Add preflight checks

CONTRIBUTING.md

@@ -1,12 +1,16 @@
 [comment]: # ( Copyright Contributors to the Open Cluster Management project )**Table of Contents**
 
 - [Contributing guidelines](#contributing-guidelines)
-    - [Terms](#terms)
-    - [Certificate of Origin](#certificate-of-origin)
-    - [Contributing a patch](#contributing-a-patch)
-    - [Issue and pull request management](#issue-and-pull-request-management)
-    - [Requirements](#requirements)
-    - [Develop new commands](#Develop-new-commands)
+  - [Terms](#terms)
+  - [Certificate of Origin](#certificate-of-origin)
+  - [Contributing a patch](#contributing-a-patch)
+  - [Issue and pull request management](#issue-and-pull-request-management)
+- [Requirements](#requirements)
+- [Develop new commands](#develop-new-commands)
+  - [Resources](#resources)
+  - [Client](#client)
+  - [Unit tests](#unit-tests)
+  - [E2E tests](#e2e-tests)
 
 # Contributing guidelines
 
@@ -27,6 +31,7 @@ By contributing to this project, you agree to the Developer Certificate of Origi
 ## Issue and pull request management
 
 Anyone can comment on issues and submit reviews for pull requests. In order to be assigned an issue or pull request, you can leave a `/assign <your Github ID>` comment on the issue or pull request.
+
 # Requirements
 
 - Go 1.17
@@ -43,18 +48,17 @@ clusteradm <cmd> [subcmd] [flags]
 - Each command must support the flag `--dry-run`.
 - The command uses [klog V2](https://github.com/kubernetes/klog) as logging package. All messages must be using `klog.V(x)`, in rare exception `klog.Error` and `klog.Warning` can be used.
 
-
 ## Resources
 
 - Some commands needs resources files, in the project uses the `Go 1.17` `go:embed` functionality to store the resources files.
-- Each command package contains its own resources in the scenario package. The scenario package contains one go file which provides the `go:embed` `embed.FS` files. 
+- Each command package contains its own resources in the scenario package. The scenario package contains one go file which provides the `go:embed` `embed.FS` files.
 
