fix: reconnect to the logs stream in dashboard after reboot

The log stream displayed in the dashboard was stopping to work when a node was rebooted.
Rework the log data source to establish a per-node connection and use a retry loop to always reconnect until the dashboard is terminated.

Print the connection errors in the log stream in red color.

Closes #8388.

Signed-off-by: Utku Ozdemir <utku.ozdemir@siderolabs.com>

Author: utkuozdemir

internal/pkg/dashboard/components/logviewer.go

@@ -23,6 +23,7 @@ func NewLogViewer() *LogViewer {
 	}
 
 	widget.logs.ScrollToEnd().
+		SetDynamicColors(true).
 		SetMaxLines(maxLogLines).
 		SetText(noData).
 		SetBorderPadding(0, 0, 1, 1).
@@ -54,7 +55,12 @@ func NewLogViewer() *LogViewer {
 }
 
 // WriteLog writes the log line to the widget.
-func (widget *LogViewer) WriteLog(logLine string) {
+func (widget *LogViewer) WriteLog(logLine, logError string) {
+	if logError != "" {
+		logLine = "[red]" + tview.Escape(logError) + "[-]\n"
+	} else {
+		logLine = tview.Escape(logLine) + "\n"
+	}
+
 	widget.logs.Write([]byte(logLine)) //nolint:errcheck
-	widget.logs.Write([]byte("\n"))    //nolint:errcheck
 }

internal/pkg/dashboard/dashboard.go

@@ -70,7 +70,7 @@ type ResourceDataListener interface {
 
 // LogDataListener is a listener which is notified when a log line is received.
 type LogDataListener interface {
-	OnLogDataChange(node string, logLine string)
+	OnLogDataChange(node, logLine, logError string)
 }
 
 // NodeSelectListener is a listener which is notified when a node is selected.
@@ -376,10 +376,7 @@ func (d *Dashboard) startDataHandler(ctx context.Context) func() error {
 		defer d.resourceDataSource.Stop() //nolint:errcheck
 
 		// start logs data source
-		if err := d.logDataSource.Start(ctx); err != nil {
-			return err
-		}
-
+		d.logDataSource.Start(ctx)
 		defer d.logDataSource.Stop() //nolint:errcheck
 
 		lastLogTime := time.Now()
@@ -393,11 +390,11 @@ func (d *Dashboard) startDataHandler(ctx context.Context) func() error {
 
 				if time.Since(lastLogTime) < 50*time.Millisecond {
 					d.app.QueueUpdate(func() {
-						d.processLog(nodeAlias, nodeLog.Log)
+						d.processLog(nodeAlias, nodeLog.Log, nodeLog.Error)
 					})
 				} else {
 					d.app.QueueUpdateDraw(func() {
-						d.processLog(nodeAlias, nodeLog.Log)
+						d.processLog(nodeAlias, nodeLog.Log, nodeLog.Error)
 					})
 				}
 
@@ -461,9 +458,9 @@ func (d *Dashboard) processNodeResource(nodeResource resourcedata.Data) {
 }
 
 // processLog re-renders the log components with new log data.
-func (d *Dashboard) processLog(node, line string) {
+func (d *Dashboard) processLog(node, logLine, logError string) {
 	for _, component := range d.logDataListeners {
-		component.OnLogDataChange(node, line)
+		component.OnLogDataChange(node, logLine, logError)
 	}
 }
 

internal/pkg/dashboard/logdata/logdata.go

@@ -8,20 +8,26 @@ package logdata
 import (
 	"context"
 	"errors"
+	"fmt"
 	"strings"
 	"sync"
+	"time"
 
 	"golang.org/x/sync/errgroup"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
 
 	"github.com/siderolabs/talos/cmd/talosctl/pkg/talos/helpers"
+	"github.com/siderolabs/talos/internal/pkg/dashboard/util"
 	"github.com/siderolabs/talos/pkg/machinery/api/common"
 	"github.com/siderolabs/talos/pkg/machinery/client"
 )
 
