Eval

Alpha Feature

Eval is very similar to show but it differs in a fundamental way, it does not traverse the code in search of kubernetes manifests, it instead behaves more like jsonnet command and does just evaluate the jsonnet code to output

This is useful in order to troubleshoot some jsonnet code that , because of the use of kubecfg native extension, cannot be rendered using standard jsonnet

Jsonnet Code

local kubecfg = import 'kubecfg.libsonnet';

{
  local outer = self,

  container:: {
    name: 'busybox',
    image: 'busybox:latest',
  },

  deployment: {
    local this = self,

    apiVersion: 'extensions/v1beta1',
    kind: 'Deployment',
    metadata: {
      name: 'busybox',
      labels: { name: 'busybox' },
    },
    spec: {
      replicas: 3,
      template: {
        metadata: { labels: this.metadata.labels },
        spec: {
          containers: [outer.container],
        },
      },
    },
  },
}

Basic Rendering

render jsonnet to stdout in YAML format

kubecfg --alpha eval source.jsonnet

➜ kubecfg --alpha eval code.jsonnet
deployment:
  apiVersion: extensions/v1beta1
  kind: Deployment
  metadata:
    labels:
      name: busybox
    name: busybox
  spec:
    replicas: 3
    template:
      metadata:
        labels:
          name: busybox
      spec:
        containers:
        - image: busybox:latest
          name: busybox

render to stdout in JSON format

kubecfg --alpha eval -o json source.jsonnet

{
   "deployment": {
      "apiVersion": "extensions/v1beta1",
      "kind": "Deployment",
      "metadata": {
         "labels": {
            "name": "busybox"
         },
         "name": "busybox"
      },
      "spec": {
         "replicas": 3,
         "template": {
            "metadata": {
               "labels": {
                  "name": "busybox"
               }
            },
            "spec": {
               "containers": [
                  {
                     "image": "busybox:latest",
                     "name": "busybox"
                  }
               ]
            }
         }
      }
   }
}