feat(cli): Implement --watch flag

go.mod

@@ -15,6 +15,7 @@ require (
 	github.com/imdario/mergo v0.3.12
 	github.com/jedib0t/go-pretty/v6 v6.3.1
 	github.com/kr/text v0.2.0
+	github.com/liggitt/tabwriter v0.0.0-20181228230101-89fcab3d43de
 	github.com/mitchellh/go-testing-interface v1.0.0
 	github.com/mitchellh/hashstructure/v2 v2.0.2
 	github.com/mitchellh/mapstructure v1.4.3
@@ -63,7 +64,6 @@ require (
 	github.com/josharian/intern v1.0.0 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
 	github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51 // indirect
-	github.com/liggitt/tabwriter v0.0.0-20181228230101-89fcab3d43de // indirect
 	github.com/mailru/easyjson v0.7.6 // indirect
 	github.com/mattn/go-colorable v0.1.9 // indirect
 	github.com/mattn/go-isatty v0.0.14 // indirect

pkg/cli/cmd/cmd_get.go

@@ -26,13 +26,34 @@ import (
 	"github.com/furiko-io/furiko/pkg/cli/streams"
 )
 
+type GetCommand struct {
+	streams *streams.Streams
+}
+
 func NewGetCommand(streams *streams.Streams) *cobra.Command {
+	c := &GetCommand{
+		streams: streams,
+	}
+
 	cmd := &cobra.Command{
 		Use:   "get",
 		Short: "Get one or more resources by name.",
 	}
 
-	// Add common flags
+	c.AddSubcommand(cmd, NewGetJobCommand(streams))
+	c.AddSubcommand(cmd, NewGetJobConfigCommand(streams))
+
+	return cmd
+}
+
+// AddSubcommand will register subcommand flags and add it to the parent command.
+func (c *GetCommand) AddSubcommand(cmd, subCommand *cobra.Command) {
+	c.RegisterFlags(subCommand)
+	cmd.AddCommand(subCommand)
+}
+
+// RegisterFlags will register flags for the given subcommand.
+func (c *GetCommand) RegisterFlags(cmd *cobra.Command) {
 	cmd.PersistentFlags().StringP("output", "o", string(printer.OutputFormatPretty),
 		fmt.Sprintf("Output format. One of: %v", strings.Join(printer.GetAllOutputFormatStrings(), "|")))
 
@@ -41,9 +62,4 @@ func NewGetCommand(streams *streams.Streams) *cobra.Command {
 	}); err != nil {
 		Fatal(err, DefaultErrorExitCode)
 	}
-
-	cmd.AddCommand(NewGetJobCommand(streams))
-	cmd.AddCommand(NewGetJobConfigCommand(streams))
-
-	return cmd
 }

pkg/cli/cmd/cmd_get_job.go

@@ -47,6 +47,8 @@ var (
 
 type GetJobCommand struct {
 	streams *streams.Streams
+
+	output printer.OutputFormat
 }
 
 func NewGetJobCommand(streams *streams.Streams) *cobra.Command {
@@ -62,23 +64,27 @@ func NewGetJobCommand(streams *streams.Streams) *cobra.Command {
 		PreRunE:           PrerunWithKubeconfig,
 		Args:              cobra.MinimumNArgs(1),
 		ValidArgsFunction: MakeCobraCompletionFunc((&CompletionHelper{}).ListJobs()),
-		RunE:              c.Run,
+		RunE: RunAllE(
+			c.Complete,
+			c.Run,
+		),
 	}
 
 	return cmd
 }
 
+func (c *GetJobCommand) Complete(cmd *cobra.Command, args []string) error {
+	c.output = GetOutputFormat(cmd)
+	return nil
+}
+
 func (c *GetJobCommand) Run(cmd *cobra.Command, args []string) error {
 	ctx := cmd.Context()
 	client := ctrlContext.Clientsets().Furiko().ExecutionV1alpha1()
 	namespace, err := GetNamespace(cmd)
 	if err != nil {
 		return err
 	}
-	output, err := GetOutputFormat(cmd)
-	if err != nil {
-		return err
-	}
 
 	if len(args) == 0 {
 		return errors.New("at least one name is required")
@@ -94,7 +100,7 @@ func (c *GetJobCommand) Run(cmd *cobra.Command, args []string) error {
 		jobs = append(jobs, job)
 	}
 
