feat(cmd): Add '--follow' flag for start/restart

This allows for following logs on re/starting instances.
This is not implemented for creation with autostart.

Signed-off-by: Cezar Craciunoiu <[email protected]>

Author: craciunoiuc

cmd/unikraft/instances_test.go

@@ -8,6 +8,7 @@ package main
 import (
 	"regexp"
 	"testing"
+	"time"
 )
 
 func instancesTests(t *testing.T, r *testRunner) {
@@ -169,6 +170,65 @@ func instancesTests(t *testing.T, r *testRunner) {
 			})
 	})
 
+	t.Run("start-follow", func(t *testing.T) {
+		r.
+			online().
+			withCleaners(instanceCleaners).
+			run(t, []command{
+				// Create a stopped instance
+				{args: []string{
+					unikraftCmd, "instance", "create",
+					"--output", "quiet",
+					"--set", "name=test-$UNIQ_INST",
+					"--set", "metro=" + metroName,
+					"--set", "image=nginx:latest",
+					"--set", "autostart=false",
+					"--set", "resources.memory=128",
+					"--set", "resources.vcpus=1",
+				}},
+				// Start it and follow logs for up to 5 seconds
+				{
+					args: []string{
+						unikraftCmd, "instance", "start",
+						"--follow",
+						"test-$UNIQ_INST",
+					},
+					timeout: 5 * time.Second,
+				},
+				{args: []string{unikraftCmd, "instance", "delete", "test-$UNIQ_INST"}},
+			})
+	})
+
+	t.Run("restart-follow", func(t *testing.T) {
+		r.
+			online().
+			withCleaners(instanceCleaners).
+			run(t, []command{
+				// Create and start an instance
+				{args: []string{
+					unikraftCmd, "instance", "create",
+					"--output", "quiet",
+					"--set", "name=test-$UNIQ_INST",
+					"--set", "metro=" + metroName,
+					"--set", "image=nginx:latest",
+					"--set", "autostart=true",
+					"--set", "resources.memory=128",
+					"--set", "resources.vcpus=1",
+				}},
+				{args: []string{unikraftCmd, "instance", "wait", "--until", "state==running", "--timeout", "30s", "test-$UNIQ_INST"}},
+				// Restart it and follow logs for up to 5 seconds
+				{
+					args: []string{
+						unikraftCmd, "instance", "restart",
+						"--follow",
+						"test-$UNIQ_INST",
+					},
+					timeout: 5 * time.Second,
+				},
+				{args: []string{unikraftCmd, "instance", "delete", "test-$UNIQ_INST"}},
+			})
+	})
+
 	t.Run("edit", func(t *testing.T) {
 		r.
 			online().

cmd/unikraft/main_test.go

@@ -58,6 +58,7 @@ type command struct {
 	args       []string
 	err        commandErr
 	captureEnv string
+	timeout    time.Duration
 }
 
 type commandErr int
@@ -201,12 +202,18 @@ func (b *testBuilder) run(t *testing.T, commands []command) {
 			Strs("args", args).
 			Msg("executing command")
 
+		cmdCtx := ctx
+		var cmdCancel context.CancelFunc
+		if command.timeout > 0 {
+			cmdCtx, cmdCancel = context.WithTimeout(ctx, command.timeout)
+		}
+
 		var cmd *exec.Cmd
 		if args[0] == unikraftCmd {
-			cmd = exec.CommandContext(ctx, r.unikraftPath, args[1:]...)
+			cmd = exec.CommandContext(cmdCtx, r.unikraftPath, args[1:]...)
 			cmd.Args[0] = r.unikraftPath
 		} else {
-			cmd = exec.CommandContext(ctx, args[0], args[1:]...)
+			cmd = exec.CommandContext(cmdCtx, args[0], args[1:]...)
 		}
 
 		var stdout, stderr bytes.Buffer
@@ -229,6 +236,15 @@ func (b *testBuilder) run(t *testing.T, commands []command) {
 		}
 
 		err := cmd.Run()
+		if cmdCancel != nil {
+			cmdCancel()
+		}
+		var killedErr *exec.ExitError
+		if command.timeout > 0 && errors.Is(cmdCtx.Err(), context.DeadlineExceeded) &&
+			errors.As(err, &killedErr) && killedErr.ExitCode() == -1 {
+			// The process was killed by the timeout: signal-terminated, exit code -1
+			err = nil
+		}
 		if command.captureEnv != "" {
 			value := strings.TrimSpace(stdout.String())
 			if value == "" {

cmd/unikraft/testdata/TestGolden/instances/help

@@ -1244,6 +1244,8 @@ func (cmd *InstancesLogsCmd) Run(ctx context.Context, stdio config.Stdio) error
 type InstancesStartCmd struct {
 	Targets []string `arg:"" name:"target" completion-predictor:"resource-key-instance" help:"Target instances to start."`
 
+	Follow bool `help:"Follow log output after starting."`
+
 	cmd.FormatOpts
 }
 
@@ -1255,6 +1257,12 @@ func (cmd InstancesStartCmd) Examples() []kingkong.Example {
 				"unikraft instance start demo-instance",
 			},
 		},
+		{
+			Description: "Start an instance and follow its logs",
+			Commands: []string{
+				"unikraft instance start demo-instance --follow",
+			},
+		},
 	}
 }
 
@@ -1295,7 +1303,14 @@ func (c *InstancesStartCmd) Run(ctx context.Context, stdio config.Stdio) error {
 	})
 
 	diffErr := cmd.Diff(ctx, stdio.Stdout, c.FormatOpts, Instance{}, before, updated)
-	return errors.Join(opErr, diffErr)
+	if err := errors.Join(opErr, diffErr); err != nil {
+		return err
+	}
+	if !c.Follow || len(started) == 0 {
+		return nil
+	}
+	fmt.Fprintln(stdio.Stdout)
+	return streamInstanceLogs(ctx, stdio, started, 0, true)
 }
 
 type InstancesStopCmd struct {
@@ -1371,6 +1386,8 @@ type InstancesRestartCmd struct {
 	Targets []string `arg:"" name:"target" completion-predictor:"resource-key-instance" help:"Target instances to restart."`
 	StopOpts
 
+	Follow bool `help:"Follow log output after restarting."`
+
 	cmd.FormatOpts
 }
 
@@ -1388,6 +1405,12 @@ func (cmd InstancesRestartCmd) Examples() []kingkong.Example {
 				"unikraft instance restart demo-instance --force",
 			},
 		},
+		{
+			Description: "Restart an instance and follow its logs",
+			Commands: []string{
+				"unikraft instance restart demo-instance --follow",
+			},
+		},
 	}
 }
 
@@ -1434,7 +1457,14 @@ func (c *InstancesRestartCmd) Run(ctx context.Context, stdio config.Stdio) error
 	})
 
 	diffErr := cmd.Diff(ctx, stdio.Stdout, c.FormatOpts, Instance{}, before, updated)
-	return errors.Join(opErr, diffErr)
+	if err := errors.Join(opErr, diffErr); err != nil {
+		return err
+	}
+	if !c.Follow || len(started) == 0 {
+		return nil
+	}
+	fmt.Fprintln(stdio.Stdout)
+	return streamInstanceLogs(ctx, stdio, started, 0, true)
 }
 
 type StopOpts struct {