: checkout
      name: checkout-pod
      namespace: default
    spec:
      containers:
      - image: nginx
        name: nginx
        resources:
          limits:
            cpu: 1000m
            memory: 512Mi
          requests:
            cpu: 500m
            memory: 256Mi
      restartPolicy: Always

---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: checkout
  name: checkout-service
  namespace: default
spec:
  ports:
  - port: 80
    protocol: TCP
  selector:
    app: checkout
  type: NodePort

---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: payments
  name: payments-deploy
  namespace: default
spec:
  minReadySeconds: 0
  progressDeadlineSeconds: 600
  replicas: 2
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: payments
  template:
    metadata:
      labels:
        app: payments
      name: payments-pod
      namespace: default
    spec:
      containers:
      - image: nginx
        name: nginx
        resources:
          limits:
            cpu: 1000m
            memory: 512Mi
          requests:
            cpu: 500m
            memory: 256Mi
      restartPolicy: Always

---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: payments
  name: payments-service
  namespace: default
spec:
  ports:
  - port: 81
    protocol: TCP
  selector:
    app: payments
  type: NodePort