Move DockerLegacyService interface out of pkg/kubelet/dockershim

DockerLegacyService interface is used throughout `pkg/kubelet`.
It used to live in the `pkg/kubelet/dockershim` package. While we
would eventually like to remove it entirely, we need to give users some form
of warning.

By including the interface in
`pkg/kubelet/legacy/logs.go`, we ensure the interface is
available to `pkg/kubelet`, even when we are building with the `dockerless`
tag (i.e. not compiling the dockershim).
While the interface always exists, there will be no implementations of the
interface when building with the `dockerless` tag. The lack of
implementations should not be an issue, as we only expect `pkg/kubelet` code
to need an implementation of the `DockerLegacyService` when we are using
docker. If we are using docker, but building with the `dockerless` tag, than
this will be just one of many things that breaks.

`pkg/kubelet/legacy` might not be the best name for the package... I'm
very open to finding a different package name or even an already
existing package.

pkg/kubelet/BUILD

@@ -62,6 +62,7 @@ go_library(
         "//pkg/kubelet/images:go_default_library",
         "//pkg/kubelet/kubeletconfig:go_default_library",
         "//pkg/kubelet/kuberuntime:go_default_library",
+        "//pkg/kubelet/legacy:go_default_library",
         "//pkg/kubelet/lifecycle:go_default_library",
         "//pkg/kubelet/logs:go_default_library",
         "//pkg/kubelet/metrics:go_default_library",
@@ -298,6 +299,7 @@ filegroup(
         "//pkg/kubelet/kubeletconfig:all-srcs",
         "//pkg/kubelet/kuberuntime:all-srcs",
         "//pkg/kubelet/leaky:all-srcs",
+        "//pkg/kubelet/legacy:all-srcs",
         "//pkg/kubelet/lifecycle:all-srcs",
         "//pkg/kubelet/logs:all-srcs",
         "//pkg/kubelet/metrics:all-srcs",

pkg/kubelet/dockershim/BUILD

@@ -51,6 +51,7 @@ go_library(
         "//pkg/kubelet/dockershim/network/kubenet:go_default_library",
         "//pkg/kubelet/kuberuntime:go_default_library",
         "//pkg/kubelet/leaky:go_default_library",
+        "//pkg/kubelet/legacy:go_default_library",
         "//pkg/kubelet/server/streaming:go_default_library",
         "//pkg/kubelet/types:go_default_library",
         "//pkg/kubelet/util/cache:go_default_library",

pkg/kubelet/dockershim/docker_legacy_service.go

@@ -32,25 +32,17 @@ import (
 	kubetypes "k8s.io/apimachinery/pkg/types"
 	"k8s.io/klog"
 	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
-	"k8s.io/kubernetes/pkg/kubelet/kuberuntime"
 
 	"k8s.io/kubernetes/pkg/kubelet/dockershim/libdocker"
 )
 
-// DockerLegacyService interface embeds some legacy methods for backward compatibility.
+// We define `DockerLegacyService` in `pkg/kubelet/legacy`, instead of in this
-// This file/interface will be removed in the near future. Do not modify or add
+// file. We make this decision because `pkg/kubelet` depends on
-// more functions.
+// `DockerLegacyService`, and we want to be able to build the `kubelet` without
-type DockerLegacyService interface {
+// relying on `github.com/docker/docker` or `pkg/kubelet/dockershim`.
-	// GetContainerLogs gets logs for a specific container.
+//
-	GetContainerLogs(context.Context, *v1.Pod, kubecontainer.ContainerID, *v1.PodLogOptions, io.Writer, io.Writer) error
+// See https://github.com/kubernetes/enhancements/blob/master/keps/sig-node/20200205-build-kubelet-without-docker.md
-
+// for details.
-	// IsCRISupportedLogDriver checks whether the logging driver used by docker is
-	// supported by native CRI integration.
-	// TODO(resouer): remove this when deprecating unsupported log driver
-	IsCRISupportedLogDriver() (bool, error)
-
-	kuberuntime.LegacyLogProvider
-}
 
 // GetContainerLogs get container logs directly from docker daemon.
 func (d *dockerService) GetContainerLogs(_ context.Context, pod *v1.Pod, containerID kubecontainer.ContainerID, logOptions *v1.PodLogOptions, stdout, stderr io.Writer) error {

pkg/kubelet/dockershim/docker_service.go

@@ -40,6 +40,7 @@ import (
 	"k8s.io/kubernetes/pkg/kubelet/dockershim/network/cni"
 	"k8s.io/kubernetes/pkg/kubelet/dockershim/network/hostport"
 	"k8s.io/kubernetes/pkg/kubelet/dockershim/network/kubenet"
+	"k8s.io/kubernetes/pkg/kubelet/legacy"
 	"k8s.io/kubernetes/pkg/kubelet/server/streaming"
 	"k8s.io/kubernetes/pkg/kubelet/util/cache"
 
