Fix kubelet upgrade on Container Linux (#556)

* Properly stop and restart kubelet

On Container Linux, kubelet locks itself, this patch stops kubelet
before downloading the new binaries and then starts it back up once
everything is ready.

Signed-off-by: Daniël Franke <daniel@ams-sec.org>

* Download the binaries before stopping kubelet.

Signed-off-by: Daniël Franke <daniel@ams-sec.org>

pkg/upgrader/upgrade/kubernetes_binaries.go

@@ -60,10 +60,18 @@ curl -L "https://github.com/containernetworking/plugins/releases/download/v{{ .C
 
 RELEASE="v{{ .KUBERNETES_VERSION }}"
 
-sudo mkdir -p /opt/bin
-cd /opt/bin
+
+
+sudo mkdir -p /var/tmp/kube-binaries
+cd /var/tmp/kube-binaries
 sudo curl -L --remote-name-all \
      https://storage.googleapis.com/kubernetes-release/release/${RELEASE}/bin/linux/amd64/{kubeadm,kubelet,kubectl}
+
+
+sudo mkdir -p /opt/bin
+cd /opt/bin
+sudo systemctl stop kubelet
+sudo mv /var/tmp/kube-binaries/{kubeadm,kubelet,kubectl} .
 sudo chmod +x {kubeadm,kubelet,kubectl}
 
 curl -sSL "https://raw.githubusercontent.com/kubernetes/kubernetes/${RELEASE}/build/debs/kubelet.service" | \
@@ -73,7 +81,10 @@ curl -sSL "https://raw.githubusercontent.com/kubernetes/kubernetes/${RELEASE}/bu
 sudo mkdir -p /etc/systemd/system/kubelet.service.d
 curl -sSL "https://raw.githubusercontent.com/kubernetes/kubernetes/${RELEASE}/build/debs/10-kubeadm.conf" | \
      sed "s:/usr/bin:/opt/bin:g" | \
-     sudo tee /etc/systemd/system/kubelet.service.d/10-kubeadm.conf
+	 sudo tee /etc/systemd/system/kubelet.service.d/10-kubeadm.conf
+	 
+sudo systemctl daemon-reload
+sudo systemctl start kubelet
 `
 )