Added logic for custom kube proxy yaml for GKE

cluster/gce/container-linux/configure-helper.sh

@@ -1241,6 +1241,13 @@ function start-kube-addons {
 
   # Set up manifests of other addons.
   if [[ "${KUBE_PROXY_DAEMONSET:-}" == "true" ]]; then
+    if [ -n "${CUSTOM_KUBE_PROXY_YAML:-}" ]; then
+      # Replace with custom GKE kube proxy.
+      cat > "$src_dir/kube-proxy/kube-proxy-ds.yaml" <<EOF
+$(echo "$CUSTOM_KUBE_PROXY_YAML")
+EOF
+      update-prometheus-to-sd-parameters "$src_dir/kube-proxy/kube-proxy-ds.yaml"
+    fi
     prepare-kube-proxy-manifest-variables "$src_dir/kube-proxy/kube-proxy-ds.yaml"
     setup-addon-manifests "addons" "kube-proxy"
   fi

cluster/gce/gci/configure-helper.sh

@@ -1780,6 +1780,13 @@ function start-kube-addons {
 
   # Set up manifests of other addons.
   if [[ "${KUBE_PROXY_DAEMONSET:-}" == "true" ]]; then
+    if [ -n "${CUSTOM_KUBE_PROXY_YAML:-}" ]; then
+      # Replace with custom GKE kube proxy.
+      cat > "$src_dir/kube-proxy/kube-proxy-ds.yaml" <<EOF
+$(echo "$CUSTOM_KUBE_PROXY_YAML")
+EOF
+      update-prometheus-to-sd-parameters "$src_dir/kube-proxy/kube-proxy-ds.yaml"
+    fi
     prepare-kube-proxy-manifest-variables "$src_dir/kube-proxy/kube-proxy-ds.yaml"
     setup-addon-manifests "addons" "kube-proxy"
   fi