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gardener_scheduler.go
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gardener_scheduler.go
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// Copyright (c) 2019 SAP SE or an SAP affiliate company. All rights reserved. This file is licensed under the Apache Software License, v. 2 except as noted otherwise in the LICENSE file
//
// 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 app
import (
"context"
"errors"
"fmt"
"os"
"github.com/gardener/gardener/cmd/utils"
gardencorev1beta1 "github.com/gardener/gardener/pkg/apis/core/v1beta1"
"github.com/gardener/gardener/pkg/client/kubernetes"
"github.com/gardener/gardener/pkg/client/kubernetes/clientmap"
clientmapbuilder "github.com/gardener/gardener/pkg/client/kubernetes/clientmap/builder"
"github.com/gardener/gardener/pkg/client/kubernetes/clientmap/keys"
gardenmetrics "github.com/gardener/gardener/pkg/controllerutils/metrics"
"github.com/gardener/gardener/pkg/features"
"github.com/gardener/gardener/pkg/healthz"
"github.com/gardener/gardener/pkg/logger"
"github.com/gardener/gardener/pkg/scheduler"
"github.com/gardener/gardener/pkg/scheduler/apis/config"
configloader "github.com/gardener/gardener/pkg/scheduler/apis/config/loader"
"github.com/gardener/gardener/pkg/scheduler/apis/config/validation"
shootcontroller "github.com/gardener/gardener/pkg/scheduler/controller/shoot"
schedulerfeatures "github.com/gardener/gardener/pkg/scheduler/features"
"github.com/gardener/gardener/pkg/server"
"github.com/prometheus/client_golang/prometheus/promhttp"
"github.com/sirupsen/logrus"
"github.com/spf13/cobra"
"github.com/spf13/pflag"
kubernetesclientset "k8s.io/client-go/kubernetes"
"k8s.io/client-go/tools/leaderelection"
"k8s.io/client-go/tools/record"
"k8s.io/component-base/version/verflag"
)
// Options has all the context and parameters needed to run a GardenerScheduler.
type Options struct {
// ConfigFile is the location of the GardenerScheduler's configuration file.
ConfigFile string
config *config.SchedulerConfiguration
}
// AddFlags adds flags for a specific Scheduler to the specified FlagSet.
func (o *Options) AddFlags(fs *pflag.FlagSet) {
fs.StringVar(&o.ConfigFile, "config", o.ConfigFile, "The path to the configuration file.")
}
// Validate validates all the required options.
func (o *Options) validate(args []string) error {
if len(o.ConfigFile) == 0 {
return fmt.Errorf("missing GardenerScheduler config file")
}
if len(args) != 0 {
return errors.New("arguments are not supported")
}
return nil
}
func (o *Options) run(ctx context.Context) error {
if len(o.ConfigFile) > 0 {
c, err := configloader.LoadFromFile(o.ConfigFile)
if err != nil {
return err
}
o.config = c
}
// Add feature flags
if err := schedulerfeatures.FeatureGate.SetFromMap(o.config.FeatureGates); err != nil {
return err
}
kubernetes.UseCachedRuntimeClients = schedulerfeatures.FeatureGate.Enabled(features.CachedRuntimeClients)
gardener, err := NewGardenerScheduler(ctx, o.config)
if err != nil {
return err
}
return gardener.Run(ctx)
}
// NewCommandStartGardenerScheduler creates a *cobra.Command object with default parameters
func NewCommandStartGardenerScheduler() *cobra.Command {
opts := &Options{
config: new(config.SchedulerConfiguration),
}
cmd := &cobra.Command{
Use: "gardener-scheduler",
Short: "Launch the Gardener scheduler",
Long: `The Gardener scheduler is a controller that tries to find the best matching seed cluster for a shoot. The scheduler takes the cloud provider and the distance between the seed (hosting the control plane) and the shoot cluster region into account.`,
RunE: func(cmd *cobra.Command, args []string) error {
verflag.PrintAndExitIfRequested()
if err := opts.validate(args); err != nil {
return err
}
return opts.run(cmd.Context())
},
}
flags := cmd.Flags()
verflag.AddFlags(flags)
opts.AddFlags(flags)
return cmd
}
// GardenerScheduler represents all the parameters required to start the
// Gardener scheduler.
type GardenerScheduler struct {
Config *config.SchedulerConfiguration
Identity *gardencorev1beta1.Gardener
GardenerNamespace string
ClientMap clientmap.ClientMap
Logger *logrus.Logger
Recorder record.EventRecorder
LeaderElection *leaderelection.LeaderElectionConfig
}
// NewGardenerScheduler is the main entry point of instantiating a new Gardener Scheduler.
func NewGardenerScheduler(ctx context.Context, cfg *config.SchedulerConfiguration) (*GardenerScheduler, error) {
// validate the configuration
if err := validation.ValidateConfiguration(cfg); err != nil {
return nil, err
}
// Initialize logger
logger := logger.NewLogger(cfg.LogLevel)
logger.Info("Starting Gardener scheduler ...")