@@ -97,7 +98,7 @@ type DockerService interface {
 	http.Handler
 
 	// For supporting legacy features.
-	DockerLegacyService
+	legacy.DockerLegacyService
 }
 
 // NetworkPluginSettings is the subset of kubelet runtime args we pass

pkg/kubelet/kubelet.go

@@ -70,12 +70,12 @@ import (
 	"k8s.io/kubernetes/pkg/kubelet/config"
 	"k8s.io/kubernetes/pkg/kubelet/configmap"
 	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
-	"k8s.io/kubernetes/pkg/kubelet/dockershim"
 	"k8s.io/kubernetes/pkg/kubelet/events"
 	"k8s.io/kubernetes/pkg/kubelet/eviction"
 	"k8s.io/kubernetes/pkg/kubelet/images"
 	"k8s.io/kubernetes/pkg/kubelet/kubeletconfig"
 	"k8s.io/kubernetes/pkg/kubelet/kuberuntime"
+	"k8s.io/kubernetes/pkg/kubelet/legacy"
 	"k8s.io/kubernetes/pkg/kubelet/lifecycle"
 	"k8s.io/kubernetes/pkg/kubelet/logs"
 	"k8s.io/kubernetes/pkg/kubelet/metrics"
@@ -231,7 +231,7 @@ type Dependencies struct {
 	RemoteRuntimeService    internalapi.RuntimeService
 	RemoteImageService      internalapi.ImageManagerService
 	criHandler              http.Handler
-	dockerLegacyService     dockershim.DockerLegacyService
+	dockerLegacyService     legacy.DockerLegacyService
 	// remove it after cadvisor.UsingLegacyCadvisorStats dropped.
 	useLegacyCadvisorStats bool
 }
@@ -1129,7 +1129,7 @@ type Kubelet struct {
 
 	// dockerLegacyService contains some legacy methods for backward compatibility.
 	// It should be set only when docker is using non json-file logging driver.
-	dockerLegacyService dockershim.DockerLegacyService
+	dockerLegacyService legacy.DockerLegacyService
 
 	// StatsProvider provides the node and the container stats.
 	*stats.StatsProvider

pkg/kubelet/legacy/BUILD

@@ -0,0 +1,27 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["logs.go"],
+    importpath = "k8s.io/kubernetes/pkg/kubelet/legacy",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//pkg/kubelet/container:go_default_library",
+        "//pkg/kubelet/kuberuntime:go_default_library",
+        "//staging/src/k8s.io/api/core/v1:go_default_library",
+    ],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+    visibility = ["//visibility:public"],
+)

pkg/kubelet/legacy/logs.go

@@ -0,0 +1,53 @@
+/*
+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 legacy
+
+import (
+	"context"
+	"io"
+
+	"k8s.io/api/core/v1"
+	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
+	"k8s.io/kubernetes/pkg/kubelet/kuberuntime"
+)
+
+// DockerLegacyService interface is used throughout `pkg/kubelet`.
+// It used to live in the `pkg/kubelet/dockershim` package. While we
+// would eventually like to remove it entirely, we need to give users some form
+// of warning.
+//
+// By including the interface in
+// `pkg/kubelet/legacy/logs.go`, we ensure the interface is
+// available to `pkg/kubelet`, even when we are building with the `dockerless`
+// tag (i.e. not compiling the dockershim).
+// While the interface always exists, there will be no implementations of the
+// interface when building with the `dockerless` tag. The lack of
+// implementations should not be an issue, as we only expect `pkg/kubelet` code
+// to need an implementation of the `DockerLegacyService` when we are using
+// docker. If we are using docker, but building with the `dockerless` tag, than
+// this will be just one of many things that breaks.
+type DockerLegacyService interface {
+	// GetContainerLogs gets logs for a specific container.
+	GetContainerLogs(context.Context, *v1.Pod, kubecontainer.ContainerID, *v1.PodLogOptions, io.Writer, io.Writer) error
+
+	// IsCRISupportedLogDriver checks whether the logging driver used by docker is
+	// supported by native CRI integration.
+	// TODO(resouer): remove this when deprecating unsupported log driver
+	IsCRISupportedLogDriver() (bool, error)
+
+	kuberuntime.LegacyLogProvider
+}