Add keybinding to cycle the log tail line count in the Logs tab

docs/keybindings/Keybindings_de.md

@@ -25,6 +25,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
   <kbd>a</kbd>: anbinden
   <kbd>m</kbd>: zeige Protokolle
   <kbd>E</kbd>: exec shell
+  <kbd>t</kbd>: cycle how many log lines are shown
   <kbd>c</kbd>: führe vordefinierten benutzerdefinierten Befehl aus
   <kbd>b</kbd>: view bulk commands
   <kbd>w</kbd>: open in browser (first port is http)
@@ -45,6 +46,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
   <kbd>S</kbd>: start
   <kbd>a</kbd>: anbinden
   <kbd>m</kbd>: zeige Protokolle
+  <kbd>t</kbd>: cycle how many log lines are shown
   <kbd>U</kbd>: up project
   <kbd>D</kbd>: down project
   <kbd>R</kbd>: zeige Neustartoptionen

docs/keybindings/Keybindings_en.md

@@ -25,6 +25,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
   <kbd>a</kbd>: attach
   <kbd>m</kbd>: view logs
   <kbd>E</kbd>: exec shell
+  <kbd>t</kbd>: cycle how many log lines are shown
   <kbd>c</kbd>: run predefined custom command
   <kbd>b</kbd>: view bulk commands
   <kbd>w</kbd>: open in browser (first port is http)
@@ -45,6 +46,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
   <kbd>S</kbd>: start
   <kbd>a</kbd>: attach
   <kbd>m</kbd>: view logs
+  <kbd>t</kbd>: cycle how many log lines are shown
   <kbd>U</kbd>: up project
   <kbd>D</kbd>: down project
   <kbd>R</kbd>: view restart options

docs/keybindings/Keybindings_es.md

@@ -25,6 +25,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
   <kbd>a</kbd>: attach
   <kbd>m</kbd>: ver logs
   <kbd>E</kbd>: ejecutar shell
+  <kbd>t</kbd>: cycle how many log lines are shown
   <kbd>c</kbd>: ejecutar comando personalizado
   <kbd>b</kbd>: ver comandos masivos
   <kbd>w</kbd>: abrir en navegador (first port is http)
@@ -45,6 +46,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
   <kbd>S</kbd>: iniciar
   <kbd>a</kbd>: attach
   <kbd>m</kbd>: ver logs
+  <kbd>t</kbd>: cycle how many log lines are shown
   <kbd>U</kbd>: levantar proyecto
   <kbd>D</kbd>: dar de baja el proyecto
   <kbd>R</kbd>: ver opciones de reinicio

docs/keybindings/Keybindings_fr.md

@@ -25,6 +25,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
   <kbd>a</kbd>: attacher
   <kbd>m</kbd>: voir les enregistrements
   <kbd>E</kbd>: exécuter le shell
+  <kbd>t</kbd>: cycle how many log lines are shown
   <kbd>c</kbd>: exécuter une commande prédéfinie
   <kbd>b</kbd>: voir les commandes groupées
   <kbd>w</kbd>: ouvrir dans le navigateur (le premier port est http)
@@ -45,6 +46,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
   <kbd>S</kbd>: démarrer
   <kbd>a</kbd>: attacher
   <kbd>m</kbd>: voir les enregistrements
+  <kbd>t</kbd>: cycle how many log lines are shown
   <kbd>U</kbd>: up project
   <kbd>D</kbd>: down project
   <kbd>R</kbd>: voir les options de redémarrage

docs/keybindings/Keybindings_nl.md

@@ -25,6 +25,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
   <kbd>a</kbd>: verbinden
   <kbd>m</kbd>: bekijk logs
   <kbd>E</kbd>: exec shell
+  <kbd>t</kbd>: cycle how many log lines are shown
   <kbd>c</kbd>: draai een vooraf bedacht aangepaste opdracht
   <kbd>b</kbd>: view bulk commands
   <kbd>w</kbd>: open in browser (first port is http)
@@ -45,6 +46,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
   <kbd>S</kbd>: start
   <kbd>a</kbd>: verbinden
   <kbd>m</kbd>: bekijk logs
+  <kbd>t</kbd>: cycle how many log lines are shown
   <kbd>U</kbd>: up project
   <kbd>D</kbd>: down project
   <kbd>R</kbd>: bekijk herstart opties

