Activity indicator for init command (#207)

* first version of spinner

- implemented class with basic method
- covered with dummy test
- integrated with init command

* Style and license remarks

* fixed review remarks

* fixed typo + integration of spinner with terminate command

* integration of spinner with create command

cli/internal/cmd/create.go

@@ -114,7 +114,10 @@ func create(cmd *cobra.Command, creator cloudCreator, fileHandler file.Handler)
 		}
 	}
 
+	spinner := newSpinner(cmd, "Loading ", true)
+	spinner.Start()
 	state, err := creator.Create(cmd.Context(), provider, config, flags.name, instanceType, flags.controllerCount, flags.workerCount)
+	spinner.Stop()
 	if err != nil {
 		return err
 	}

cli/internal/cmd/init.go

@@ -124,7 +124,8 @@ func initialize(cmd *cobra.Command, newDialer func(validator *cloudcmd.Validator
 		return fmt.Errorf("parsing or generating master secret from file %s: %w", flags.masterSecretPath, err)
 	}
 
-	cmd.Println("Initializing cluster ...")
+	spinner := newSpinner(cmd, "Initializing cluster ", true)
+	spinner.Start()
 	req := &initproto.InitRequest{
 		MasterSecret:           masterSecret.Key,
 		Salt:                   masterSecret.Salt,
@@ -141,6 +142,7 @@ func initialize(cmd *cobra.Command, newDialer func(validator *cloudcmd.Validator
 		ConformanceMode:        flags.conformance,
 	}
 	resp, err := initCall(cmd.Context(), newDialer(validator), flags.endpoint, req)
+	spinner.Stop()
 	if err != nil {
 		return err
 	}

cli/internal/cmd/spinner.go

@@ -0,0 +1,73 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+package cmd
+
+import (
+	"fmt"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/spf13/cobra"
+)
+
+var (
+	spinnerStates = []string{"⣾", "⣽", "⣻", "⢿", "⡿", "⣟", "⣯", "⣷"}
+	dotsStates    = []string{".", "..", "..."}
+)
+
+type spinner struct {
+	out      *cobra.Command
+	text     string
+	showDots bool
+	delay    time.Duration
+	wg       *sync.WaitGroup
+	stop     int32
+}
+
+func newSpinner(c *cobra.Command, text string, showDots bool) *spinner {
+	return &spinner{
+		out:      c,
+		text:     text,
+		showDots: showDots,
+		wg:       &sync.WaitGroup{},
+		delay:    100 * time.Millisecond,
+		stop:     0,
+	}
+}
+
+func (s *spinner) Start() {
+	s.wg.Add(1)
+	go func() {
+		defer s.wg.Done()
+
+		for i := 0; ; i = (i + 1) % len(spinnerStates) {
+			if atomic.LoadInt32(&s.stop) != 0 {
+				break
+			}
+			dotsState := ""
+			if s.showDots {
+				dotsState = dotsStates[i%len(dotsStates)]
+			}
+			state := fmt.Sprintf("\r%s %s%s", spinnerStates[i], s.text, dotsState)
+			s.out.Print(state)
+			time.Sleep(s.delay)
+		}
+
+		dotsState := ""
+		if s.showDots {
+			dotsState = dotsStates[len(dotsStates)-1]
+		}
+		finalState := fmt.Sprintf("\r%s%s  ", s.text, dotsState)
+		s.out.Println(finalState)
+	}()
+}
+
+func (s *spinner) Stop() {
+	atomic.StoreInt32(&s.stop, 1)
+	s.wg.Wait()
+}

cli/internal/cmd/spinner_test.go

@@ -0,0 +1,91 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+package cmd
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+const (
+	baseWait = 1
+	baseText = "Loading"
+)
+
+func TestSpinnerInitialState(t *testing.T) {
+	cmd := NewInitCmd()
+	var out bytes.Buffer
+	cmd.SetOut(&out)
+	var errOut bytes.Buffer
+	cmd.SetErr(&errOut)
+
+	s := newSpinner(cmd, baseText, true)
+	s.Start()
+	time.Sleep(baseWait * time.Second)
+	s.Stop()
+	require.True(t, out.Len() > 0)
+	require.True(t, errOut.Len() == 0)
+
+	outStr := out.String()
+	require.True(t, strings.HasPrefix(outStr, generateAllStatesAsString(baseText, true)))
+}
+
+func TestSpinnerFinalState(t *testing.T) {
+	cmd := NewInitCmd()
+	var out bytes.Buffer
+	cmd.SetOut(&out)
+	var errOut bytes.Buffer
+	cmd.SetErr(&errOut)
+
+	s := newSpinner(cmd, baseText, true)
+	s.Start()
+	time.Sleep(baseWait * time.Second)
+	s.Stop()
+	require.True(t, out.Len() > 0)
+	require.True(t, errOut.Len() == 0)
+
+	outStr := out.String()
+	require.True(t, strings.HasSuffix(outStr, baseText+"...  \n"))
+}
+
+func TestSpinnerDisabledShowDotsFlag(t *testing.T) {
+	cmd := NewInitCmd()
+	var out bytes.Buffer
+	cmd.SetOut(&out)
+	var errOut bytes.Buffer
+	cmd.SetErr(&errOut)
+
+	s := newSpinner(cmd, baseText, false)
+	s.Start()
+	time.Sleep(baseWait * time.Second)
+	s.Stop()
+	require.True(t, out.Len() > 0)
+	require.True(t, errOut.Len() == 0)
+
+	outStr := out.String()
+	require.True(t, strings.HasPrefix(outStr, generateAllStatesAsString(baseText, false)))
+	require.True(t, strings.HasSuffix(outStr, baseText+"  \n"))
+}
+
+func generateAllStatesAsString(text string, showDots bool) string {
+	var builder strings.Builder
+
+	for i := 0; i < len(spinnerStates); i++ {
+		dotsState := ""
+		if showDots {
+			dotsState = dotsStates[i%len(dotsStates)]
+		}
+		builder.WriteString(fmt.Sprintf("\r%s %s%s", spinnerStates[i], text, dotsState))
+	}
+
+	return builder.String()
+}

cli/internal/cmd/terminate.go

@@ -47,9 +47,11 @@ func terminate(cmd *cobra.Command, terminator cloudTerminator, fileHandler file.
 		return fmt.Errorf("reading Constellation state: %w", err)
 	}
 
-	cmd.Println("Terminating ...")
+	spinner := newSpinner(cmd, "Terminating ", true)
-
+	spinner.Start()
-	if err := terminator.Terminate(cmd.Context(), stat); err != nil {
+	err := terminator.Terminate(cmd.Context(), stat)
+	spinner.Stop()
+	if err != nil {
 		return fmt.Errorf("terminating Constellation cluster: %w", err)
 	}