-	return c.PrintJobs(output, jobs)
+	return c.PrintJobs(c.output, jobs)
 }
 
 func (c *GetJobCommand) PrintJobs(output printer.OutputFormat, jobs []*execution.Job) error {

pkg/cli/cmd/cmd_get_jobconfig.go

@@ -50,6 +50,8 @@ var (
 
 type GetJobConfigCommand struct {
 	streams *streams.Streams
+
+	output printer.OutputFormat
 }
 
 func NewGetJobConfigCommand(streams *streams.Streams) *cobra.Command {
@@ -65,23 +67,27 @@ func NewGetJobConfigCommand(streams *streams.Streams) *cobra.Command {
 		PreRunE:           PrerunWithKubeconfig,
 		Args:              cobra.MinimumNArgs(1),
 		ValidArgsFunction: MakeCobraCompletionFunc((&CompletionHelper{}).ListJobConfigs()),
-		RunE:              c.Run,
+		RunE: RunAllE(
+			c.Complete,
+			c.Run,
+		),
 	}
 
 	return cmd
 }
 
+func (c *GetJobConfigCommand) Complete(cmd *cobra.Command, args []string) error {
+	c.output = GetOutputFormat(cmd)
+	return nil
+}
+
 func (c *GetJobConfigCommand) Run(cmd *cobra.Command, args []string) error {
 	ctx := cmd.Context()
 	client := ctrlContext.Clientsets().Furiko().ExecutionV1alpha1()
 	namespace, err := GetNamespace(cmd)
 	if err != nil {
 		return err
 	}
-	output, err := GetOutputFormat(cmd)
-	if err != nil {
-		return err
-	}
 
 	if len(args) == 0 {
 		return errors.New("at least one name is required")
@@ -96,7 +102,7 @@ func (c *GetJobConfigCommand) Run(cmd *cobra.Command, args []string) error {
 		jobConfigs = append(jobConfigs, jobConfig)
 	}
 
-	return c.PrintJobConfigs(ctx, cmd, output, jobConfigs)
+	return c.PrintJobConfigs(ctx, cmd, c.output, jobConfigs)
 }
 
 func (c *GetJobConfigCommand) PrintJobConfigs(

pkg/cli/cmd/cmd_list.go

@@ -26,26 +26,44 @@ import (
 	"github.com/furiko-io/furiko/pkg/cli/streams"
 )
 
+type ListCommand struct {
+	streams *streams.Streams
+}
+
 func NewListCommand(streams *streams.Streams) *cobra.Command {
+	c := &ListCommand{
+		streams: streams,
+	}
+
 	cmd := &cobra.Command{
 		Use:   "list",
 		Short: "List all resources by kind.",
 	}
 
-	// Add common flags
-	cmd.PersistentFlags().StringP("output", "o", string(printer.OutputFormatPretty),
+	c.AddSubcommand(cmd, NewListJobCommand(streams))
+	c.AddSubcommand(cmd, NewListJobConfigCommand(streams))
+
+	return cmd
+}
+
+// AddSubcommand will register subcommand flags and add it to the parent command.
+func (c *ListCommand) AddSubcommand(cmd, subCommand *cobra.Command) {
+	c.RegisterFlags(subCommand)
+	cmd.AddCommand(subCommand)
+}
+
+// RegisterFlags will register flags for the given subcommand.
+func (c *ListCommand) RegisterFlags(cmd *cobra.Command) {
+	cmd.Flags().StringP("output", "o", string(printer.OutputFormatPretty),
 		fmt.Sprintf("Output format. One of: %v", strings.Join(printer.GetAllOutputFormatStrings(), "|")))
-	cmd.PersistentFlags().Bool("no-headers", false,
+	cmd.Flags().Bool("no-headers", false,
 		"When using the default or custom-column output format, don't print headers (default print headers).")
+	cmd.Flags().BoolP("watch", "w", false,
+		"After listing the requested object(s), watch for changes and print them to the standard output.")
 
 	if err := RegisterFlagCompletions(cmd, []FlagCompletion{
 		{FlagName: "output", CompletionFunc: (&CompletionHelper{}).FromSlice(printer.AllOutputFormats)},
 	}); err != nil {
 		Fatal(err, DefaultErrorExitCode)
 	}
-
-	cmd.AddCommand(NewListJobCommand(streams))
-	cmd.AddCommand(NewListJobConfigCommand(streams))
-
-	return cmd
 }

pkg/cli/cmd/cmd_list_job.go

@@ -21,6 +21,7 @@ import (
 	"github.com/spf13/cobra"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/labels"
+	"k8s.io/apimachinery/pkg/runtime"
 
 	execution "github.com/furiko-io/furiko/apis/execution/v1alpha1"
 	"github.com/furiko-io/furiko/pkg/cli/formatter"
@@ -44,7 +45,9 @@ var (
 type ListJobCommand struct {
 	streams   *streams.Streams
 	jobConfig string
+	output    printer.OutputFormat
 	noHeaders bool
+	watch     bool
 }
 