docs/keybindings/Keybindings_pl.md

@@ -25,6 +25,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
   <kbd>a</kbd>: przyczep
   <kbd>m</kbd>: pokaż logi
   <kbd>E</kbd>: exec shell
+  <kbd>t</kbd>: cycle how many log lines are shown
   <kbd>c</kbd>: wykonaj predefiniowaną własną komende
   <kbd>b</kbd>: view bulk commands
   <kbd>w</kbd>: open in browser (first port is http)
@@ -45,6 +46,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
   <kbd>S</kbd>: start
   <kbd>a</kbd>: przyczep
   <kbd>m</kbd>: pokaż logi
+  <kbd>t</kbd>: cycle how many log lines are shown
   <kbd>U</kbd>: up project
   <kbd>D</kbd>: down project
   <kbd>R</kbd>: pokaż opcje restartu

docs/keybindings/Keybindings_pt.md

@@ -25,6 +25,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
   <kbd>a</kbd>: anexar
   <kbd>m</kbd>: ver logs
   <kbd>E</kbd>: executar shell
+  <kbd>t</kbd>: cycle how many log lines are shown
   <kbd>c</kbd>: executar comando personalizado predefinido
   <kbd>b</kbd>: ver comandos em massa
   <kbd>w</kbd>: abrir no navegador (primeira porta é http)
@@ -45,6 +46,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
   <kbd>S</kbd>: iniciar
   <kbd>a</kbd>: anexar
   <kbd>m</kbd>: ver logs
+  <kbd>t</kbd>: cycle how many log lines are shown
   <kbd>U</kbd>: subir projeto
   <kbd>D</kbd>: derrubar projeto
   <kbd>R</kbd>: ver opções de reinício

docs/keybindings/Keybindings_tr.md

@@ -25,6 +25,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
   <kbd>a</kbd>: bağlan/iliştir
   <kbd>m</kbd>: kayıt defterini görüntüle
   <kbd>E</kbd>: exec shell
+  <kbd>t</kbd>: cycle how many log lines are shown
   <kbd>c</kbd>: önceden tanımlanmış özel komutu çalıştır
   <kbd>b</kbd>: view bulk commands
   <kbd>w</kbd>: open in browser (first port is http)
@@ -45,6 +46,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
   <kbd>S</kbd>: start
   <kbd>a</kbd>: bağlan/iliştir
   <kbd>m</kbd>: kayıt defterini görüntüle
+  <kbd>t</kbd>: cycle how many log lines are shown
   <kbd>U</kbd>: up project
   <kbd>D</kbd>: down project
   <kbd>R</kbd>: yeniden başlatma seçeneklerini görüntüle

docs/keybindings/Keybindings_zh.md

@@ -25,6 +25,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
   <kbd>a</kbd>: attach
   <kbd>m</kbd>: 查看日志
   <kbd>E</kbd>: 执行shell
+  <kbd>t</kbd>: cycle how many log lines are shown
   <kbd>c</kbd>: 运行预定义的自定义命令
   <kbd>b</kbd>: 查看批量命令
   <kbd>w</kbd>: 在浏览器中打开(第一个端口为http)
@@ -45,6 +46,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
   <kbd>S</kbd>: 启动项目
   <kbd>a</kbd>: attach
   <kbd>m</kbd>: 查看日志
+  <kbd>t</kbd>: cycle how many log lines are shown
   <kbd>U</kbd>: 创建并启动容器
   <kbd>D</kbd>: 停止并移除容器
   <kbd>R</kbd>: 查看重启选项

pkg/gui/container_logs.go

@@ -6,16 +6,88 @@ import (
 	"io"
 	"os"
 	"os/signal"
+	"strconv"
+	"strings"
 	"time"
 
