mirror of
https://github.com/k3s-io/kubernetes.git
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110 lines
3.6 KiB
Go
110 lines
3.6 KiB
Go
/*
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Copyright 2014 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// The kubelet binary is responsible for maintaining a set of containers on a particular host VM.
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// It syncs data from both configuration file(s) as well as from a quorum of etcd servers.
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// It then queries Docker to see what is currently running. It synchronizes the configuration data,
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// with the running set of containers by starting or stopping Docker containers.
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package main
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import (
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"fmt"
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"os"
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"github.com/spf13/pflag"
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utilfeature "k8s.io/apiserver/pkg/util/feature"
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"k8s.io/apiserver/pkg/util/flag"
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"k8s.io/apiserver/pkg/util/logs"
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"k8s.io/kubernetes/cmd/kubelet/app"
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"k8s.io/kubernetes/cmd/kubelet/app/options"
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_ "k8s.io/kubernetes/pkg/client/metrics/prometheus" // for client metric registration
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_ "k8s.io/kubernetes/pkg/version/prometheus" // for version metric registration
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"k8s.io/kubernetes/pkg/version/verflag"
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)
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func die(err error) {
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fmt.Fprintf(os.Stderr, "error: %v\n", err)
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os.Exit(1)
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}
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func main() {
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// construct KubeletFlags object and register command line flags mapping
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kubeletFlags := options.NewKubeletFlags()
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kubeletFlags.AddFlags(pflag.CommandLine)
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// construct KubeletConfiguration object and register command line flags mapping
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defaultConfig, err := options.NewKubeletConfiguration()
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if err != nil {
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die(err)
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}
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options.AddKubeletConfigFlags(pflag.CommandLine, defaultConfig)
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// parse the command line flags into the respective objects
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flag.InitFlags()
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// initialize logging and defer flush
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logs.InitLogs()
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defer logs.FlushLogs()
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// short-circuit on verflag
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verflag.PrintAndExitIfRequested()
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// TODO(mtaufen): won't need this this once dynamic config is GA
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// set feature gates so we can check if dynamic config is enabled
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if err := utilfeature.DefaultFeatureGate.Set(defaultConfig.FeatureGates); err != nil {
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die(err)
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}
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// validate the initial KubeletFlags, to make sure the dynamic-config-related flags aren't used unless the feature gate is on
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if err := options.ValidateKubeletFlags(kubeletFlags); err != nil {
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die(err)
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}
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// bootstrap the kubelet config controller, app.BootstrapKubeletConfigController will check
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// feature gates and only turn on relevant parts of the controller
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kubeletConfig, kubeletConfigController, err := app.BootstrapKubeletConfigController(
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defaultConfig, kubeletFlags.InitConfigDir, kubeletFlags.DynamicConfigDir)
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if err != nil {
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die(err)
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}
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// construct a KubeletServer from kubeletFlags and kubeletConfig
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kubeletServer := &options.KubeletServer{
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KubeletFlags: *kubeletFlags,
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KubeletConfiguration: *kubeletConfig,
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}
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// use kubeletServer to construct the default KubeletDeps
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kubeletDeps, err := app.UnsecuredDependencies(kubeletServer)
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if err != nil {
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die(err)
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}
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// add the kubelet config controller to kubeletDeps
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kubeletDeps.KubeletConfigController = kubeletConfigController
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// start the experimental docker shim, if enabled
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if kubeletFlags.ExperimentalDockershim {
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if err := app.RunDockershim(kubeletConfig, &kubeletFlags.ContainerRuntimeOptions); err != nil {
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die(err)
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}
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}
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// run the kubelet
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if err := app.Run(kubeletServer, kubeletDeps); err != nil {
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die(err)
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}
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}
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