Merge pull request #26952 from tmoschou/update-apt-repo-setup-install-steps

Update Ubuntu/Debian installation instructions to use Signed-By option

content/en/docs/setup/production-environment/tools/kubeadm/install-kubeadm.md

@@ -175,16 +175,34 @@ For more information on version skews, see:
 
 {{< tabs name="k8s_install" >}}
 {{% tab name="Debian-based distributions" %}}
-```bash
-sudo apt-get update && sudo apt-get install -y apt-transport-https curl
-curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
-cat <<EOF | sudo tee /etc/apt/sources.list.d/kubernetes.list
-deb https://apt.kubernetes.io/ kubernetes-xenial main
-EOF
-sudo apt-get update
-sudo apt-get install -y kubelet kubeadm kubectl
-sudo apt-mark hold kubelet kubeadm kubectl
-```
+
+1. Update the `apt` package index and install packages needed to use the Kubernetes `apt` repository:
+
+   ```shell
+   sudo apt-get update
+   sudo apt-get install -y apt-transport-https ca-certificates curl
+   ```
+
+2. Download the Google Cloud public signing key:
+
+   ```shell
+   sudo curl -fsSLo /usr/share/keyrings/kubernetes-archive-keyring.gpg https://packages.cloud.google.com/apt/doc/apt-key.gpg
+   ```
+
+3. Add the Kubernetes `apt` repository:
+
+   ```shell
+   echo "deb [signed-by=/usr/share/keyrings/kubernetes-archive-keyring.gpg] https://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list
+   ```
+
+4. Update `apt` package index, install kubelet, kubeadm and kubectl, and pin their version:
+
+   ```shell
+   sudo apt-get update
+   sudo apt-get install -y kubelet kubeadm kubectl
+   sudo apt-mark hold kubelet kubeadm kubectl
+   ```
+
 {{% /tab %}}
 {{% tab name="Red Hat-based distributions" %}}
 ```bash