feat: Add '--follow' flag for start/restart

This allows for following logs on re/starting instances.

Following logs prints everything from when the instance stopped.

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

Author: craciunoiuc

cmd/unikraft/integration/instance_test.go

@@ -146,6 +146,59 @@ func TestInstances(t *testing.T) {
 		r.Run(t, []string{"unikraft", "instance", "delete", "test-" + instName})
 	})
 
+	t.Run("start-follow", func(t *testing.T) {
+		r := runner(t, true)
+		instName := uniq()
+
+		// Create a stopped instance.
+		r.Run(t, []string{
+			"unikraft", "instance", "create",
+			"--output", "quiet",
+			"--set", "name=test-" + instName,
+			"--set", "metro=" + r.Config.MetroName,
+			"--set", "image=nginx:latest",
+			"--set", "autostart=false",
+			"--set", "resources.memory=128",
+			"--set", "resources.vcpus=1",
+		})
+
+		// Start it and follow logs; killed after 5 s is treated as success.
+		r.Run(t, []string{
+			"unikraft", "instance", "start",
+			"--follow",
+			"test-" + instName,
+		}, integ.WithTimeout(5*time.Second))
+
+		r.Run(t, []string{"unikraft", "instance", "delete", "test-" + instName})
+	})
+
+	t.Run("restart-follow", func(t *testing.T) {
+		r := runner(t, true)
+		instName := uniq()
+
+		// Create and start an instance.
+		r.Run(t, []string{
+			"unikraft", "instance", "create",
+			"--output", "quiet",
+			"--set", "name=test-" + instName,
+			"--set", "metro=" + r.Config.MetroName,
+			"--set", "image=nginx:latest",
+			"--set", "autostart=true",
+			"--set", "resources.memory=128",
+			"--set", "resources.vcpus=1",
+		})
+		r.Run(t, []string{"unikraft", "instance", "wait", "--until", "state==running", "--timeout", "30s", "test-" + instName})
+
+		// Restart it and follow logs; killed after 5 s is treated as success.
+		r.Run(t, []string{
+			"unikraft", "instance", "restart",
+			"--follow",
+			"test-" + instName,
+		}, integ.WithTimeout(5*time.Second))
+
+		r.Run(t, []string{"unikraft", "instance", "delete", "test-" + instName})
+	})
+
 	t.Run("edit", func(t *testing.T) {
 		r := runner(t, true)
 		instName := uniq()

cmd/unikraft/testdata/TestHelp/instances

@@ -57,10 +57,12 @@ require (
 	unikraft.com/x/joinerrgroup v0.0.0-20260304162956-523940cab1de
 	unikraft.com/x/kingkong v0.0.0-20260331102539-2c733927b46f
 	unikraft.com/x/kraftfile v0.0.0-20260501125416-502eb6c9c39d
-	unikraft.com/x/log v0.0.0-20260126171022-af62c17fcdf7
+	unikraft.com/x/log v0.0.0-20260527070319-f904d21cd6ea
 	unikraft.com/x/ptr v0.0.0-20260126094137-ab6e717e5679
 )
 
+require go.opentelemetry.io/otel/log v0.19.0 // indirect
+
 require (
 	charm.land/fang/v2 v2.0.1 // indirect
 	dario.cat/mergo v1.0.2 // indirect
@@ -92,7 +94,6 @@ require (
 	github.com/docker/go-connections v0.7.0 // indirect
 	github.com/felixge/httpsnoop v1.0.4 // indirect
 	github.com/fsnotify/fsnotify v1.9.0 // indirect
-	github.com/getsentry/sentry-go v0.41.0 // indirect
 	github.com/go-json-experiment/json v0.0.0-20250813024750-ebf49471dced // indirect
 	github.com/go-logr/logr v1.4.3 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect

