allows controller to be configured via environment variable

README.md

@@ -5,6 +5,18 @@ Out of tree implementation of https://github.com/kubernetes/enhancements/tree/ma
 It allows users to use an ipam-controller that allocates IP ranges to Nodes, setting the node.spec.PodCIDRs fields.
 The ipam-controller is configured via CRDs
 
+## Config
+
+* `apiserver` - The address of the Kubernetes API server. Overrides any value in kubeconfig. Only required if out-of-cluster. (Env: `IPAM_API_SERVER_URL`)
+* `kubeconfig` - Path to a kubeconfig. Only required if out-of-cluster. (Env: `IPAM_KUBECONFIG`)
+* `health-probe-address` - Specifies the TCP address for the health server to listen on. (Env: `IPAM_HEALTH_PROBE_ADDR`)
+* `enable-leader-election` - Enable leader election for the controller manager. Ensures there is only one active controller manager. (Env: `IPAM_ENABLE_LEADER_ELECTION`)
+* `leader-elect-lease-duration` - Duration that non-leader candidates will wait to force acquire leadership (duration string). (Env: `IPAM_LEASE_DURATION`)
+* `leader-elect-renew-deadline` - Interval between attempts by the acting master to renew a leadership slot before it stops leading (duration string). (Env: `IPAM_RENEW_DEADLINE`)
+* `leader-elect-retry-period` - Duration the clients should wait between attempting acquisition and renewal of a leadership (duration string). (Env: `IPAM_RESOURCE_LOCK`)
+* `leader-elect-resource-lock` - The type of resource object that is used for locking. Supported options are 'leases', 'endpoints', 'configmaps'. (Env: `IPAM_RESOURCE_LOCK_NAME`)
+* `leader-elect-resource-name` - The name of the resource object that is used for locking. (Env: `IPAM_RESOURCE_NAME`)
+
 ## Build
 
 To build the binary for node-ipam-controller:
@@ -56,3 +68,4 @@ Install node-ipam-controller in the cluster via helm:
 ```sh
 helm install node-ipam-controller ./charts/node-ipam-controller --create-namespace --namespace nodeipam --set image.tag=local
 ```
+

go.mod

@@ -5,6 +5,7 @@ go 1.21
 require (
 	github.com/evanphx/json-patch v5.6.0+incompatible
 	github.com/golangci/golangci-lint v1.54.2
+	github.com/jessevdk/go-flags v1.6.1
 	github.com/onsi/ginkgo/v2 v2.13.2
 	github.com/onsi/gomega v1.30.0
 	github.com/stretchr/testify v1.8.4
@@ -210,7 +211,7 @@ require (
 	golang.org/x/net v0.17.0 // indirect
 	golang.org/x/oauth2 v0.8.0 // indirect
 	golang.org/x/sync v0.4.0 // indirect
-	golang.org/x/sys v0.14.0 // indirect
+	golang.org/x/sys v0.21.0 // indirect
 	golang.org/x/term v0.13.0 // indirect
 	golang.org/x/text v0.13.0 // indirect
 	golang.org/x/time v0.3.0 // indirect

go.sum

@@ -337,6 +337,8 @@ github.com/imdario/mergo v0.3.6/go.mod h1:2EnlNZ0deacrJVfApfmtdGgDfMuh/nq6Ok1EcJ
 github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
 github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
 github.com/jessevdk/go-flags v1.4.0/go.mod h1:4FA24M0QyGHXBuZZK/XkWh8h0e1EYbRYJSGM75WSRxI=
+github.com/jessevdk/go-flags v1.6.1 h1:Cvu5U8UGrLay1rZfv/zP7iLpSHGUZ/Ou68T0iX1bBK4=
+github.com/jessevdk/go-flags v1.6.1/go.mod h1:Mk8T1hIAWpOiJiHa9rJASDK2UGWji0EuPGBnNLMooyc=
 github.com/jgautheron/goconst v1.5.1 h1:HxVbL1MhydKs8R8n/HE5NPvzfaYmQJA3o879lE4+WcM=
 github.com/jgautheron/goconst v1.5.1/go.mod h1:aAosetZ5zaeC/2EfMeRswtxUFBpe2Hr7HzkgX4fanO4=
 github.com/jingyugao/rowserrcheck v1.1.1 h1:zibz55j/MJtLsjP1OF4bSdgXxwL1b+Vn7Tjzq7gFzUs=
@@ -824,6 +826,8 @@ golang.org/x/sys v0.4.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.14.0 h1:Vz7Qs629MkJkGyHxUlRHizWJRG2j8fbQKjELVSNhy7Q=
 golang.org/x/sys v0.14.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.21.0 h1:rF+pYz3DAGSQAxAu1CbC7catZg4ebC4UIeIhKxBZvws=
+golang.org/x/sys v0.21.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/term v0.1.0/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=