 	"github.com/docker/docker/api/types/container"
 	"github.com/docker/docker/pkg/stdcopy"
 	"github.com/fatih/color"
+	"github.com/jesseduffield/gocui"
 	"github.com/jesseduffield/lazydocker/pkg/commands"
 	"github.com/jesseduffield/lazydocker/pkg/tasks"
 	"github.com/jesseduffield/lazydocker/pkg/utils"
 )
 
+// containerLogsTailPresets are the values we cycle through when the user asks to
+// change how many lines of logs are displayed. An empty string means 'show all logs'.
+var containerLogsTailPresets = []string{"", "50", "100", "200", "500"}
+
+func containerLogsTailLabel(tail string) string {
+	if tail == "" {
+		return "all"
+	}
+
+	return tail
+}
+
+// cycleContainerLogsTail moves to the next tail preset (wrapping back to the start)
+// and forces the logs tab to re-render with the new value.
+func (gui *Gui) cycleContainerLogsTail(g *gocui.Gui, v *gocui.View) error {
+	currentIdx := 0
+	for i, preset := range containerLogsTailPresets {
+		if preset == gui.State.ContainerLogsTail {
+			currentIdx = i
+			break
+		}
+	}
+
+	gui.State.ContainerLogsTail = containerLogsTailPresets[(currentIdx+1)%len(containerLogsTailPresets)]
+
+	if v != nil && v.Name() == "services" {
+		return gui.Panels.Services.HandleSelect()
+	}
+
+	return gui.Panels.Containers.HandleSelect()
+}
+
+// tailLimitingWriter wraps a writer and re-renders it on every line so that it only
+// ever displays the last maxLines lines, keeping a true sliding window rather than
+// just applying `--tail` to the initial snapshot and then growing forever as new
+// lines are followed in.
+type tailLimitingWriter struct {
+	view     *gocui.View
+	maxLines int
+	lines    []string
+	partial  string
+}
+
+func newTailLimitingWriter(view *gocui.View, maxLines int) *tailLimitingWriter {
+	return &tailLimitingWriter{view: view, maxLines: maxLines}
+}
+
+func (w *tailLimitingWriter) Write(p []byte) (int, error) {
+	w.partial += string(p)
+	split := strings.Split(w.partial, "\n")
+	w.partial = split[len(split)-1]
+	newLines := split[:len(split)-1]
+
+	if len(newLines) == 0 {
+		return len(p), nil
+	}
+
+	w.lines = append(w.lines, newLines...)
+	if excess := len(w.lines) - w.maxLines; excess > 0 {
+		w.lines = w.lines[excess:]
+	}
+
+	// SetContent clears and rewrites atomically, so the view never renders empty
+	// in between
+	w.view.SetContent(strings.Join(w.lines, "\n") + "\n")
+
+	return len(p), nil
+}
+
 func (gui *Gui) renderContainerLogsToMain(container *commands.Container) tasks.TaskFunc {
 	return gui.NewTickerTask(TickerTaskOpts{
 		Func: func(ctx context.Context, notifyStopped chan struct{}) {
@@ -36,8 +108,17 @@ func (gui *Gui) renderContainerLogsToMainAux(container *commands.Container, ctx
 	}()
 
 	mainView := gui.Views.Main
+	tail := gui.State.ContainerLogsTail
+	mainView.Subtitle = fmt.Sprintf("tail: %s (%s to cycle)", containerLogsTailLabel(tail), "t")
+
+	var writer io.Writer = mainView
+	if maxLines, err := strconv.Atoi(tail); err == nil && maxLines > 0 {
+		// keep re-truncating to the chosen number of lines as new ones stream in,
+		// instead of just limiting the initial snapshot and growing unbounded after that
+		writer = newTailLimitingWriter(mainView, maxLines)
+	}
 
-	if err := gui.writeContainerLogs(container, ctx, mainView); err != nil {
+	if err := gui.writeContainerLogs(container, ctx, writer); err != nil {
 		gui.Log.Error(err)
 	}
 
