<p>I am trying to do the prerequisites mentioned in <a href="https://hub.helm.sh/charts/jetstack/cert-manager" rel="nofollow noreferrer">https://hub.helm.sh/charts/jetstack/cert-manager</a></p>

<pre><code>$ kubectl apply \
    -f https://raw.githubusercontent.com/jetstack/cert-manager/release-0.11/deploy/manifests/00-
</code></pre>

<p>I tried to figure out what <code>kubectl apply</code> does since I joined a project with k8s already up and running and therefore having not much basic knowledge.</p>

<p><a href="https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#apply" rel="nofollow noreferrer">https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#apply</a></p>

<p>The guide says:</p>

<p>Apply the configuration in <code>pod.json</code> to a pod.</p>

<p><code>kubectl apply -f ./pod.json</code></p>

<p>But I don't get why in this command no target is mentioned. I expected something like:</p>

<p><code>kubectl apply -f ./pod.json application-pod-01</code> </p>

<p>But nowhere is an explicit target for this <code>apply</code> command of the file mentioned. I am sure I am missing a crucial concept here but can't figure it out by reading up the doc.</p>

xetra11
<p>Most objects in the kubernetes API have a namespace and a name (if namespace is left out of the definition it defaults to the <code>default</code> namespace), defined in the <a href="https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.16/#objectmeta-v1-meta" rel="nofollow noreferrer">ObjectMetaData</a>. </p>

<p>In the yaml file you will see the following:</p>

<pre><code>apiVersion: v1
kind: Pod
metadata:
  name: application-pod
  namespace: my-namespace
</code></pre>

<p>The combination of name and namespace uniquily identify the object in Kubernetes, and allow kubernetes to find a specific instance  of the object (e.g. <code>pod-01</code>) and update it (most likely creating a new instance of the object, e.g. <code>pod-02</code>).</p>