main.go

@@ -25,53 +25,64 @@ import (
 	"os"
 	"time"
 
-	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"github.com/jessevdk/go-flags"
+	"k8s.io/client-go/tools/clientcmd"
 	"k8s.io/component-base/logs"
-	logsapi "k8s.io/component-base/logs/api/v1"
-	clientset "sigs.k8s.io/node-ipam-controller/pkg/client/clientset/versioned"
-	informers "sigs.k8s.io/node-ipam-controller/pkg/client/informers/externalversions"
-	"sigs.k8s.io/node-ipam-controller/pkg/controller/ipam"
+
 	"sigs.k8s.io/node-ipam-controller/pkg/leaderelection"
 	"sigs.k8s.io/node-ipam-controller/pkg/signals"
 
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	kubeinformers "k8s.io/client-go/informers"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/rest"
+	logsapi "k8s.io/component-base/logs/api/v1"
+	clientset "sigs.k8s.io/node-ipam-controller/pkg/client/clientset/versioned"
+	informers "sigs.k8s.io/node-ipam-controller/pkg/client/informers/externalversions"
+	"sigs.k8s.io/node-ipam-controller/pkg/controller/ipam"
 
 	// 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/tools/clientcmd"
 	_ "k8s.io/component-base/logs/json/register"
 	"k8s.io/klog/v2"
 )
 
-func main() {
-	var (
-		apiServerURL         string
-		kubeconfig           string
-		healthProbeAddr      string
-		enableLeaderElection bool
-		leaseDuration        time.Duration
-		renewDeadline        time.Duration
-		retryPeriod          time.Duration
-		resourceLock         string
-		resourceName         string
-	)
+type Config struct {
+	ApiServerURL         string        `long:"apiserver" description:"The address of the Kubernetes API server. Overrides any value in kubeconfig. Only required if out-of-cluster." env:"IPAM_API_SERVER_URL"`
+	Kubeconfig           string        `long:"kubeconfig" description:"Path to a kubeconfig. Only required if out-of-cluster." env:"IPAM_KUBECONFIG"`
+	HealthProbeAddr      string        `long:"health-probe-address" default:":8081" description:"Specifies the TCP address for the health server to listen on." env:"IPAM_HEALTH_PROBE_ADDR"`
+	EnableLeaderElection bool          `long:"enable-leader-election" description:"Enable leader election for the controller manager. Ensures there is only one active controller manager." env:"IPAM_ENABLE_LEADER_ELECTION"`
+	LeaseDuration        time.Duration `long:"leader-elect-lease-duration" default:"15s" description:"Duration that non-leader candidates will wait to force acquire leadership (duration string)." env:"IPAM_LEASE_DURATION"`
+	RenewDeadline        time.Duration `long:"leader-elect-renew-deadline" default:"10s" description:"Interval between attempts by the acting master to renew a leadership slot before it stops leading (duration string)." env:"IPAM_RENEW_DEADLINE"`
+	RetryPeriod          time.Duration `long:"leader-elect-retry-period" default:"2s" description:"Duration the clients should wait between attempting acquisition and renewal of a leadership (duration string)." env:"IPAM_RESOURCE_LOCK"`
+	ResourceLock         string        `long:"leader-elect-resource-lock" default:"leases" description:"The type of resource object that is used for locking. Supported options are 'leases', 'endpoints', 'configmaps'." env:"IPAM_RESOURCE_LOCK_NAME"`
+	ResourceName         string        `long:"leader-elect-resource-name" default:"node-ipam-controller" description:"The name of the resource object that is used for locking." env:"IPAM_RESOURCE_NAME"`
+}
 
