ytt example

_cmd

$ ytt -f rebase.yml -f input.yml -f cluster.yaml

cluster.yaml

type:
  kind: Cluster
  package: vmware.tanzu.manage.v1alpha1.cluster
  version: v1alpha1
fullName:
  managementClusterName: "seti-labs" 
  name: cluster-cli
  provisionerName: "lab"
meta:
  labels: null
spec:
  clusterGroupName: seti-labs
  tkgServiceVsphere:
    distribution:
      version: v1.18.10+vmware.1-tkg.1.3a6cd48
    settings:
      network:
        pods:
          cidrBlocks:
          - 192.0.2.0/16
        services:
          cidrBlocks:
          - 198.51.100.0/12
      storage:
        classes:
        - k8s-storage-policy
        defaultClass: "k8s-storage-policy"
    topology:
      controlPlane:
        class: best-effort-medium
        highAvailability: false
        storageClass: k8s-storage-policy
      nodePools:
      - info:
          description: default description for the nodepool
          name: default-node-pool
        spec:
          tkgServiceVsphere:
            class: best-effort-medium
            storageClass: k8s-storage-policy
          workerNodeCount: "1" 

input.yml

fullName:
  managementClusterName: seti-labs
  name: cluster-cli
  orgId: d8bdaf07-6e61-4310-92f3-8c52e24a2d54
  provisionerName: lab
meta:
  annotations:
    authoritativeRID: rid:c:d8bdaf07-6e61-4310-92f3-8c52e24a2d54:seti-labs:lab:cluster-cli
  creationTime: "2021-07-29T15:58:55.248931Z"
  labels:
    tmc.cloud.vmware.com/creator: warroyo
  parentReferences:
  - rid: rid:cg:d8bdaf07-6e61-4310-92f3-8c52e24a2d54:seti-labs
    uid: cg:01F1NCANC0FMN0SW6XBE4XZZ8H
  - rid: rid:prvn:d8bdaf07-6e61-4310-92f3-8c52e24a2d54:seti-labs:lab
    uid: prvn:01FAG4ZRWPB44MBJKPWAAREYXB
  resourceVersion: 81730:31255308
  uid: c:01FBSFTXRJTG4QE97M4W2SNX2X
  updateTime: "2021-07-29T19:30:43Z"
spec:
  clusterGroupName: seti-labs
  tkgServiceVsphere:
    distribution:
      version: v1.18.10+vmware.1-tkg.1.3a6cd48
    settings:
      network:
        pods:
          cidrBlocks:
          - 192.0.2.0/16
        services:
          cidrBlocks:
          - 198.51.100.0/12
      storage:
        classes:
        - k8s-storage-policy
        defaultClass: k8s-storage-policy
    topology:
      controlPlane:
        class: best-effort-medium
        storageClass: k8s-storage-policy
status:
  allocatedCpu:
    allocatable: 4000
    allocatedPercentage: 79
    requested: 3180
    units: millicores
  allocatedMemory:
    allocatable: 15747
    allocatedPercentage: 19
    requested: 3066
    units: mb
  conditions:
    Agent-READY:
      message: cluster is connected to TMC and healthy
      reason: 'phase: COMPLETE, health: HEALTHY'
      severity: INFO
      status: "TRUE"
      type: READY
    WCM-Ready:
      severity: INFO
      status: "TRUE"
      type: Ready
    WCM-VersionIsLatest:
      message: Version v1.20.7+vmware.1-tkg.1.7fb9067 is available for upgrade
      severity: INFO
      status: "FALSE"
      type: VersionIsLatest
  health: HEALTHY
  healthDetails:
    controllerManagerHealth:
      message: Health status is unsupported for kube server version [v1.18.10+vmware.1].
      name: controller-manager
    etcdHealth:
    - health: HEALTHY
      message: Healthy
      name: etcd-0
    message: Cluster is healthy
    schedulerHealth:
      message: Health status is unsupported for kube server version [v1.18.10+vmware.1].
      name: scheduler
    timestamp: "2021-07-29T19:21:54.366891Z"
  infrastructureProvider: VMWARE_VSPHERE
  kubeServerVersion: v1.18.10+vmware.1
  kubernetesProvider:
    type: VMWARE_TANZU_KUBERNETES_GRID_SERVICE
  nodeCount: "2"
  phase: READY
  type: TANZU_KUBERNETES_GRID_SERVICE
type:
  kind: Cluster
  package: vmware.tanzu.manage.v1alpha1.cluster
  version: v1alpha1

rebase.yml

#@ load("@ytt:overlay", "overlay")
#@ load("@ytt:template", "template")
#@ load("@ytt:data", "data")
#@ load("@ytt:yaml", "yaml")

#! remove current state from the output
#@overlay/match by=lambda i,l,r: "uid" in l["meta"]
#@overlay/remove
---

#! load current state into a variable
#@ current = yaml.decode(data.read("input.yml"))

#! combine desired state with current state
#@overlay/match by=overlay.all
---
fullName:
  #@overlay/match missing_ok=True
  orgId: #@ current["fullName"]["orgId"]

#@yaml/text-templated-strings
meta:
  #@ meta = current["meta"]

  #@overlay/match missing_ok=True
  annotations:
    #@ for/end k in meta["annotations"]:
    #@overlay/match when=0
    (@= k @): #@ meta["annotations"][k]

  #@overlay/match missing_ok=True
  labels:
    #@ for/end k in meta["labels"]:
    #@overlay/match when=0
    (@= k @): #@ meta["labels"][k]

  #@ meta.pop("labels")
  #@ meta.pop("annotations")

  #@ for/end k in meta:
  #@overlay/match missing_ok=True
  (@= k @): #@ meta[k]

#@overlay/match missing_ok=True
status: #@ current["status"]