How to generate yaml template with kubectl command?

There's the command create in kubectl that does the trick and replaced the run used in the past: let's image you want to create a Deployment running a nginx:latest Docker image.

# kubectl create deployment my_deployment --image=busybox --dry-run=client --output=yamlapiVersion: apps/v1kind: Deploymentmetadata:  creationTimestamp: null  labels:    app: my_deployment  name: my_deploymentspec:  replicas: 1  selector:    matchLabels:      app: my_deployment  strategy: {}  template:    metadata:      creationTimestamp: null      labels:        app: my_deployment    spec:      containers:      - image: busybox        name: busybox        resources: {}status: {}

Let's analyze each parameter:

• my_deployment is the Deployment name you chose
• --image is the Docker image you want to deploy
• --dry-run=client won't execute the resource creation, used mainly for validation. Replace 'client' with 'true' for older versions of Kubernetes.
• --output=yaml prints to standard output the YAML definition of the Deployment resource.

Obviously, you can perform this options just with few Kubernetes default resources:

# kubectl create   clusterrole         Create a ClusterRole.  clusterrolebinding  Create a ClusterRoleBinding for a particular ClusterRole  configmap           Create a configmap from a local file, directory or literal value  deployment          Create a deployment with the specified name.  job                 Create a job with the specified name.  namespace           Create a namespace with the specified name  poddisruptionbudget Create a pod disruption budget with the specified name.  priorityclass       Create a priorityclass with the specified name.  quota               Create a quota with the specified name.  role                Create a role with single rule.  rolebinding         Create a RoleBinding for a particular Role or ClusterRole  secret              Create a secret using specified subcommand  service             Create a service using specified subcommand.  serviceaccount      Create a service account with the specified name

According to this, you can render the template without the prior need of deploying your resource.

Also kubectl explain can be used for different resources. It will not generate an yaml file for a standard pod, but it will display a description for one, e.g.:

kubectl explain pods

for getting details for a section/property in the pod:

kubectl explain pods.spec

One can also output the resulting explanation to an yaml file and edit that:

kubectl explain pods > mypod.yaml

AND!with

kubectl explain pod --recursive

one gets the whole structure of a resource without the explaining; exporting to a yaml file can represent an empty skeleton for the intended resource; below a segment for the pod:

KIND:     PodVERSION:  v1DESCRIPTION:     Pod is a collection of containers that can run on a host. This resource is     created by clients and scheduled onto hosts.FIELDS:   apiVersion   <string>   kind <string>   metadata <Object>      annotations   <map[string]string>      clusterName   <string>      creationTimestamp <string>      deletionGracePeriodSeconds    <integer>      deletionTimestamp <string>      finalizers    <[]string>      generateName  <string>      generation    <integer>      labels    <map[string]string>      managedFields <[]Object>         apiVersion <string>         fieldsType <string>         fieldsV1   <map[string]>         manager    <string>         operation  <string>         time   <string>      name  <string>      namespace <string>      ownerReferences   <[]Object>         apiVersion <string>         blockOwnerDeletion <boolean>         controller <boolean>         kind   <string>         name   <string>         uid    <string>      resourceVersion   <string>      selfLink  <string>      uid   <string>   spec <Object>      activeDeadlineSeconds <integer>      affinity  <Object>         nodeAffinity   <Object>            preferredDuringSchedulingIgnoredDuringExecution <[]Object>               preference   <Object>                  matchExpressions  <[]Object>                     key    <string>                     operator   <string>                     values <[]string>                  matchFields   <[]Object>                     key    <string>                     operator   <string>                     values <[]string>               weight   <integer>            requiredDuringSchedulingIgnoredDuringExecution  <Object>               nodeSelectorTerms    <[]Object>                  matchExpressions  <[]Object>                     key    <string>                     operator   <string>                     values <[]string>                  matchFields   <[]Object>                     key    <string>                     operator   <string>                     values <[]string>         podAffinity    <Object>            preferredDuringSchedulingIgnoredDuringExecution <[]Object>               podAffinityTerm  <Object>                  labelSelector <Object>                     matchExpressions   <[]Object>                        key <string>                        operator    <string>                        values  <[]string>                     matchLabels    <map[string]string>                  namespaces    <[]string>                  topologyKey   <string>               weight   <integer>            requiredDuringSchedulingIgnoredDuringExecution  <[]Object>               labelSelector    <Object>                  matchExpressions  <[]Object>                     key    <string>                     operator   <string>                     values <[]string>                  matchLabels   <map[string]string>               namespaces   <[]string>               topologyKey  <string>         podAntiAffinity    <Object>            preferredDuringSchedulingIgnoredDuringExecution <[]Object>               podAffinityTerm  <Object>                  labelSelector <Object>                     matchExpressions   <[]Object>                        key <string>                        operator    <string>                        values  <[]string>                        .                        .                        .