-	flag.StringVar(&kubeconfig, "kubeconfig", "", "Path to a kubeconfig. Only required if out-of-cluster.")
-	flag.StringVar(&apiServerURL, "apiserver", "", "The address of the Kubernetes API server. Overrides any value in kubeconfig. Only required if out-of-cluster.")
-	flag.StringVar(&healthProbeAddr, "health-probe-address", ":8081", "Specifies the TCP address for the health server to listen on.")
-	flag.BoolVar(&enableLeaderElection, "enable-leader-election", true, "Enable leader election for the controller manager. Ensures there is only one active controller manager.")
-	flag.DurationVar(&leaseDuration, "leader-elect-lease-duration", 15*time.Second, "Duration that non-leader candidates will wait to force acquire leadership (duration string).")
-	flag.DurationVar(&renewDeadline, "leader-elect-renew-deadline", 10*time.Second, "Interval between attempts by the acting master to renew a leadership slot before it stops leading (duration string).")
-	flag.DurationVar(&retryPeriod, "leader-elect-retry-period", 2*time.Second, "Duration the clients should wait between attempting acquisition and renewal of a leadership (duration string).")
-	flag.StringVar(&resourceLock, "leader-elect-resource-lock", "leases", "The type of resource object that is used for locking. Supported options are 'leases', 'endpoints', 'configmaps'.")
-	flag.StringVar(&resourceName, "leader-elect-resource-name", "node-ipam-controller", "The name of the resource object that is used for locking.")
+func (c *Config) Load() error {
+	// allows using true/false in the parameters
+	_, err := flags.NewParser(c, flags.Default|flags.AllowBoolValues).ParseArgs(os.Args)
+	if err != nil {
+		return err
+	}
+	return nil
+}
 
+func main() {
 	c := logsapi.NewLoggingConfiguration()
 	logsapi.AddGoFlags(c, flag.CommandLine)
-	flag.Parse()
+
+	config := Config{EnableLeaderElection: true}
+	err := config.Load()
+	if err != nil {
+		var flagError *flags.Error
+		errors.As(err, &flagError)
+		if flagError.Type == flags.ErrHelp {
+			os.Exit(0)
+		}
+		os.Exit(22)
+	}
 
 	logs.InitLogs()
 	if err := logsapi.ValidateAndApply(c, nil); err != nil {
@@ -82,8 +93,8 @@ func main() {
 	defer cancel()
 	logger := klog.FromContext(ctx)
 
-	server := startHealthProbeServer(healthProbeAddr, logger)
-	cfg, err := clientcmd.BuildConfigFromFlags(apiServerURL, kubeconfig)
+	server := startHealthProbeServer(config.HealthProbeAddr, logger)
+	cfg, err := clientcmd.BuildConfigFromFlags(config.ApiServerURL, config.Kubeconfig)
 	if err != nil {
 		logger.Error(err, "failed to build kubeconfig")
 		klog.FlushAndExit(klog.ExitFlushTimeout, 1)
@@ -95,14 +106,14 @@ func main() {
 		klog.FlushAndExit(klog.ExitFlushTimeout, 1)
 	}
 
-	if enableLeaderElection {
+	if config.EnableLeaderElection {
 		logger.Info("Leader election is enabled.")
 		leaderelection.StartLeaderElection(ctx, kubeClient, cfg, logger, cancel, runControllers, leaderelection.Config{
-			LeaseDuration: leaseDuration,
-			RenewDeadline: renewDeadline,
-			RetryPeriod:   retryPeriod,
-			ResourceLock:  resourceLock,
-			ResourceName:  resourceName,
+			LeaseDuration: config.LeaseDuration,
+			RenewDeadline: config.RenewDeadline,
+			RetryPeriod:   config.RetryPeriod,
+			ResourceLock:  config.ResourceLock,
+			ResourceName:  config.ResourceName,
 		})
 	} else {
 		logger.Info("Leader election is disabled.")