Extract running Dockershim into own file

Extract a `runDockershim` function into a file outside of `kubelet.go`.
We can use build tags to compile two separate functions... one which
actually runs dockershim and one that is a no-op.

pkg/kubelet/BUILD

@@ -13,6 +13,7 @@ go_library(
         "doc.go",
         "errors.go",
         "kubelet.go",
+        "kubelet_dockershim.go",
         "kubelet_getters.go",
         "kubelet_network.go",
         "kubelet_network_linux.go",

pkg/kubelet/dockershim/dockershim_nodocker.go

@@ -0,0 +1,3 @@
+// +build dockerless
+
+package dockershim

pkg/kubelet/kubelet.go

@@ -71,7 +71,6 @@ import (
 	"k8s.io/kubernetes/pkg/kubelet/configmap"
 	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
 	"k8s.io/kubernetes/pkg/kubelet/dockershim"
-	dockerremote "k8s.io/kubernetes/pkg/kubelet/dockershim/remote"
 	"k8s.io/kubernetes/pkg/kubelet/events"
 	"k8s.io/kubernetes/pkg/kubelet/eviction"
 	"k8s.io/kubernetes/pkg/kubelet/images"
@@ -306,46 +305,15 @@ func PreInitRuntimeService(kubeCfg *kubeletconfiginternal.KubeletConfiguration,
 
 	switch containerRuntime {
 	case kubetypes.DockerContainerRuntime:
-		// TODO: These need to become arguments to a standalone docker shim.
-		pluginSettings := dockershim.NetworkPluginSettings{
-			HairpinMode:        kubeletconfiginternal.HairpinMode(kubeCfg.HairpinMode),
-			NonMasqueradeCIDR:  nonMasqueradeCIDR,
-			PluginName:         crOptions.NetworkPluginName,
-			PluginConfDir:      crOptions.CNIConfDir,
-			PluginBinDirString: crOptions.CNIBinDir,
-			PluginCacheDir:     crOptions.CNICacheDir,
-			MTU:                int(crOptions.NetworkPluginMTU),
-		}
-
-		// Create and start the CRI shim running as a grpc server.
-		streamingConfig := getStreamingConfig(kubeCfg, kubeDeps, crOptions)
-		ds, err := dockershim.NewDockerService(kubeDeps.DockerClientConfig, crOptions.PodSandboxImage, streamingConfig,
-			&pluginSettings, runtimeCgroups, kubeCfg.CgroupDriver, crOptions.DockershimRootDirectory, !crOptions.RedirectContainerStreaming)
-		if err != nil {
-			return err
-		}
-		if crOptions.RedirectContainerStreaming {
-			kubeDeps.criHandler = ds
-		}
-
-		// The unix socket for kubelet <-> dockershim communication, dockershim start before runtime service init.
-		klog.V(5).Infof("RemoteRuntimeEndpoint: %q, RemoteImageEndpoint: %q",
+		runDockershim(
+			kubeCfg,
+			kubeDeps,
+			crOptions,
+			runtimeCgroups,
 			remoteRuntimeEndpoint,
-			remoteImageEndpoint)
-		klog.V(2).Infof("Starting the GRPC server for the docker CRI shim.")
-		dockerServer := dockerremote.NewDockerServer(remoteRuntimeEndpoint, ds)
-		if err := dockerServer.Start(); err != nil {
-			return err
-		}
-
-		// Create dockerLegacyService when the logging driver is not supported.
-		supported, err := ds.IsCRISupportedLogDriver()
-		if err != nil {
-			return err
-		}
-		if !supported {
-			kubeDeps.dockerLegacyService = ds
-		}
+			remoteImageEndpoint,
+			nonMasqueradeCIDR,
+		)
 	case kubetypes.RemoteContainerRuntime:
 		// No-op.
 		break

pkg/kubelet/kubelet_dockershim.go

@@ -0,0 +1,78 @@
+// +build !dockerless
+
+/*
+Copyright 2020 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package kubelet
+
+import (
+	"k8s.io/klog"
+
+	kubeletconfiginternal "k8s.io/kubernetes/pkg/kubelet/apis/config"
+	"k8s.io/kubernetes/pkg/kubelet/config"
+	"k8s.io/kubernetes/pkg/kubelet/dockershim"
+	dockerremote "k8s.io/kubernetes/pkg/kubelet/dockershim/remote"
+)
+
+func runDockershim(kubeCfg *kubeletconfiginternal.KubeletConfiguration,
+	kubeDeps *Dependencies,
+	crOptions *config.ContainerRuntimeOptions,
+	runtimeCgroups string,
+	remoteRuntimeEndpoint string,
+	remoteImageEndpoint string,
+	nonMasqueradeCIDR string) error {
+	pluginSettings := dockershim.NetworkPluginSettings{
+		HairpinMode:        kubeletconfiginternal.HairpinMode(kubeCfg.HairpinMode),
+		NonMasqueradeCIDR:  nonMasqueradeCIDR,
+		PluginName:         crOptions.NetworkPluginName,
+		PluginConfDir:      crOptions.CNIConfDir,
+		PluginBinDirString: crOptions.CNIBinDir,
+		PluginCacheDir:     crOptions.CNICacheDir,
+		MTU:                int(crOptions.NetworkPluginMTU),
+	}
+
+	// Create and start the CRI shim running as a grpc server.
+	streamingConfig := getStreamingConfig(kubeCfg, kubeDeps, crOptions)
+	ds, err := dockershim.NewDockerService(kubeDeps.DockerClientConfig, crOptions.PodSandboxImage, streamingConfig,
+		&pluginSettings, runtimeCgroups, kubeCfg.CgroupDriver, crOptions.DockershimRootDirectory, !crOptions.RedirectContainerStreaming)
+	if err != nil {
+		return err
+	}
+	if crOptions.RedirectContainerStreaming {
+		kubeDeps.criHandler = ds
+	}
+
+	// The unix socket for kubelet <-> dockershim communication, dockershim start before runtime service init.
+	klog.V(5).Infof("RemoteRuntimeEndpoint: %q, RemoteImageEndpoint: %q",
+		remoteRuntimeEndpoint,
+		remoteImageEndpoint)
+	klog.V(2).Infof("Starting the GRPC server for the docker CRI shim.")
+	dockerServer := dockerremote.NewDockerServer(remoteRuntimeEndpoint, ds)
+	if err := dockerServer.Start(); err != nil {
+		return err
+	}
+
+	// Create dockerLegacyService when the logging driver is not supported.
+	supported, err := ds.IsCRISupportedLogDriver()
+	if err != nil {
+		return err
+	}
+	if !supported {
+		kubeDeps.dockerLegacyService = ds
+	}
+
+	return nil
+}

pkg/kubelet/kubelet_dockershim_nodocker.go

@@ -0,0 +1,36 @@
+// +build dockerless
+
+/*
+Copyright 2020 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package kubelet
+
+import (
+	"fmt"
+	kubeletconfiginternal "k8s.io/kubernetes/pkg/kubelet/apis/config"
+	"k8s.io/kubernetes/pkg/kubelet/config"
+)
+
+func runDockershim(kubeCfg *kubeletconfiginternal.KubeletConfiguration,
+	kubeDeps *Dependencies,
+	crOptions *config.ContainerRuntimeOptions,
+	runtimeCgroups string,
+	remoteRuntimeEndpoint string,
+	remoteImageEndpoint string,
+	nonMasqueradeCIDR string) error {
+
+	return fmt.Errorf("Trying to use docker runtime, w/ Kubelet compiled w/o docker support.")
+}