go.mod

@@ -130,10 +130,6 @@ github.com/frankban/quicktest v1.14.6 h1:7Xjx+VpznH+oBnejlPUj8oUpdxnVs4f8XU8WnHk
 github.com/frankban/quicktest v1.14.6/go.mod h1:4ptaffx2x8+WTWXmUCuVU6aPUX1/Mz7zb5vbUoiM6w0=
 github.com/fsnotify/fsnotify v1.9.0 h1:2Ml+OJNzbYCTzsxtv8vKSFD9PbJjmhYF14k/jKC7S9k=
 github.com/fsnotify/fsnotify v1.9.0/go.mod h1:8jBTzvmWwFyi3Pb8djgCCO5IBqzKJ/Jwo8TRcHyHii0=
-github.com/getsentry/sentry-go v0.41.0 h1:q/dQZOlEIb4lhxQSjJhQqtRr3vwrJ6Ahe1C9zv+ryRo=
-github.com/getsentry/sentry-go v0.41.0/go.mod h1:eRXCoh3uvmjQLY6qu63BjUZnaBu5L5WhMV1RwYO8W5s=
-github.com/go-errors/errors v1.4.2 h1:J6MZopCL4uSllY1OfXM374weqZFFItUbrImctkmUxIA=
-github.com/go-errors/errors v1.4.2/go.mod h1:sIVyrIiJhuEF+Pj9Ebtd6P/rEYROXFi3BopGUQ5a5Og=
 github.com/go-json-experiment/json v0.0.0-20250813024750-ebf49471dced h1:Q311OHjMh/u5E2TITc++WlTP5We0xNseRMkHDyvhW7I=
 github.com/go-json-experiment/json v0.0.0-20250813024750-ebf49471dced/go.mod h1:TiCD2a1pcmjd7YnhGH0f/zKNcCD06B029pHhzV23c2M=
 github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
@@ -273,8 +269,6 @@ github.com/package-url/packageurl-go v0.1.1 h1:KTRE0bK3sKbFKAk3yy63DpeskU7Cvs/x/
 github.com/package-url/packageurl-go v0.1.1/go.mod h1:uQd4a7Rh3ZsVg5j0lNyAfyxIeGde9yrlhjF78GzeW0c=
 github.com/pelletier/go-toml/v2 v2.3.0 h1:k59bC/lIZREW0/iVaQR8nDHxVq8OVlIzYCOJf421CaM=
 github.com/pelletier/go-toml/v2 v2.3.0/go.mod h1:2gIqNv+qfxSVS7cM2xJQKtLSTLUE9V8t9Stt+h56mCY=
-github.com/pingcap/errors v0.11.4 h1:lFuQV/oaUMGcD2tqt+01ROSmJs75VG1ToEOkZIZ4nE4=
-github.com/pingcap/errors v0.11.4/go.mod h1:Oi8TUi2kEtXXLMJk9l1cGmz20kV3TaQ0usTwv5KuLY8=
 github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c h1:+mdjkGKdHQG3305AYmdv1U2eRNDiU2ErMBj1gwrq8eQ=
 github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c/go.mod h1:7rwL4CYBLnjLxUqIJNnCWiEdr3bn6IUYi15bNlnbCCU=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
@@ -394,6 +388,8 @@ go.opentelemetry.io/otel v1.43.0 h1:mYIM03dnh5zfN7HautFE4ieIig9amkNANT+xcVxAj9I=
 go.opentelemetry.io/otel v1.43.0/go.mod h1:JuG+u74mvjvcm8vj8pI5XiHy1zDeoCS2LB1spIq7Ay0=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.43.0 h1:88Y4s2C8oTui1LGM6bTWkw0ICGcOLCAI5l6zsD1j20k=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.43.0/go.mod h1:Vl1/iaggsuRlrHf/hfPJPvVag77kKyvrLeD10kpMl+A=
+go.opentelemetry.io/otel/log v0.19.0 h1:KUZs/GOsw79TBBMfDWsXS+KZ4g2Ckzksd1ymzsIEbo4=
+go.opentelemetry.io/otel/log v0.19.0/go.mod h1:5DQYeGmxVIr4n0/BcJvF4upsraHjg6vudJJpnkL6Ipk=
 go.opentelemetry.io/otel/metric v1.43.0 h1:d7638QeInOnuwOONPp4JAOGfbCEpYb+K6DVWvdxGzgM=
 go.opentelemetry.io/otel/metric v1.43.0/go.mod h1:RDnPtIxvqlgO8GRW18W6Z/4P462ldprJtfxHxyKd2PY=
 go.opentelemetry.io/otel/sdk v1.43.0 h1:pi5mE86i5rTeLXqoF/hhiBtUNcrAGHLKQdhg4h4V9Dg=
@@ -507,7 +503,7 @@ unikraft.com/x/kingkong v0.0.0-20260331102539-2c733927b46f h1:pT+qeeK2nWgSlRaIEK
 unikraft.com/x/kingkong v0.0.0-20260331102539-2c733927b46f/go.mod h1:x/sY2g/oA3GKDTZyOFC1xArmd6ZySwc4KZlp1MO8a2k=
 unikraft.com/x/kraftfile v0.0.0-20260501125416-502eb6c9c39d h1:x10/Kuf67r6UTYT0BuTbEkLdxHglWGY3eV+59WQFpWc=
 unikraft.com/x/kraftfile v0.0.0-20260501125416-502eb6c9c39d/go.mod h1:OYaIMOzV1IpbZCe2J3SuC5jvT4tAfR0XG9uOPPD+p50=
-unikraft.com/x/log v0.0.0-20260126171022-af62c17fcdf7 h1:kFOE7rmK33PiJ2GbWFd3v0WrE8DeAaQsPjrUQ+15CIU=
-unikraft.com/x/log v0.0.0-20260126171022-af62c17fcdf7/go.mod h1:f/+5628rnWTnRaRrCDD9mOMf7OV5QmkGIgARlTu4XGE=
+unikraft.com/x/log v0.0.0-20260527070319-f904d21cd6ea h1:nI+37MA1awnJXdM38jM5TjjYU8ATIZ79aICWcsl40Qc=
+unikraft.com/x/log v0.0.0-20260527070319-f904d21cd6ea/go.mod h1:Lq81MseYxHhX3SK7XSheX5QAZDOdKw1yhE84NTRZ5+g=
 unikraft.com/x/ptr v0.0.0-20260126094137-ab6e717e5679 h1:ohptI7loX492JCbbn6yk13hAxysZHyGIZWN8hTw3080=
 unikraft.com/x/ptr v0.0.0-20260126094137-ab6e717e5679/go.mod h1:une+KauhLNYkBFnT0R4bzVvD8bJ54xACjXMBPMnc5ig=

go.sum

@@ -1250,6 +1250,8 @@ 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
 }
 
@@ -1261,6 +1263,12 @@ 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",
+			},
+		},
 	}
 }
 