logger.Infof("Feature Gates: %s", schedulerfeatures.FeatureGate.String())
// Prepare a Kubernetes client object for the Garden cluster which contains all the Clientsets
// that can be used to access the Kubernetes API.
if kubeconfig := os.Getenv("KUBECONFIG"); kubeconfig != "" {
cfg.ClientConnection.Kubeconfig = kubeconfig
}
restCfg, err := kubernetes.RESTConfigFromClientConnectionConfiguration(&cfg.ClientConnection, nil)
if err != nil {
return nil, err
}
clientMap, err := clientmapbuilder.
NewDelegatingClientMapBuilder().
WithGardenClientMapBuilder(clientmapbuilder.NewGardenClientMapBuilder().WithRESTConfig(restCfg)).
WithLogger(logger).
Build()
if err != nil {
return nil, fmt.Errorf("failed to build ClientMap: %w", err)
}
k8sGardenClient, err := clientMap.GetClient(ctx, keys.ForGarden())
if err != nil {
return nil, fmt.Errorf("failed to get garden client: %w", err)
}
// Set up leader election if enabled and prepare event recorder.
var (
leaderElectionConfig *leaderelection.LeaderElectionConfig
recorder = utils.CreateRecorder(k8sGardenClient.Kubernetes(), "gardener-scheduler")
)
if cfg.LeaderElection.LeaderElect {
k8sGardenClientLeaderElection, err := kubernetesclientset.NewForConfig(restCfg)
if err != nil {
return nil, fmt.Errorf("failed to create garden client for leader election: %w", err)
}
leaderElectionConfig, err = utils.MakeLeaderElectionConfig(
cfg.LeaderElection.LeaderElectionConfiguration,
cfg.LeaderElection.LockObjectNamespace,
cfg.LeaderElection.LockObjectName,
k8sGardenClientLeaderElection,
recorder,
)
if err != nil {
return nil, err
}
}
return &GardenerScheduler{
Config: cfg,
ClientMap: clientMap,
Logger: logger,
Recorder: recorder,
LeaderElection: leaderElectionConfig,
}, nil
}
// Run runs the Gardener Scheduler. This should never exit.
func (g *GardenerScheduler) Run(ctx context.Context) error {
controllerCtx, controllerCancel := context.WithCancel(ctx)
defer controllerCancel()
// Prepare a reusable run function.
run := func(ctx context.Context) {
g.startScheduler(ctx)
}
// Initialize /healthz manager.
healthManager := healthz.NewDefaultHealthz()
healthManager.Start()
// Start HTTP server.
go server.
NewBuilder().
WithBindAddress(g.Config.Server.HTTP.BindAddress).
WithPort(g.Config.Server.HTTP.Port).
WithHandler("/metrics", promhttp.Handler()).
WithHandlerFunc("/healthz", healthz.HandlerFunc(healthManager)).
Build().
Start(ctx)
leaderElectionCtx, leaderElectionCancel := context.WithCancel(context.Background())
// If leader election is enabled, run via LeaderElector until done and exit.
if g.LeaderElection != nil {
g.LeaderElection.Callbacks = leaderelection.LeaderCallbacks{
OnStartedLeading: func(_ context.Context) {
g.Logger.Info("Acquired leadership, starting scheduler.")
run(controllerCtx)
leaderElectionCancel()
},
OnStoppedLeading: func() {
g.Logger.Info("Lost leadership, terminating.")
controllerCancel()
},
}
leaderElector, err := leaderelection.NewLeaderElector(*g.LeaderElection)
if err != nil {
return fmt.Errorf("couldn't create leader elector: %v", err)
}
leaderElector.Run(leaderElectionCtx)
return nil
}
// Leader election is disabled, thus run directly until done.
leaderElectionCancel()
run(controllerCtx)
return nil
}
func (g *GardenerScheduler) startScheduler(ctx context.Context) {
if err := g.ClientMap.Start(ctx.Done()); err != nil {
panic(fmt.Errorf("failed to start ClientMap: %+v", err))
}
shootScheduler, err := shootcontroller.NewGardenerScheduler(ctx, g.ClientMap, g.Config, g.Recorder)
if err != nil {
panic(fmt.Errorf("failed to create shoot scheduler controller: %+v", err))
}
// Initialize the Controller metrics collection.
gardenmetrics.RegisterControllerMetrics(
scheduler.ControllerWorkerSum,
scheduler.ScrapeFailures,
shootScheduler,
)
go shootScheduler.Run(ctx)
// Shutdown handling
<-ctx.Done()
logger.Logger.Infof("I have received a stop signal and will no longer watch events of the Garden API group.")
logger.Logger.Infof("Bye Bye!")
}