 // Data is a log line from a node.
 type Data struct {
-	Node string
-	Log  string
+	Node  string
+	Log   string
+	Error string
 }
 
 // Source is a data source for Kernel (dmesg) logs.
@@ -45,14 +51,10 @@ func NewSource(client *client.Client) *Source {
 }
 
 // Start starts the data source.
-func (source *Source) Start(ctx context.Context) error {
-	var err error
-
+func (source *Source) Start(ctx context.Context) {
 	source.once.Do(func() {
-		err = source.start(ctx)
+		source.start(ctx)
 	})
-
-	return err
 }
 
 // Stop stops the data source.
@@ -62,38 +64,70 @@ func (source *Source) Stop() error {
 	return source.eg.Wait()
 }
 
-func (source *Source) start(ctx context.Context) error {
+func (source *Source) start(ctx context.Context) {
 	ctx, source.logCtxCancel = context.WithCancel(ctx)
 
-	dmesgStream, err := source.client.Dmesg(ctx, true, false)
-	if err != nil {
-		return err
+	for _, nodeContext := range util.NodeContexts(ctx) {
+		source.eg.Go(func() error {
+			return source.tailNodeWithRetries(nodeContext.Ctx, nodeContext.Node)
+		})
 	}
+}
 
-	source.eg.Go(func() error {
-		return helpers.ReadGRPCStream(dmesgStream, func(data *common.Data, node string, multipleNodes bool) error {
-			if len(data.Bytes) == 0 {
-				return nil
-			}
+func (source *Source) tailNodeWithRetries(ctx context.Context, node string) error {
+	for {
+		readErr := source.readDmesg(ctx, node)
+		if errors.Is(readErr, context.Canceled) || status.Code(readErr) == codes.Canceled {
+			return nil
+		}
 
-			line := strings.TrimSpace(string(data.Bytes))
-			if line == "" {
-				return nil
-			}
+		if readErr != nil {
+			source.LogCh <- Data{Node: node, Error: readErr.Error()}
+		}
 
-			select {
-			case <-ctx.Done():
-				if errors.Is(ctx.Err(), context.Canceled) {
-					return nil
-				}
+		// back off a bit before retrying
+		sleepWithContext(ctx, 30*time.Second)
+	}
+}
 
-				return ctx.Err()
-			case source.LogCh <- Data{Node: node, Log: line}:
-			}
+func (source *Source) readDmesg(ctx context.Context, node string) error {
+	dmesgStream, err := source.client.Dmesg(ctx, true, false)
+	if err != nil {
+		return fmt.Errorf("dashboard: error opening dmesg stream: %w", err)
+	}
 
+	readErr := helpers.ReadGRPCStream(dmesgStream, func(data *common.Data, _ string, _ bool) error {
+		if len(data.Bytes) == 0 {
 			return nil
-		})
+		}
+
+		line := strings.TrimSpace(string(data.Bytes))
+		if line == "" {
+			return nil
+		}
+
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		case source.LogCh <- Data{Node: node, Log: line}:
+		}
+
+		return nil
 	})
+	if readErr != nil {
+		return fmt.Errorf("error reading dmesg stream: %w", readErr)
+	}
 
 	return nil
 }
+
+func sleepWithContext(ctx context.Context, d time.Duration) {
+	timer := time.NewTimer(d)
+	select {
+	case <-ctx.Done():
+		if !timer.Stop() {
+			<-timer.C
+		}
+	case <-timer.C:
+	}
+}

internal/pkg/dashboard/resourcedata/resourcedata.go

@@ -16,9 +16,8 @@ import (
 	"github.com/cosi-project/runtime/pkg/state"
 	"github.com/siderolabs/gen/channel"
 	"golang.org/x/sync/errgroup"
-	"google.golang.org/grpc/metadata"
 
