Add dynamic completion suppport

This commit adds dynamic completion support for the following commands
and flags:

- `flux delete ...` command
- `flux export ...` command
- `flux get ...` command
- `flux reconcile ...` command
- `flux resume ...` command
- `flux suspend ...` command
- `--namespace` flag
- `--context` flag

Signed-off-by: Kazuki Suda <kazuki.suda@gmail.com>

cmd/flux/completion.go

@@ -17,7 +17,18 @@ limitations under the License.
 package main
 
 import (
+	"context"
+	"strings"
+
+	"github.com/fluxcd/flux2/internal/utils"
 	"github.com/spf13/cobra"
+	"k8s.io/apimachinery/pkg/api/meta"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/client-go/discovery"
+	memory "k8s.io/client-go/discovery/cached"
+	"k8s.io/client-go/dynamic"
+	"k8s.io/client-go/restmapper"
 )
 
 var completionCmd = &cobra.Command{
@@ -29,3 +40,77 @@ var completionCmd = &cobra.Command{
 func init() {
 	rootCmd.AddCommand(completionCmd)
 }
+
+func contextsCompletionFunc(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+	rawConfig, err := utils.ClientConfig(rootArgs.kubeconfig, rootArgs.kubecontext).RawConfig()
+	if err != nil {
+		return completionError(err)
+	}
+
+	var comps []string
+
+	for name := range rawConfig.Contexts {
+		if strings.HasPrefix(name, toComplete) {
+			comps = append(comps, name)
+		}
+	}
+
+	return comps, cobra.ShellCompDirectiveNoFileComp
+}
+
+func resourceNamesCompletionFunc(gvk schema.GroupVersionKind) func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+	return func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		ctx, cancel := context.WithTimeout(context.Background(), rootArgs.timeout)
+		defer cancel()
+
+		cfg, err := utils.KubeConfig(rootArgs.kubeconfig, rootArgs.kubecontext)
+		if err != nil {
+			return completionError(err)
+		}
+
+		dc, err := discovery.NewDiscoveryClientForConfig(cfg)
+		if err != nil {
+			return completionError(err)
+		}
+		mapper := restmapper.NewDeferredDiscoveryRESTMapper(memory.NewMemCacheClient(dc))
+
+		mapping, err := mapper.RESTMapping(gvk.GroupKind(), gvk.Version)
+		if err != nil {
+			return completionError(err)
+		}
+
+		client, err := dynamic.NewForConfig(cfg)
+		if err != nil {
+			return completionError(err)
+		}
+
+		var dr dynamic.ResourceInterface
+		if mapping.Scope.Name() == meta.RESTScopeNameNamespace {
+			dr = client.Resource(mapping.Resource).Namespace(rootArgs.namespace)
+		} else {
+			dr = client.Resource(mapping.Resource)
+		}
+
+		list, err := dr.List(ctx, metav1.ListOptions{})
+		if err != nil {
+			return completionError(err)
+		}
+
+		var comps []string
+
+		for _, item := range list.Items {
+			name := item.GetName()
+
+			if strings.HasPrefix(name, toComplete) {
+				comps = append(comps, name)
+			}
+		}
+
+		return comps, cobra.ShellCompDirectiveNoFileComp
+	}
+}
+
+func completionError(err error) ([]string, cobra.ShellCompDirective) {
+	cobra.CompError(err.Error())
+	return nil, cobra.ShellCompDirectiveError
+}

cmd/flux/delete_alert.go

@@ -28,6 +28,7 @@ var deleteAlertCmd = &cobra.Command{
 	Long:  "The delete alert command removes the given Alert from the cluster.",
 	Example: `  # Delete an Alert and the Kubernetes resources created by it
   flux delete alert main`,
+	ValidArgsFunction: resourceNamesCompletionFunc(notificationv1.GroupVersion.WithKind(notificationv1.AlertKind)),
 	RunE: deleteCommand{
 		apiType: alertType,
 		object:  universalAdapter{&notificationv1.Alert{}},

cmd/flux/delete_alertprovider.go

@@ -28,6 +28,7 @@ var deleteAlertProviderCmd = &cobra.Command{
 	Long:  "The delete alert-provider command removes the given Provider from the cluster.",
 	Example: `  # Delete a Provider and the Kubernetes resources created by it
   flux delete alert-provider slack`,
+	ValidArgsFunction: resourceNamesCompletionFunc(notificationv1.GroupVersion.WithKind(notificationv1.ProviderKind)),
 	RunE: deleteCommand{
 		apiType: alertProviderType,
 		object:  universalAdapter{&notificationv1.Provider{}},

