cmd: add a diode to avoid log blocking

cmd/conntrack-fixer.go

@@ -49,7 +49,7 @@ containers started with the label "akvorado.conntrack.fix=1".`,
 			return fmt.Errorf("unable to initialize conntrack fixer component: %w", err)
 		}
 		addCommonHTTPHandlers(r, "conntrack-fixer", httpComponent)
-		versionMetrics(r)
+		moreMetrics(r)
 
 		components := []any{
 			httpComponent,

cmd/console.go

@@ -123,7 +123,7 @@ func consoleStart(r *reporter.Reporter, config ConsoleConfiguration, checkOnly b
 
 	// Expose some information and metrics
 	addCommonHTTPHandlers(r, "console", httpComponent)
-	versionMetrics(r)
+	moreMetrics(r)
 
 	// If we only asked for a check, stop here.
 	if checkOnly {

cmd/demo-exporter.go

@@ -116,7 +116,7 @@ func demoExporterStart(r *reporter.Reporter, config DemoExporterConfiguration, c
 
 	// Expose some information and metrics
 	addCommonHTTPHandlers(r, "demo-exporter", httpComponent)
-	versionMetrics(r)
+	moreMetrics(r)
 
 	// If we only asked for a check, stop here.
 	if checkOnly {

cmd/inlet.go

@@ -100,7 +100,7 @@ func inletStart(r *reporter.Reporter, config InletConfiguration, checkOnly bool)
 
 	// Expose some information and metrics
 	addCommonHTTPHandlers(r, "inlet", httpComponent)
-	versionMetrics(r)
+	moreMetrics(r)
 
 	// If we only asked for a check, stop here.
 	if checkOnly {

cmd/orchestrator.go

@@ -190,7 +190,7 @@ func orchestratorStart(r *reporter.Reporter, config OrchestratorConfiguration, c
 
 	// Expose some information and metrics
 	addCommonHTTPHandlers(r, "orchestrator", httpComponent)
-	versionMetrics(r)
+	moreMetrics(r)
 
 	// If we only asked for a check, stop here.
 	if checkOnly {

cmd/outlet.go

@@ -164,7 +164,7 @@ func outletStart(r *reporter.Reporter, config OutletConfiguration, checkOnly boo
 
 	// Expose some information and metrics
 	addCommonHTTPHandlers(r, "outlet", httpComponent)
-	versionMetrics(r)
+	moreMetrics(r)
 
 	// If we only asked for a check, stop here.
 	if checkOnly {

cmd/root.go

@@ -6,14 +6,23 @@ package cmd
 
 import (
 	"os"
+	"runtime"
+	"sync/atomic"
+
+	"akvorado/common/helpers"
+	"akvorado/common/reporter"
 
 	"github.com/mattn/go-isatty"
 	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/diode"
 	"github.com/rs/zerolog/log"
 	"github.com/spf13/cobra"
 )
 
-var debug bool
+var (
+	debug      bool
+	missedLogs atomic.Uint64
+)
 
 // RootCmd is the root for all commands
 var RootCmd = &cobra.Command{
@@ -23,7 +32,10 @@ var RootCmd = &cobra.Command{
 		if isatty.IsTerminal(os.Stdout.Fd()) {
 			log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr})
 		} else {
-			log.Logger = zerolog.New(os.Stdout).With().Timestamp().Logger()
+			w := diode.NewWriter(os.Stdout, 1000, 0, func(missed int) {
+				missedLogs.Add(uint64(missed))
+			})
+			log.Logger = zerolog.New(w).With().Timestamp().Logger()
 		}
 		zerolog.SetGlobalLevel(zerolog.InfoLevel)
 		if debug {
@@ -34,6 +46,21 @@ var RootCmd = &cobra.Command{
 	SilenceUsage:  true,
 }
 
+func moreMetrics(r *reporter.Reporter) {
+	versionMetrics(r)
+	r.GaugeFunc(reporter.GaugeOpts{
+		Name: "dropped_log_messages",
+		Help: "Number of log messages dropped.",
+	}, func() float64 {
+		return float64(missedLogs.Load())
+	})
+	r.GaugeVec(reporter.GaugeOpts{
+		Name: "info",
+		Help: "Akvorado build information",
+	}, []string{"version", "compiler"}).
+		WithLabelValues(helpers.AkvoradoVersion, runtime.Version()).Set(1)
+}
+
 func init() {
 	RootCmd.PersistentFlags().BoolVarP(&debug, "debug", "d", false,
 		"Enable debug logs")