@@ -110,7 +191,7 @@ func (gui *Gui) writeContainerLogs(ctr *commands.Container, ctx context.Context,
 		ShowStderr: true,
 		Timestamps: gui.Config.UserConfig.Logs.Timestamps,
 		Since:      gui.Config.UserConfig.Logs.Since,
-		Tail:       gui.Config.UserConfig.Logs.Tail,
+		Tail:       gui.State.ContainerLogsTail,
 		Follow:     true,
 	})
 	if err != nil {

pkg/gui/containers_panel.go

@@ -68,7 +68,7 @@ func (gui *Gui) getContainersPanel() *panels.SideListPanel[*commands.Container]
 				// where a container restarts but the new logs don't get read.
 				// Note that this might be jarring if we have a lot of logs and the container
 				// restarts a lot, so let's keep an eye on it.
-				return "containers-" + container.ID + "-" + container.Container.State
+				return "containers-" + container.ID + "-" + container.Container.State + "-" + gui.State.ContainerLogsTail
 			},
 		},
 		ListPanel: panels.ListPanel[*commands.Container]{

pkg/gui/gui.go

@@ -82,6 +82,12 @@ type guiState struct {
 	// if true, we show containers with an 'exited' status in the containers panel
 	ShowExitedContainers bool
 
+	// the number of lines to pass as `--tail` when reading a container's logs. Empty
+	// string means we show all of the logs. This starts out as whatever is configured
+	// in the user's config, and can be cycled through ContainerLogsTailPresets via a
+	// keybinding.
+	ContainerLogsTail string
+
 	ScreenMode WindowMaximisation
 
 	// Maintains the state of manual filtering i.e. typing in a substring
@@ -136,6 +142,7 @@ func NewGui(log *logrus.Entry, dockerCommand *commands.DockerCommand, oSCommand
 		ViewStack: []string{},
 
 		ShowExitedContainers: true,
+		ContainerLogsTail:    config.UserConfig.Logs.Tail,
 		ScreenMode:           getScreenMode(config),
 	}
 

pkg/gui/keybindings.go

@@ -241,6 +241,13 @@ func (gui *Gui) GetInitialKeybindings() []*Binding {
 			Handler:     gui.handleContainersExecShell,
 			Description: gui.Tr.ExecShell,
 		},
+		{
+			ViewName:    "containers",
+			Key:         't',
+			Modifier:    gocui.ModNone,
+			Handler:     gui.cycleContainerLogsTail,
+			Description: gui.Tr.CycleContainerLogsTail,
+		},
 		{
 			ViewName:    "containers",
 			Key:         'c',
@@ -318,6 +325,13 @@ func (gui *Gui) GetInitialKeybindings() []*Binding {
 			Handler:     gui.handleServiceRenderLogsToMain,
 			Description: gui.Tr.ViewLogs,
 		},
+		{
+			ViewName:    "services",
+			Key:         't',
+			Modifier:    gocui.ModNone,
+			Handler:     gui.cycleContainerLogsTail,
+			Description: gui.Tr.CycleContainerLogsTail,
+		},
 		{
 			ViewName:    "services",
 			Key:         'U',

pkg/gui/services_panel.go

@@ -53,7 +53,7 @@ func (gui *Gui) getServicesPanel() *panels.SideListPanel[*commands.Service] {
 				if service.Container == nil {
 					return "services-" + service.ID
 				}
-				return "services-" + service.ID + "-" + service.Container.ID + "-" + service.Container.Container.State
+				return "services-" + service.ID + "-" + service.Container.ID + "-" + service.Container.Container.State + "-" + gui.State.ContainerLogsTail
 			},
 		},
 		ListPanel: panels.ListPanel[*commands.Service]{

pkg/i18n/english.go

@@ -65,6 +65,7 @@ type TranslationSet struct {
 	NextContext                 string
 	Attach                      string
 	ViewLogs                    string
+	CycleContainerLogsTail      string
 	UpProject                   string
 	DownProject                 string
 	ServicesTitle               string
@@ -196,6 +197,7 @@ func englishSet() TranslationSet {
 		NextContext:                 "next tab",
 		Attach:                      "attach",
 		ViewLogs:                    "view logs",
+		CycleContainerLogsTail:      "cycle how many log lines are shown",
 		UpProject:                   "up project",
 		DownProject:                 "down project",
 		RemoveImage:                 "remove image",