cmd/flux/delete_helmrelease.go

@@ -29,6 +29,7 @@ var deleteHelmReleaseCmd = &cobra.Command{
 	Long:    "The delete helmrelease command removes the given HelmRelease from the cluster.",
 	Example: `  # Delete a Helm release and the Kubernetes resources created by it
   flux delete hr podinfo`,
+	ValidArgsFunction: resourceNamesCompletionFunc(helmv2.GroupVersion.WithKind(helmv2.HelmReleaseKind)),
 	RunE: deleteCommand{
 		apiType: helmReleaseType,
 		object:  universalAdapter{&helmv2.HelmRelease{}},

cmd/flux/delete_image_policy.go

@@ -28,6 +28,7 @@ var deleteImagePolicyCmd = &cobra.Command{
 	Long:  "The delete image policy command deletes the given ImagePolicy from the cluster.",
 	Example: `  # Delete an image policy
   flux delete image policy alpine3.x`,
+	ValidArgsFunction: resourceNamesCompletionFunc(imagev1.GroupVersion.WithKind(imagev1.ImagePolicyKind)),
 	RunE: deleteCommand{
 		apiType: imagePolicyType,
 		object:  universalAdapter{&imagev1.ImagePolicy{}},

cmd/flux/delete_image_repository.go

@@ -28,6 +28,7 @@ var deleteImageRepositoryCmd = &cobra.Command{
 	Long:  "The delete image repository command deletes the given ImageRepository from the cluster.",
 	Example: `  # Delete an image repository
   flux delete image repository alpine`,
+	ValidArgsFunction: resourceNamesCompletionFunc(imagev1.GroupVersion.WithKind(imagev1.ImageRepositoryKind)),
 	RunE: deleteCommand{
 		apiType: imageRepositoryType,
 		object:  universalAdapter{&imagev1.ImageRepository{}},

cmd/flux/delete_image_update.go

@@ -28,6 +28,7 @@ var deleteImageUpdateCmd = &cobra.Command{
 	Long:  "The delete image update command deletes the given ImageUpdateAutomation from the cluster.",
 	Example: `  # Delete an image update automation
   flux delete image update latest-images`,
+	ValidArgsFunction: resourceNamesCompletionFunc(autov1.GroupVersion.WithKind(autov1.ImageUpdateAutomationKind)),
 	RunE: deleteCommand{
 		apiType: imageUpdateAutomationType,
 		object:  universalAdapter{&autov1.ImageUpdateAutomation{}},

cmd/flux/delete_kustomization.go

@@ -29,6 +29,7 @@ var deleteKsCmd = &cobra.Command{
 	Long:    "The delete kustomization command deletes the given Kustomization from the cluster.",
 	Example: `  # Delete a kustomization and the Kubernetes resources created by it
   flux delete kustomization podinfo`,
+	ValidArgsFunction: resourceNamesCompletionFunc(kustomizev1.GroupVersion.WithKind(kustomizev1.KustomizationKind)),
 	RunE: deleteCommand{
 		apiType: kustomizationType,
 		object:  universalAdapter{&kustomizev1.Kustomization{}},

cmd/flux/delete_receiver.go

@@ -28,6 +28,7 @@ var deleteReceiverCmd = &cobra.Command{
 	Long:  "The delete receiver command removes the given Receiver from the cluster.",
 	Example: `  # Delete an Receiver and the Kubernetes resources created by it
   flux delete receiver main`,
+	ValidArgsFunction: resourceNamesCompletionFunc(notificationv1.GroupVersion.WithKind(notificationv1.ReceiverKind)),
 	RunE: deleteCommand{
 		apiType: receiverType,
 		object:  universalAdapter{&notificationv1.Receiver{}},

cmd/flux/delete_source_bucket.go

@@ -28,6 +28,7 @@ var deleteSourceBucketCmd = &cobra.Command{
 	Long:  "The delete source bucket command deletes the given Bucket from the cluster.",
 	Example: `  # Delete a Bucket source
   flux delete source bucket podinfo`,
+	ValidArgsFunction: resourceNamesCompletionFunc(sourcev1.GroupVersion.WithKind(sourcev1.BucketKind)),
 	RunE: deleteCommand{
 		apiType: bucketType,
 		object:  universalAdapter{&sourcev1.Bucket{}},

cmd/flux/delete_source_git.go

@@ -28,6 +28,7 @@ var deleteSourceGitCmd = &cobra.Command{
 	Long:  "The delete source git command deletes the given GitRepository from the cluster.",
 	Example: `  # Delete a Git repository
   flux delete source git podinfo`,
+	ValidArgsFunction: resourceNamesCompletionFunc(sourcev1.GroupVersion.WithKind(sourcev1.GitRepositoryKind)),
 	RunE: deleteCommand{
 		apiType: gitRepositoryType,
 		object:  universalAdapter{&sourcev1.GitRepository{}},

