upgrade k8s 1.30 -> 1.31 (#676)

* upgrade k8s 1.30 -> 1.31

* add  conntrack dependency

* add  conntrack dependency

* add  conntrack dependency

* update manifests (#678)

Co-authored-by: Neha Manjunath <nehamanjunath@google.com>

* Add comment regarding conntrack dependency

---------

Co-authored-by: Neha Manjunath <nehamanjunath@google.com>

Author: NehaManjunath

cloudbuild/external.pkr.hcl

@@ -93,9 +93,11 @@ build {
   provisioner "shell" {
     inline = [
       "echo Installing kubectl...",
-      "curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.30/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg",
-      "echo \"deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.30/deb/ /\" | sudo tee /etc/apt/sources.list.d/kubernetes.list",
+      "curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.31/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg",
+      "echo \"deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.31/deb/ /\" | sudo tee /etc/apt/sources.list.d/kubernetes.list",
       "sudo apt-get update",
+      // kube-proxy requires conntrack to route traffic, and kubeadm v1.31+ enforces it in preflight checks
+      "sudo apt-get install conntrack -y",
       "sudo apt-get install kubelet kubeadm kubectl -y",
       "kubectl version --client",
       "echo 'source <(kubectl completion bash)' >> ~/.bashrc",

cloudbuild/internal.pkr.hcl

@@ -101,9 +101,11 @@ build {
   provisioner "shell" {
     inline = [
       "echo Installing kubectl...",
-      "curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.30/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg",
-      "echo \"deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.30/deb/ /\" | sudo tee /etc/apt/sources.list.d/kubernetes.list",
+      "curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.31/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg",
+      "echo \"deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.31/deb/ /\" | sudo tee /etc/apt/sources.list.d/kubernetes.list",
       "sudo apt-get update",
+      // kube-proxy requires conntrack to route traffic, and kubeadm v1.31+ enforces it in preflight checks
+      "sudo apt-get install conntrack -y",
       "sudo apt-get install kubelet kubeadm kubectl -y",
       "kubectl version --client",
       "echo 'source <(kubectl completion bash)' >> ~/.bashrc",