manager.go

/*
Copyright 2024.

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 manager

import (
	"context"
	"crypto/tls"
	"fmt"

	// Import all Kubernetes client auth plugins (e.g. Azure, GCP, OIDC, etc.)
	// to ensure that exec-entrypoint and run can make use of them.
	_ "k8s.io/client-go/plugin/pkg/client/auth"
	"k8s.io/client-go/rest"

	"k8s.io/apimachinery/pkg/runtime"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/cache"
	"sigs.k8s.io/controller-runtime/pkg/controller"
	"sigs.k8s.io/controller-runtime/pkg/healthz"
	"sigs.k8s.io/controller-runtime/pkg/metrics/filters"
	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"
	"sigs.k8s.io/controller-runtime/pkg/webhook"

	"github.com/go-logr/logr"
	"github.com/k-orc/openstack-resource-controller/internal/controllers/export"
	// +kubebuilder:scaffold:imports
)

type Options struct {
	MetricsAddr          string
	EnableLeaderElection bool
	ProbeAddr            string
	SecureMetrics        bool
	EnableHTTP2          bool
	TLSOpts              []func(*tls.Config)
	ScopeCacheMaxSize    int
	WatchNamespaces      []string
}

func Run(ctx context.Context, opts *Options, restConfig *rest.Config, scheme *runtime.Scheme, setupLog, log logr.Logger, controllers []export.Controller) error {
	// if the enable-http2 flag is false (the default), http/2 should be disabled
	// due to its vulnerabilities. More specifically, disabling http/2 will
	// prevent from being vulnerable to the HTTP/2 Stream Cancellation and
	// Rapid Reset CVEs. For more information see:
	// - https://github.com/advisories/GHSA-qppj-fm5r-hxr3
	// - https://github.com/advisories/GHSA-4374-p667-p6c8
	disableHTTP2 := func(c *tls.Config) {
		setupLog.Info("disabling http/2")
		c.NextProtos = []string{"http/1.1"}
	}

	if !opts.EnableHTTP2 {
		opts.TLSOpts = append(opts.TLSOpts, disableHTTP2)
	}

	webhookServer := webhook.NewServer(webhook.Options{
		TLSOpts: opts.TLSOpts,
	})

	// Metrics endpoint is enabled in 'config/default/kustomization.yaml'. The Metrics options configure the server.
	// More info:
	// - https://pkg.go.dev/sigs.k8s.io/controller-runtime@v0.18.4/pkg/metrics/server
	// - https://book.kubebuilder.io/reference/metrics.html
	metricsServerOptions := metricsserver.Options{
		BindAddress:   opts.MetricsAddr,
		SecureServing: opts.SecureMetrics,
		// TODO(user): TLSOpts is used to allow configuring the TLS config used for the server. If certificates are
		// not provided, self-signed certificates will be generated by default. This option is not recommended for
		// production environments as self-signed certificates do not offer the same level of trust and security
		// as certificates issued by a trusted Certificate Authority (CA). The primary risk is potentially allowing
		// unauthorized access to sensitive metrics data. Consider replacing with CertDir, CertName, and KeyName
		// to provide certificates, ensuring the server communicates using trusted and secure certificates.
		TLSOpts: opts.TLSOpts,
	}

	if opts.SecureMetrics {
		// FilterProvider is used to protect the metrics endpoint with authn/authz.
		// These configurations ensure that only authorized users and service accounts
		// can access the metrics endpoint. The RBAC are configured in 'config/rbac/kustomization.yaml'. More info:
		// https://pkg.go.dev/sigs.k8s.io/controller-runtime@v0.18.4/pkg/metrics/filters#WithAuthenticationAndAuthorization
		metricsServerOptions.FilterProvider = filters.WithAuthenticationAndAuthorization
	}

	var watchNamespaces map[string]cache.Config
	if len(opts.WatchNamespaces) > 0 {
		watchNamespaces = make(map[string]cache.Config, len(watchNamespaces))
		for i := range opts.WatchNamespaces {
			watchNamespaces[opts.WatchNamespaces[i]] = cache.Config{}
		}
	}

	mgr, err := ctrl.NewManager(restConfig, ctrl.Options{
		Scheme:                 scheme,
		Metrics:                metricsServerOptions,
		WebhookServer:          webhookServer,
		HealthProbeBindAddress: opts.ProbeAddr,
		Logger:                 log,

		Cache: cache.Options{
			DefaultNamespaces: watchNamespaces,
		},

		LeaderElection:   opts.EnableLeaderElection,
		LeaderElectionID: "f35396c5.k-orc.cloud",
		// LeaderElectionReleaseOnCancel defines if the leader should step down voluntarily
		// when the Manager ends. This requires the binary to immediately end when the
		// Manager is stopped, otherwise, this setting is unsafe. Setting this significantly
		// speeds up voluntary leader transitions as the new leader don't have to wait
		// LeaseDuration time first.
		//
		// In the default scaffold provided, the program ends immediately after
		// the manager stops, so would be fine to enable this option. However,
		// if you are doing or is intended to do any operation such as perform cleanups
		// after the manager stops then its usage might be unsafe.
		LeaderElectionReleaseOnCancel: true,
	})
	if err != nil {
		return fmt.Errorf("unable to start manager: %w", err)
	}

	// +kubebuilder:scaffold:builder

	if err := mgr.AddHealthzCheck("healthz", healthz.Ping); err != nil {
		return fmt.Errorf("unable to set up health check: %w", err)
	}
	if err := mgr.AddReadyzCheck("readyz", healthz.Ping); err != nil {
		return fmt.Errorf("unable to set up ready check: %w", err)
	}

	for _, c := range controllers {
		if err := c.SetupWithManager(ctx, mgr, controller.Options{}); err != nil {
			return fmt.Errorf("unable to create %s controller: %w", c.GetName(), err)
		}
	}

	setupLog.Info("starting manager")
	if err := mgr.Start(ctx); err != nil {
		return fmt.Errorf("problem running manager: %w", err)
	}

	return nil
}