Add Kubernetes YAML with CRD example (#477)

Author: polkx

examples/kubernetes-yaml-crd/.gitignore

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+### Scala an JVM
+*.class
+*.log
+.bsp
+.scala-build
+
+# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
+hs_err_pid*

examples/kubernetes-yaml-crd/Main.scala

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+import besom.*
+import besom.api.kubernetes as k8s
+
+@main def main = Pulumi.run {
+
+  val crd =
+    k8s.yaml.v2.ConfigGroup(
+      name = "config-group",
+      k8s.yaml.v2.ConfigGroupArgs(
+        yaml = """apiVersion: apiextensions.k8s.io/v1
+          |kind: CustomResourceDefinition
+          |metadata:
+          |  # name must match the spec fields below, and be in the form: <plural>.<group>
+          |  name: crontabs.stable.example.com
+          |spec:
+          |  # group name to use for REST API: /apis/<group>/<version>
+          |  group: stable.example.com
+          |  # list of versions supported by this CustomResourceDefinition
+          |  versions:
+          |    - name: v1
+          |      # Each version can be enabled/disabled by Served flag.
+          |      served: true
+          |      # One and only one version must be marked as the storage version.
+          |      storage: true
+          |      schema:
+          |        openAPIV3Schema:
+          |          type: object
+          |          properties:
+          |            spec:
+          |              type: object
+          |              properties:
+          |                cronSpec:
+          |                  type: string
+          |                image:
+          |                  type: string
+          |                replicas:
+          |                  type: integer
+          |  # either Namespaced or Cluster
+          |  scope: Namespaced
+          |  names:
+          |    # plural name to be used in the URL: /apis/<group>/<version>/<plural>
+          |    plural: crontabs
+          |    # singular name to be used as an alias on the CLI and for display
+          |    singular: crontab
+          |    # kind is normally the CamelCased singular type. Your resource manifests use this.
+          |    kind: CronTab
+          |    # shortNames allow shorter string to match your resource on the CLI
+          |    shortNames:
+          |    - ct
+          |    """.stripMargin
+      )
+    )
+
+  val cronTab =
+    k8s.yaml.v2.ConfigGroup(
+      name = "cron-tab",
+      k8s.yaml.v2.ConfigGroupArgs(
+        yaml = """apiVersion: "stable.example.com/v1"
+            |kind: CronTab
+            |metadata:
+            |  name: my-new-cron-object
+            |spec:
+            |  cronSpec: "* * * * */5"
+            |  image: my-awesome-cron-image
+            |  """.stripMargin
+      ),
+      opts = opts(dependsOn = crd)
+    )
+
+  Stack.exports(
+    crdResource = crd.resources,
+    cronTabResource = cronTab.resources
+  )
+}

examples/kubernetes-yaml-crd/Pulumi.yaml

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+name: kubernetes-yaml-crd
+runtime: scala
+description: Example of a Kubernetes Application using plain YAML files with custom CRD

examples/kubernetes-yaml-crd/README.md

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+# Kubernetes application using plain YAML files with custom CRD
+
+Example based
+on [Kubernetes custom resource definitions](https://kubernetes.io/docs/tasks/extend-kubernetes/custom-resources/custom-resource-definitions/).
+Uses plain YAML files to create custom CronTab CRD and deploy it to Kubernetes cluster.
+
+## Prerequisites
+
+Follow the steps in [Pulumi Installation and
+Setup](https://www.pulumi.com/docs/get-started/install/) and [Configuring Pulumi
+Kubernetes](https://www.pulumi.com/docs/intro/cloud-providers/kubernetes/setup/) to get set up with
+Pulumi and Kubernetes.
+
+## Running the App
+
+1. Create a new stack:
+
+   ```sh
+   $ pulumi stack init
+   Enter a stack name: dev
+   ```
+
+2. Preview the deployment of the application and perform the deployment:
+
+   ```sh
+   $ pulumi up
+   ```
+
+3. You can then manage your CronTab objects using kubectl:
+
+   ```sh
+   $ kubectl get crontab
+   ```
+   Should print a list like this:
+   ```
+   NAME                 AGE
+   my-new-cron-object   6s
+   ```
+
+4. You can also view the raw YAML data:
+
+   ```sh
+   $ kubectl get ct -o yaml
+   ```
+
+5. From there, feel free to experiment. Simply making edits and running pulumi up will incrementally update your
+   infrastructure.
+
+6. Once you've finished experimenting, tear down your stack's resources by destroying and removing it:
+
+    ```bash
+    $ pulumi destroy --yes
+    $ pulumi stack rm --yes
+    ```

examples/kubernetes-yaml-crd/project.scala

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+//> using scala "3.3.1"
+//> using options -Werror -Wunused:all -Wvalue-discard -Wnonunit-statement
+//> using dep "org.virtuslab::besom-core:0.3.1"
+//> using dep "org.virtuslab::besom-kubernetes:4.11.0-core.0.3"