How to describe a list of Kubernetes resources from a file

The usual way to describe a resource with kubectl is to call it by its name and namespace. For example,

$ kubectl get pod gke-metadata-server-qqmt6 -n kube-system
NAME                        READY   STATUS    RESTARTS   AGE
gke-metadata-server-qqmt6   1/1     Running   0          31h

To get two resources, one can simply type both names at once. However for large number of resources, it is more convenient to provide a file containing a list of resources. This is the role of the option -f for describe or get. Unfortunately, the documentation is rather limited:

List a pod identified by type and name specified in “pod.yaml” in JSON output format.

kubectl get -f pod.yaml -o json

I would have appreciated a bit more details: how does this file should look like? And how can we add several resources to the same file? There is nothing complicated, but since I couldn’t find any example on the Internet (it’s probably too obvious!), here is mine:

$ cat pods.yaml
apiVersion: v1
items:
  - apiVersion: v1
    kind: Pod
    metadata:
      name: gke-metadata-server-qqmt6
      namespace: kube-system
  - apiVersion: v1
    kind: Pod
    metadata:
      name: kube-dns-autoscaler-645f7d66cf-t49wb
      namespace: kube-system
kind: List

$ kubectl get -f pods.yaml
NAME                                   READY   STATUS    RESTARTS   AGE
gke-metadata-server-qqmt6              1/1     Running   0          31h
kube-dns-autoscaler-645f7d66cf-t49wb   1/1     Running   0          3d17h

I gave a simple example, but the same technique is useful to automate workflows that manipulate other resources, for example with the Argo Kubernetes resource template.