-	"github.com/siderolabs/talos/pkg/machinery/client"
+	"github.com/siderolabs/talos/internal/pkg/dashboard/util"
 	"github.com/siderolabs/talos/pkg/machinery/constants"
 	"github.com/siderolabs/talos/pkg/machinery/resources/cluster"
 	"github.com/siderolabs/talos/pkg/machinery/resources/config"
@@ -70,10 +69,9 @@ func (source *Source) run(ctx context.Context) {
 
 	source.NodeResourceCh = source.ch
 
-	nodes := source.nodes(ctx)
-	for _, node := range nodes {
+	for _, nodeContext := range util.NodeContexts(ctx) {
 		source.eg.Go(func() error {
-			source.runResourceWatchWithRetries(ctx, node)
+			source.runResourceWatchWithRetries(nodeContext.Ctx, nodeContext.Node)
 
 			return nil
 		})
@@ -101,10 +99,6 @@ func (source *Source) runResourceWatchWithRetries(ctx context.Context, node stri
 
 //nolint:gocyclo,cyclop
 func (source *Source) runResourceWatch(ctx context.Context, node string) error {
-	if node != "" {
-		ctx = client.WithNode(ctx, node)
-	}
-
 	ctx, cancel := context.WithCancel(ctx)
 	defer cancel()
 
@@ -211,22 +205,3 @@ func (source *Source) runResourceWatch(ctx context.Context, node string) error {
 		}
 	}
 }
-
-func (source *Source) nodes(ctx context.Context) []string {
-	md, mdOk := metadata.FromOutgoingContext(ctx)
-	if !mdOk {
-		return []string{""} // local node
-	}
-
-	nodeVal := md.Get("node")
-	if len(nodeVal) > 0 {
-		return []string{nodeVal[0]}
-	}
-
-	nodesVal := md.Get("nodes")
-	if len(nodesVal) == 0 {
-		return []string{""} // local node
-	}
-
-	return nodesVal
-}

internal/pkg/dashboard/summary.go

@@ -91,8 +91,8 @@ func (widget *SummaryGrid) OnResourceDataChange(nodeResource resourcedata.Data)
 }
 
 // OnLogDataChange implements the LogDataListener interface.
-func (widget *SummaryGrid) OnLogDataChange(node string, logLine string) {
-	widget.logViewer(node).WriteLog(logLine)
+func (widget *SummaryGrid) OnLogDataChange(node, logLine, logError string) {
+	widget.logViewer(node).WriteLog(logLine, logError)
 }
 
 func (widget *SummaryGrid) updateLogViewer() {

internal/pkg/dashboard/util/util.go

@@ -0,0 +1,49 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+// Package util provides utility functions for the dashboard.
+package util
+
+import (
+	"context"
+
+	"google.golang.org/grpc/metadata"
+
+	"github.com/siderolabs/talos/pkg/machinery/client"
+)
+
+// NodeContext contains the context.Context for a single node and the node name.
+type NodeContext struct {
+	Ctx  context.Context //nolint:containedctx
+	Node string
+}
+
+// NodeContexts returns a list of NodeContexts from the given context.
+//
+// It extracts the node names from the outgoing GRPC context metadata.
+// If the node name is not present in the metadata, context will be returned as-is with an empty node name.
+func NodeContexts(ctx context.Context) []NodeContext {
+	md, mdOk := metadata.FromOutgoingContext(ctx)
+	if !mdOk {
+		return []NodeContext{{Ctx: ctx}}
+	}
+
+	nodeVal := md.Get("node")
+	if len(nodeVal) > 0 {
+		return []NodeContext{{Ctx: ctx, Node: nodeVal[0]}}
+	}
+
+	nodesVal := md.Get("nodes")
+	if len(nodesVal) == 0 {
+		return []NodeContext{{Ctx: ctx}}
+	}
+
+	nodeContexts := make([]NodeContext, 0, len(nodesVal))
+
+	for _, node := range nodesVal {
+		nodeContexts = append(nodeContexts, NodeContext{Ctx: client.WithNode(ctx, node), Node: node})
+	}
+
+	return nodeContexts
+}