I saw that there is an object named PodTemplate which have little documentation.

It is mentioned:

Pod templates are pod specifications which are included in other objects, such as Replication Controllers, Jobs, and DaemonSets.

But I am not sure how to mention it on Replication Controllers, Jobs or DaemonSets.

I created a PodTemplate like this:

kubectl apply -f - <<EOF
apiVersion: v1
kind: PodTemplate
metadata:
  name: pod-test
  namespace: default
template:
  metadata:
    name: pod-template
  spec:
    containers:
    - name: container
      image: alpine
      command: ["/bin/sh"]
      args: ["-c", "sleep 100"]
EOF

I want to use it in a DaemonSet, how can I do it ?

Here is an example for DaemonSet YAML:

kubectl apply -f - <<EOF
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: pod-by-daemonset
  namespace: default
spec:
  selector:
    matchLabels:
      name: selector
  template:
    metadata:
      labels:
        name: selector
    spec:
      containers: # I don't want to specify it, I want to use the template.
      - name: container
        image: alpine 

EOF