 ## Client
 
 - The [main](cmd/clusteradm.go) provides a cmdutil.Factory which can be leveraged to get different clients and also the *rest.Config. The factory can be passed to the cobra.Command and then save in the Options.
 
 ```Go
-	kubeClient, err := o.factory.KubernetesClientSet()
+kubeClient, err := o.factory.KubernetesClientSet()
 ```
 
 ```Go

cmd/clusteradm/clusteradm.go

@@ -69,6 +69,7 @@ func main() {
 
 	clusteradmFlags := genericclioptionsclusteradm.NewClusteradmFlags(f)
 	clusteradmFlags.AddFlags(flags)
+	clusteradmFlags.SetContext(kubeConfigFlags.Context)
 
 	// From this point and forward we get warnings on flags that contain "_" separators
 

go.mod

@@ -24,7 +24,7 @@ require (
 	k8s.io/component-base v0.23.5
 	k8s.io/klog/v2 v2.30.0
 	k8s.io/kubectl v0.23.5
-	open-cluster-management.io/api v0.7.1-0.20220630123726-101917f3a51a
+	open-cluster-management.io/api v0.8.0
 	open-cluster-management.io/cluster-proxy v0.1.2
 	open-cluster-management.io/managed-serviceaccount v0.2.1-0.20220427065210-de6a7b7b5be8
 	sigs.k8s.io/apiserver-network-proxy v0.0.30

go.sum

@@ -1802,10 +1802,8 @@ open-cluster-management.io/addon-framework v0.1.1-0.20211223101009-d6b1a7adae93/
 open-cluster-management.io/addon-framework v0.2.1-0.20220317063747-100a0230a883/go.mod h1:8QG1fHwPCEdyRrzY2Jji+qhMmJl+/HzTpuSDVmeG+7s=
 open-cluster-management.io/api v0.5.0/go.mod h1:9qiA5h/8kvPQnJEOlAPHVjRO9a1jCmDhGzvgMBvXEaE=
 open-cluster-management.io/api v0.5.1-0.20220112073018-2d280a97a052/go.mod h1:0IUTh8J+p4pv1THh1r9oO0luX9Z1FLDEAmvzW09qC0o=
-open-cluster-management.io/api v0.7.0 h1:Xt1tRCwt+wrhtCOEQ6g+7sFvIkMjffWnn5PSUSoKJcc=
-open-cluster-management.io/api v0.7.0/go.mod h1:Wg7YOcVNxsNDj2G8ViWTD/utCfb9cZc9MpNb4fKlXSs=
-open-cluster-management.io/api v0.7.1-0.20220630123726-101917f3a51a h1:FzGON866W5oidZEQwUoBaZZqWfcePIJSDTU5fsKPUVU=
-open-cluster-management.io/api v0.7.1-0.20220630123726-101917f3a51a/go.mod h1:+OEARSAl2jIhuLItUcS30UgLA3khmA9ihygLVxzEn+U=
+open-cluster-management.io/api v0.8.0 h1:hQLNyvvdx0G0iNxq80RWp93epNsUtsqJdLmGbXiYG5o=
+open-cluster-management.io/api v0.8.0/go.mod h1:+OEARSAl2jIhuLItUcS30UgLA3khmA9ihygLVxzEn+U=
 open-cluster-management.io/cluster-proxy v0.1.2 h1:0WYhPEZT6Wlt0dyE35GCC7zcqPo2poaALzdmVbQp9Dg=
 open-cluster-management.io/cluster-proxy v0.1.2/go.mod h1:f4HVfparQqOJsPrh4fTA4uyWx5KJ7MG2AcuSRypedws=
 open-cluster-management.io/managed-serviceaccount v0.2.1-0.20220427065210-de6a7b7b5be8 h1:foP5RkSec9DkUA8sJ5FLna5We8VxJyu0179id5zNXgA=

pkg/cmd/init/exec.go

@@ -6,6 +6,8 @@ import (
 	"os"
 	"time"
 
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"open-cluster-management.io/clusteradm/pkg/cmd/init/preflight"
 	"open-cluster-management.io/clusteradm/pkg/cmd/init/scenario"
 	"open-cluster-management.io/clusteradm/pkg/helpers"
 	"open-cluster-management.io/clusteradm/pkg/helpers/apply"
@@ -51,6 +53,28 @@ func (o *Options) validate() error {
 	if o.force {
 		return nil
 	}
+	// preflight check
+	f := o.ClusteradmFlags.KubectlFactory
+	kubeClient, _, _, err := helpers.GetClients(f)
+	if err != nil {
+		return err
+	}
+	if err := preflight.RunChecks(
+		[]preflight.Checker{
+			preflight.HubApiServerCheck{
+				ClusterCtx: o.ClusteradmFlags.Context,
+				ConfigPath: "", // TODO(@Promacanthus)： user custom kubeconfig path from command line arguments.
+			},
+			preflight.ClusterInfoCheck{
+				Namespace:    metav1.NamespacePublic,
+				ResourceName: preflight.BootstrapConfigMap,
+				ClusterCtx:   o.ClusteradmFlags.Context,
+				ConfigPath:   "", // TODO(@Promacanthus)： user custom kubeconfig path from command line arguments.
+				Client:       kubeClient,
+			},
+		}, os.Stderr); err != nil {
+		return err
+	}
 	restConfig, err := o.ClusteradmFlags.KubectlFactory.ToRESTConfig()
 	if err != nil {
 		return err

pkg/cmd/init/preflight/checks.go

@@ -0,0 +1,183 @@
+// Copyright Contributors to the Open Cluster Management project
+package preflight
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"net"
+	"net/url"
+
+	"github.com/pkg/errors"
+	corev1 "k8s.io/api/core/v1"
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/tools/clientcmd"
+	"k8s.io/client-go/tools/clientcmd/api"
+	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
+)
+
+var BootstrapConfigMap = "cluster-info"
+
+type Error struct {
+	Msg string
+}
+
+func (e Error) Error() string {
+	return fmt.Sprintf("[preflight] Some fatal errors occurred:\n%s", e.Msg)
+}
+
+func (e *Error) Preflight() bool {
+	return true
+}
+
+// Checker validates the state of the cluster to ensure
+// clusteradm will be successfully as often as possible.
+type Checker interface {
+	Check() (warnings, errorList []error)
+	Name() string
+}
+
+type HubApiServerCheck struct {
