Ignore sync errors in a consistent way

cmd/digest.go

@@ -6,6 +6,7 @@ import (
 	"log"
 
 	"github.com/compliance-framework/api/internal/config"
+	"github.com/compliance-framework/api/internal/logging"
 	"github.com/compliance-framework/api/internal/service"
 	"github.com/compliance-framework/api/internal/service/digest"
 	"github.com/compliance-framework/api/internal/service/email"
@@ -53,7 +54,7 @@ func runDigestTest(cmd *cobra.Command, args []string) {
 	}
 
 	defer func() {
-		if err := sugar.Sync(); err != nil {
+		if err := sugar.Sync(); !logging.IgnoreSyncError(err) {
 			log.Printf("failed to sync zap logger: %v", err)
 		}
 	}()
@@ -144,7 +145,7 @@ func runDigestPreview(cmd *cobra.Command, args []string) {
 	}
 
 	defer func() {
-		if err := sugar.Sync(); err != nil {
+		if err := sugar.Sync(); !logging.IgnoreSyncError(err) {
 			log.Printf("failed to sync zap logger: %v", err)
 		}
 	}()

cmd/riskdigest.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	"github.com/compliance-framework/api/internal/config"
+	"github.com/compliance-framework/api/internal/logging"
 	"github.com/compliance-framework/api/internal/service"
 	"github.com/compliance-framework/api/internal/service/email"
 	slacksvc "github.com/compliance-framework/api/internal/service/slack"
@@ -47,7 +48,7 @@ func runRiskDigestTest(cmd *cobra.Command, args []string) {
 	}
 
 	defer func() {
-		if err := sugar.Sync(); err != nil {
+		if err := sugar.Sync(); !logging.IgnoreSyncError(err) {
 			log.Printf("failed to sync zap logger: %v", err)
 		}
 	}()

cmd/run.go

@@ -11,6 +11,7 @@ import (
 	"github.com/compliance-framework/api/internal/api/handler/auth"
 	"github.com/compliance-framework/api/internal/api/handler/oscal"
 	"github.com/compliance-framework/api/internal/config"
+	"github.com/compliance-framework/api/internal/logging"
 	"github.com/compliance-framework/api/internal/service"
 	"github.com/compliance-framework/api/internal/service/digest"
 	"github.com/compliance-framework/api/internal/service/email"
@@ -45,7 +46,7 @@ func RunServer(cmd *cobra.Command, args []string) {
 	}
 
 	defer func() {
-		if err := sugar.Sync(); err != nil {
+		if err := sugar.Sync(); !logging.IgnoreSyncError(err) {
 			log.Printf("failed to sync zap logger: %v", err)
 		}
 	}()

cmd/users/create.go

@@ -7,6 +7,7 @@ import (
 	"math/big"
 
 	"github.com/compliance-framework/api/internal/config"
+	"github.com/compliance-framework/api/internal/logging"
 	"github.com/compliance-framework/api/internal/service"
 	"github.com/compliance-framework/api/internal/service/relational"
 	"github.com/spf13/cobra"
@@ -45,7 +46,7 @@ func addUser(cmd *cobra.Command, args []string) {
 	cobra.CheckErr(err)
 	defer func() {
 		err := logger.Sync()
-		if err != nil {
+		if !logging.IgnoreSyncError(err) {
 			println("failed to sync logger:", err.Error())
 		}
 	}()

cmd/users/update.go

@@ -4,6 +4,7 @@ import (
 	"context"
 
 	"github.com/compliance-framework/api/internal/config"
+	"github.com/compliance-framework/api/internal/logging"
 	"github.com/compliance-framework/api/internal/service"
 	"github.com/compliance-framework/api/internal/service/relational"
 	"github.com/spf13/cobra"
@@ -40,7 +41,7 @@ func updateUser(cmd *cobra.Command, args []string) {
 	cobra.CheckErr(err)
 	defer func() {
 		err := logger.Sync()
-		if err != nil {
+		if !logging.IgnoreSyncError(err) {
 			println("failed to sync logger:", err.Error())
 		}
 	}()

internal/logging/sync.go

@@ -0,0 +1,14 @@
+package logging
+
+import (
+	"errors"
+	"syscall"
+)
+
+// IgnoreSyncError filters the known benign sync errors returned when zap flushes
+// stdout/stderr-backed loggers on some platforms and runtimes.
+func IgnoreSyncError(err error) bool {
+	return err == nil ||
+		errors.Is(err, syscall.EINVAL) ||
+		errors.Is(err, syscall.ENOTTY)
+}

internal/logging/sync_test.go

@@ -0,0 +1,30 @@
+package logging
+
+import (
+	"errors"
+	"syscall"
+	"testing"
+)
+
+// Test the catching of sync errors
+func TestIgnoreSyncError(t *testing.T) {
+	tests := []struct {
+		name string
+		err  error
+		want bool
+	}{
+		{name: "nil", err: nil, want: true},
+		{name: "EINVAL", err: syscall.EINVAL, want: true},
+		{name: "wrapped EINVAL", err: errors.New("sync: " + syscall.EINVAL.Error()), want: false},
+		{name: "ENOTTY", err: syscall.ENOTTY, want: true},
+		{name: "other", err: syscall.EBADF, want: false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := IgnoreSyncError(tt.err); got != tt.want {
+				t.Fatalf("IgnoreSyncError(%v) = %v, want %v", tt.err, got, tt.want)
+			}
+		})
+	}
+}