Run `kubectl apply` using yaml stored in a variable

Question

I have a resource I want to apply as part of an automated script (running in powershell). I would rather not have to write it out to a file then have to deal with cleaning it up.

Is it possible to apply the yaml as part of a script?

Something similar to this:

$myYaml = @'
apiVersion: "rbac.authorization.k8s.io/v1"
kind: RoleBinding
metadata:
  name: ServiceAccount-clusteradmin
roleRef:
  apiGroup: "rbac.authorization.k8s.io"
  kind: ClusterRole
  name: ClusterAdmin
subjects:
  - apiGroup: "rbac.authorization.k8s.io"
    kind: User
    name: "MyAdminServiceAccount"
'@

kubectl apply @myYaml

Clearly, the kubectl command above does not work.

My question is: Is a way to apply this yaml without creating a file (using powershell)?

Answer 1

myYaml is a variable having the data:

$myYaml = @'
apiVersion: "rbac.authorization.k8s.io/v1"
kind: RoleBinding
metadata:
  name: ServiceAccount-clusteradmin
roleRef:
  apiGroup: "rbac.authorization.k8s.io"
  kind: ClusterRole
  name: ClusterAdmin
subjects:
  - apiGroup: "rbac.authorization.k8s.io"
    kind: User
    name: "MyAdminServiceAccount"
'@

Perform the following to echo the contents of $myYaml variable and pipe it to kubectl apply -f -, here last - is for piped input.

$myYaml |kubectl.exe apply -f -
rolebinding.rbac.authorization.k8s.io/ServiceAccount-clusteradmin created

kubectl.exe get rolebindings
NAME                          ROLE                       AGE
ServiceAccount-clusteradmin   ClusterRole/ClusterAdmin   18s

This is very similar to linux environment where echo "$var" |kubectl apply -f - is used to perform same action.