+	ClusterCtx string // current-context in kubeconfig
+	ConfigPath string // kubeconfig file path
+}
+
+func (c HubApiServerCheck) Check() (warnings []error, errorList []error) {
+	cluster, err := loadCurrentCluster(c.ClusterCtx, c.ConfigPath)
+	if err != nil {
+		return nil, []error{err}
+	}
+	u, err := url.Parse(cluster.Server)
+	if err != nil {
+		return nil, []error{err}
+	}
+	host, _, err := net.SplitHostPort(u.Host)
+	if err != nil {
+		return nil, []error{err}
+	}
+	if net.ParseIP(host) == nil {
+		return []error{errors.New("Hub Api Server is a domain name, maybe you should set HostAlias in klusterlet")}, nil
+	}
+	return nil, nil
+}
+
+func (c HubApiServerCheck) Name() string {
+	return "HubApiServer check"
+}
+
+// ClusterInfoCheck checks whether the target kubernetes resource exist in the cluster.
+type ClusterInfoCheck struct {
+	Namespace    string
+	ResourceName string
+	ClusterCtx   string // current-context in kubeconfig
+	ConfigPath   string // kubeconfig file path
+	Client       kubernetes.Interface
+}
+
+func (c ClusterInfoCheck) Check() (warnings []error, errorList []error) {
+	cm, err := c.Client.CoreV1().ConfigMaps(c.Namespace).Get(context.Background(), c.ResourceName, metav1.GetOptions{})
+	if err != nil {
+		if apierrors.IsNotFound(err) {
+			resourceNotFound := errors.New("no ConfigMap named cluster-info in the kube-public namespace, clusteradm will creates it")
+			cluster, err := loadCurrentCluster(c.ClusterCtx, c.ConfigPath)
+			if err != nil {
+				return []error{resourceNotFound}, []error{err}
+			}
+			if err := createClusterInfo(c.Client, cluster); err != nil {
+				return []error{resourceNotFound}, []error{err}
+			}
+			return []error{resourceNotFound}, nil
+		}
+		return nil, []error{err}
+	}
+	if len(cm.Data["kubeconfig"]) == 0 {
+		return nil, []error{errors.New("empty kubeconfig data in cluster-info")}
+	}
+	return nil, nil
+}
+
+func (c ClusterInfoCheck) Name() string {
+	return "cluster-info check"
+}
+
+// loadCurrentCluster will load kubeconfig from file and return the current cluster.
+// The default file path is ~/.kube/config.
+func loadCurrentCluster(context string, kubeConfigFilePath string) (*api.Cluster, error) {
+	var (
+		currentConfig *clientcmdapi.Config
+		err           error
+	)
+
+	if len(kubeConfigFilePath) == 0 {
+		currentConfig, err = clientcmd.NewDefaultClientConfigLoadingRules().Load()
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		currentConfig, err = clientcmd.LoadFromFile(kubeConfigFilePath)
+		if err != nil {
+			return nil, errors.Wrapf(err, "failed to load kubeconfig file %s that already exists on disk", kubeConfigFilePath)
+		}
+	}
+	// load kubeconfig from file
+	// get the hub cluster context
+	if len(context) == 0 {
+		// use the current context from the kubeconfig
+		context = currentConfig.CurrentContext
+	}
+	currentCtx, exists := currentConfig.Contexts[context]
+	if !exists {
+		return nil, errors.Errorf("failed to find the given Current Context in Contexts of the kubeconfig file %s", kubeConfigFilePath)
+	}
+	currentCluster, exists := currentConfig.Clusters[currentCtx.Cluster]
+	if !exists {
+		return nil, errors.Errorf("failed to find the given CurrentContext Cluster in Clusters of the kubeconfig file %s", kubeConfigFilePath)
+	}
+	return currentCluster, nil
+}
+
+// createClusterInfo will create a ConfigMap named cluster-info in the kube-public namespace.
+func createClusterInfo(client kubernetes.Interface, cluster *clientcmdapi.Cluster) error {
+	kubeconfig := &clientcmdapi.Config{Clusters: map[string]*clientcmdapi.Cluster{"": cluster}}
+	if err := clientcmdapi.FlattenConfig(kubeconfig); err != nil {
+		return err
+	}
+	kubeconfigBytes, err := clientcmd.Write(*kubeconfig)
+	if err != nil {
+		return err
+	}
+	clusterInfo := &corev1.ConfigMap{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      BootstrapConfigMap,
+			Namespace: metav1.NamespacePublic,
+		},
+		Immutable: BoolPointer(true),
+		Data: map[string]string{
+			"kubeconfig": string(kubeconfigBytes),
+		},
+	}
+	return CreateOrUpdateConfigMap(client, clusterInfo)
+}
+
+// RunChecks runs each check, display it's warning/errors,
+// and once all are processed will exist if any errors occured.
+func RunChecks(checks []Checker, ww io.Writer) error {
+	var errsBuffer bytes.Buffer
+	for _, check := range checks {
+		name := check.Name()
+		warnings, errs := check.Check()
+		for _, warning := range warnings {
+			_, _ = io.WriteString(ww, fmt.Sprintf("\t[WARNING %s]: %v\n", name, warning))
+		}
+		for _, err := range errs {
+			_, _ = errsBuffer.WriteString(fmt.Sprintf("\t[ERROR %s]: %v\n", name, err.Error()))
+		}
+	}
+	if errsBuffer.Len() > 0 {
+		return &Error{Msg: errsBuffer.String()}
+	}
+	return nil
+}