From fd28c0a82a56da127ad8e77d34941b57e9e46065 Mon Sep 17 00:00:00 2001
From: Christian Albrecht <christian.albrecht@mayflower.de>
Date: Fri, 1 Mar 2019 10:23:34 +0100
Subject: [PATCH] nixos/kubernetes: Seed docker images before kubelet service
 start

to speed up startup time because it can be parallelized.
---
 .../services/cluster/kubernetes/kubelet.nix   | 23 ++++++++++++++-----
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/nixos/modules/services/cluster/kubernetes/kubelet.nix b/nixos/modules/services/cluster/kubernetes/kubelet.nix
index b3f3c036564..0b1d2a67565 100644
--- a/nixos/modules/services/cluster/kubernetes/kubelet.nix
+++ b/nixos/modules/services/cluster/kubernetes/kubelet.nix
@@ -257,12 +257,7 @@ in
         before = [ "kubelet.target" ];
         path = with pkgs; [ gitMinimal openssh docker utillinux iproute ethtool thin-provisioning-tools iptables socat ] ++ top.path;
         preStart = ''
-          ${concatMapStrings (img: ''
-            echo "Seeding docker image: ${img}"
-            docker load <${img}
-          '') cfg.seedDockerImages}
-
-          rm /opt/cni/bin/* || true
+          rm -f /opt/cni/bin/* || true
           ${concatMapStrings (package: ''
             echo "Linking cni package: ${package}"
             ln -fs ${package}/bin/* /opt/cni/bin
@@ -328,6 +323,22 @@ in
 
       systemd.services.docker.before = [ "kubelet.service" ];
 
+      systemd.services.docker-seed-images = {
+        wantedBy = [ "docker.service" ];
+        after = [ "docker.service" ];
+        before = [ "kubelet.service" ];
+        path = with pkgs; [ docker ];
+        preStart = ''
+          ${concatMapStrings (img: ''
+            echo "Seeding docker image: ${img}"
+            docker load <${img}
+          '') cfg.seedDockerImages}
+        '';
+        script = "echo Ok";
+        serviceConfig.Type = "oneshot";
+        serviceConfig.Slice = "kubernetes.slice";
+      };
+
       systemd.services.node-online = {
         wantedBy = [ "node-online.target" ];
         after = [ "flannel.target" "kubelet.target" ];