 func NewListJobCommand(streams *streams.Streams) *cobra.Command {
@@ -59,7 +62,10 @@ func NewListJobCommand(streams *streams.Streams) *cobra.Command {
 		Example: ListJobExample,
 		PreRunE: PrerunWithKubeconfig,
 		Args:    cobra.ExactArgs(0),
-		RunE:    c.Run,
+		RunE: RunAllE(
+			c.Complete,
+			c.Run,
+		),
 	}
 
 	cmd.Flags().StringVar(&c.jobConfig, "for", "", "Return only jobs for the given job config.")
@@ -73,21 +79,20 @@ func NewListJobCommand(streams *streams.Streams) *cobra.Command {
 	return cmd
 }
 
+func (c *ListJobCommand) Complete(cmd *cobra.Command, args []string) error {
+	c.output = GetOutputFormat(cmd)
+	c.noHeaders = GetFlagBool(cmd, "no-headers")
+	c.watch = GetFlagBool(cmd, "watch")
+	return nil
+}
+
 func (c *ListJobCommand) Run(cmd *cobra.Command, args []string) error {
 	ctx := cmd.Context()
 	client := ctrlContext.Clientsets().Furiko().ExecutionV1alpha1()
 	namespace, err := GetNamespace(cmd)
 	if err != nil {
 		return err
 	}
-	output, err := GetOutputFormat(cmd)
-	if err != nil {
-		return err
-	}
-	c.noHeaders, err = GetNoHeaders(cmd)
-	if err != nil {
-		return err
-	}
 
 	// Filter to specific JobConfig.
 	var options metav1.ListOptions
@@ -108,18 +113,42 @@ func (c *ListJobCommand) Run(cmd *cobra.Command, args []string) error {
 		return errors.Wrapf(err, "cannot list jobs")
 	}
 
-	if len(jobList.Items) == 0 {
+	if len(jobList.Items) == 0 && !c.watch {
 		c.streams.Printf("No jobs found in %v namespace.\n", namespace)
 		return nil
 	}
 
-	return c.PrintJobs(output, jobList)
+	p := printer.NewTablePrinter(c.streams.Out)
+
+	if len(jobList.Items) > 0 {
+		if err := c.PrintJobs(p, jobList); err != nil {
+			return nil
+		}
+	}
+
+	if c.watch {
+		watchOptions := *options.DeepCopy()
+		watchOptions.ResourceVersion = jobList.ResourceVersion
+		watch, err := client.Jobs(namespace).Watch(ctx, watchOptions)
+		if err != nil {
+			return errors.Wrapf(err, "cannot watch jobs")
+		}
+
+		return WatchAndPrint(ctx, watch, func(obj runtime.Object) (bool, error) {
+			if job, ok := obj.(*execution.Job); ok {
+				return true, c.PrintJob(p, job)
+			}
+			return false, nil
+		})
+	}
+
+	return nil
 }
 
-func (c *ListJobCommand) PrintJobs(output printer.OutputFormat, jobList *execution.JobList) error {
+func (c *ListJobCommand) PrintJobs(p *printer.TablePrinter, jobList *execution.JobList) error {
 	// Handle pretty print as a special case.
-	if output == printer.OutputFormatPretty {
-		c.prettyPrint(jobList.Items)
+	if c.output == printer.OutputFormatPretty {
+		c.prettyPrint(p, jobList.Items)
 		return nil
 	}
 
@@ -130,7 +159,17 @@ func (c *ListJobCommand) PrintJobs(output printer.OutputFormat, jobList *executi
 		items = append(items, &job)
 	}
 
-	return printer.PrintObjects(execution.GVKJob, output, c.streams.Out, items)
+	return printer.PrintObjects(execution.GVKJob, c.output, c.streams.Out, items)
+}
+
+func (c *ListJobCommand) PrintJob(p *printer.TablePrinter, job *execution.Job) error {
+	// Handle pretty print as a special case.
+	if c.output == printer.OutputFormatPretty {
+		c.prettyPrint(p, []execution.Job{*job})
+		return nil
+	}
+
+	return printer.PrintObject(execution.GVKJob, c.output, c.streams.Out, job)
 }
 
 func (c *ListJobCommand) makeJobHeader() []string {
@@ -143,8 +182,7 @@ func (c *ListJobCommand) makeJobHeader() []string {
 	}
 }
 
-func (c *ListJobCommand) prettyPrint(jobs []execution.Job) {
-	p := printer.NewTablePrinter(c.streams.Out)
+func (c *ListJobCommand) prettyPrint(p *printer.TablePrinter, jobs []execution.Job) {
 	var headers []string
 	if !c.noHeaders {
 		headers = c.makeJobHeader()