@@ -1275,6 +1283,19 @@ func (c *InstancesStartCmd) Run(ctx context.Context, stdio config.Stdio) error {
 		return err
 	}
 
+	var (
+		mux    *muxreader.Mux
+		cancel context.CancelFunc
+	)
+	if c.Follow {
+		mux, cancel, err = newInstanceLogMux(ctx, keys, new(0), true)
+		if err != nil {
+			return err
+		}
+		defer cancel()
+		defer mux.Close()
+	}
+
 	started, startErr := startInstances(ctx, g, keys)
 	opErr = errors.Join(opErr, startErr)
 	if len(started) == 0 {
@@ -1301,7 +1322,14 @@ 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 drainInstanceLogs(stdio, mux, true)
 }
 
 type InstancesStopCmd struct {
@@ -1381,6 +1409,8 @@ 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
 }
 
@@ -1398,6 +1428,12 @@ 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",
+			},
+		},
 	}
 }
 
@@ -1418,6 +1454,19 @@ func (c *InstancesRestartCmd) Run(ctx context.Context, stdio config.Stdio) error
 		return opErr
 	}
 
+	var (
+		mux    *muxreader.Mux
+		cancel context.CancelFunc
+	)
+	if c.Follow {
+		mux, cancel, err = newInstanceLogMux(ctx, stopped, new(0), true)
+		if err != nil {
+			return err
+		}
+		defer cancel()
+		defer mux.Close()
+	}
+
 	started, startErr := startInstances(ctx, g, stopped)
 	if len(started) == 0 {
 		if _, ok := startErr.(group.ErrRefNotFound); ok {
@@ -1448,7 +1497,14 @@ 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 drainInstanceLogs(stdio, mux, true)
 }
 
 type StopOpts struct {

internal/cmd/instances.go

@@ -128,40 +128,53 @@ func (c *RunCmd) Run(ctx context.Context, stdio config.Stdio, sandbox *resource.
 		keys = append(keys, instance.key)
 	}
 
-	return streamInstanceLogs(ctx, stdio, keys, 0, true)
+	return streamInstanceLogs(ctx, stdio, keys, nil, c.Follow)
 }
 
-func streamInstanceLogs(ctx context.Context, stdio config.Stdio, keys multimetro.Keys, tail int, follow bool) error {
+func newInstanceLogMux(ctx context.Context, keys multimetro.Keys, tail *int, follow bool) (*muxreader.Mux, context.CancelFunc, error) {
 	g, err := multimetro.NewClient(ctx)
 	if err != nil {
-		return err
+		return nil, nil, err
 	}
 
 	mux := muxreader.New()
-	defer mux.Close()
 
 	ctx, cancel := context.WithCancel(ctx)
-	defer cancel()
 
 	err = group.DoRefs(ctx, g, keys.Refs(), func(_ context.Context, c multimetro.MetroClient, refs group.Refs) (group.Refs, error) {
 		for _, ref := range refs {
-			key := multimetro.Key(ref)
-			r, err := logs.InstanceLogs(ctx, c).Reader(ref.NameOrUUID(), &tail, follow)
+			r, err := logs.InstanceLogs(ctx, c).Reader(ref.NameOrUUID(), tail, follow)
 			if err != nil {
 				return nil, err
 			}
-			mux.With(key.String(), r)
+			mux.With(multimetro.Key(ref).String(), r)
 		}
 		return refs, nil
 	})
 	if err != nil {
-		return err
+		cancel()
+		mux.Close()
+		return nil, nil, err
 	}
 	mux.Seal()
 
-	_, err = io.Copy(stdio.Stdout, mux)
+	return mux, cancel, nil
+}
+
+func drainInstanceLogs(stdio config.Stdio, mux *muxreader.Mux, follow bool) error {
+	_, err := io.Copy(stdio.Stdout, mux)
 	if follow && errors.Is(err, context.Canceled) {
 		return nil
 	}
 	return err
 }
+
+func streamInstanceLogs(ctx context.Context, stdio config.Stdio, keys multimetro.Keys, tail *int, follow bool) error {
+	mux, cancel, err := newInstanceLogMux(ctx, keys, tail, follow)
+	if err != nil {
+		return err
+	}
+	defer cancel()
+	defer mux.Close()
+	return drainInstanceLogs(stdio, mux, follow)
+}