cmd/flux/delete_source_helm.go

@@ -28,6 +28,7 @@ var deleteSourceHelmCmd = &cobra.Command{
 	Long:  "The delete source helm command deletes the given HelmRepository from the cluster.",
 	Example: `  # Delete a Helm repository
   flux delete source helm podinfo`,
+	ValidArgsFunction: resourceNamesCompletionFunc(sourcev1.GroupVersion.WithKind(sourcev1.HelmRepositoryKind)),
 	RunE: deleteCommand{
 		apiType: helmRepositoryType,
 		object:  universalAdapter{&sourcev1.HelmRepository{}},

cmd/flux/export_alert.go

@@ -32,6 +32,7 @@ var exportAlertCmd = &cobra.Command{
 
   # Export a Alert
   flux export alert main > main.yaml`,
+	ValidArgsFunction: resourceNamesCompletionFunc(notificationv1.GroupVersion.WithKind(notificationv1.AlertKind)),
 	RunE: exportCommand{
 		object: alertAdapter{&notificationv1.Alert{}},
 		list:   alertListAdapter{&notificationv1.AlertList{}},

cmd/flux/export_alertprovider.go

@@ -32,6 +32,7 @@ var exportAlertProviderCmd = &cobra.Command{
 
   # Export a Provider
   flux export alert-provider slack > slack.yaml`,
+	ValidArgsFunction: resourceNamesCompletionFunc(notificationv1.GroupVersion.WithKind(notificationv1.ProviderKind)),
 	RunE: exportCommand{
 		object: alertProviderAdapter{&notificationv1.Provider{}},
 		list:   alertProviderListAdapter{&notificationv1.ProviderList{}},

cmd/flux/export_helmrelease.go

@@ -33,6 +33,7 @@ var exportHelmReleaseCmd = &cobra.Command{
 
   # Export a HelmRelease
   flux export hr my-app > app-release.yaml`,
+	ValidArgsFunction: resourceNamesCompletionFunc(helmv2.GroupVersion.WithKind(helmv2.HelmReleaseKind)),
 	RunE: exportCommand{
 		object: helmReleaseAdapter{&helmv2.HelmRelease{}},
 		list:   helmReleaseListAdapter{&helmv2.HelmReleaseList{}},

cmd/flux/export_image_policy.go

@@ -32,6 +32,7 @@ var exportImagePolicyCmd = &cobra.Command{
 
   # Export a specific policy
   flux export image policy alpine1x > alpine1x.yaml`,
+	ValidArgsFunction: resourceNamesCompletionFunc(imagev1.GroupVersion.WithKind(imagev1.ImagePolicyKind)),
 	RunE: exportCommand{
 		object: imagePolicyAdapter{&imagev1.ImagePolicy{}},
 		list:   imagePolicyListAdapter{&imagev1.ImagePolicyList{}},

cmd/flux/export_image_repository.go

@@ -32,6 +32,7 @@ var exportImageRepositoryCmd = &cobra.Command{
 
   # Export a specific ImageRepository resource
   flux export image repository alpine > alpine.yaml`,
+	ValidArgsFunction: resourceNamesCompletionFunc(imagev1.GroupVersion.WithKind(imagev1.ImageRepositoryKind)),
 	RunE: exportCommand{
 		object: imageRepositoryAdapter{&imagev1.ImageRepository{}},
 		list:   imageRepositoryListAdapter{&imagev1.ImageRepositoryList{}},

cmd/flux/export_image_update.go

@@ -32,6 +32,7 @@ var exportImageUpdateCmd = &cobra.Command{
 
   # Export a specific automation
   flux export image update latest-images > latest.yaml`,
+	ValidArgsFunction: resourceNamesCompletionFunc(autov1.GroupVersion.WithKind(autov1.ImageUpdateAutomationKind)),
 	RunE: exportCommand{
 		object: imageUpdateAutomationAdapter{&autov1.ImageUpdateAutomation{}},
 		list:   imageUpdateAutomationListAdapter{&autov1.ImageUpdateAutomationList{}},

cmd/flux/export_kustomization.go

@@ -33,6 +33,7 @@ var exportKsCmd = &cobra.Command{
 
   # Export a Kustomization
   flux export kustomization my-app > kustomization.yaml`,
+	ValidArgsFunction: resourceNamesCompletionFunc(kustomizev1.GroupVersion.WithKind(kustomizev1.KustomizationKind)),
 	RunE: exportCommand{
 		object: kustomizationAdapter{&kustomizev1.Kustomization{}},
 		list:   kustomizationListAdapter{&kustomizev1.KustomizationList{}},

cmd/flux/export_receiver.go

@@ -32,6 +32,7 @@ var exportReceiverCmd = &cobra.Command{
 
   # Export a Receiver
   flux export receiver main > main.yaml`,
+	ValidArgsFunction: resourceNamesCompletionFunc(notificationv1.GroupVersion.WithKind(notificationv1.ReceiverKind)),
 	RunE: exportCommand{
 		list:   receiverListAdapter{&notificationv1.ReceiverList{}},
 		object: receiverAdapter{&notificationv1.Receiver{}},