feat: support writing audit events to stdout for log

config/flipt.schema.cue

@@ -360,6 +360,7 @@ import "strings"
 			log?: {
 				enabled?: bool | *false
 				file?:    string | *""
+				encoding?:   *"" | "json" | "console"
 			}
 			webhook?: {
 				enabled?:              bool | *false

config/flipt.schema.json

@@ -1219,6 +1219,10 @@
                 "file": {
                   "type": "string",
                   "default": ""
+                },
+                "encoding": {
+                  "type": "string",
+                  "enum": ["json", "console", ""]
                 }
               },
               "title": "Log File"

internal/cmd/grpc.go

@@ -26,7 +26,7 @@ import (
 	"go.flipt.io/flipt/internal/server/analytics/clickhouse"
 	"go.flipt.io/flipt/internal/server/audit"
 	"go.flipt.io/flipt/internal/server/audit/cloud"
-	"go.flipt.io/flipt/internal/server/audit/logfile"
+	"go.flipt.io/flipt/internal/server/audit/log"
 	"go.flipt.io/flipt/internal/server/audit/template"
 	"go.flipt.io/flipt/internal/server/audit/webhook"
 	authnmiddlewaregrpc "go.flipt.io/flipt/internal/server/authn/middleware/grpc"
@@ -392,10 +392,22 @@ func NewGRPCServer(
 	// audit sinks configuration
 	sinks := make([]audit.Sink, 0)
 
-	if cfg.Audit.Sinks.LogFile.Enabled {
-		logFileSink, err := logfile.NewSink(logger, cfg.Audit.Sinks.LogFile.File)
+	if cfg.Audit.Sinks.Log.Enabled {
+		opts := []log.Option{}
+		if cfg.Audit.Sinks.Log.File != "" {
+			opts = append(opts, log.WithPath(cfg.Audit.Sinks.Log.File))
+		}
+
+		if cfg.Audit.Sinks.Log.Encoding != "" {
+			opts = append(opts, log.WithEncoding(cfg.Audit.Sinks.Log.Encoding))
+		} else {
+			// inherit the global log encoding if not specified
+			opts = append(opts, log.WithEncoding(cfg.Log.Encoding))
+		}
+
+		logFileSink, err := log.NewSink(opts...)
 		if err != nil {
-			return nil, fmt.Errorf("opening file at path: %s", cfg.Audit.Sinks.LogFile.File)
+			return nil, fmt.Errorf("creating audit log sink: %w", err)
 		}
 
 		sinks = append(sinks, logFileSink)

internal/config/audit.go

@@ -22,7 +22,7 @@ type AuditConfig struct {
 
 // Enabled returns true if any nested sink is enabled
 func (c AuditConfig) Enabled() bool {
-	return c.Sinks.LogFile.Enabled || c.Sinks.Webhook.Enabled || c.Sinks.Cloud.Enabled
+	return c.Sinks.Log.Enabled || c.Sinks.Webhook.Enabled || c.Sinks.Cloud.Enabled
 }
 
 func (c AuditConfig) IsZero() bool {
@@ -34,7 +34,6 @@ func (c *AuditConfig) setDefaults(v *viper.Viper) error {
 		"sinks": map[string]any{
 			"log": map[string]any{
 				"enabled": "false",
-				"file":    "",
 			},
 			"webhook": map[string]any{
 				"enabled": "false",
@@ -54,10 +53,6 @@ func (c *AuditConfig) setDefaults(v *viper.Viper) error {
 }
 
 func (c *AuditConfig) validate() error {
-	if c.Sinks.LogFile.Enabled && c.Sinks.LogFile.File == "" {
-		return errors.New("file not specified")
-	}
-
 	if c.Sinks.Webhook.Enabled {
 		if c.Sinks.Webhook.URL == "" && len(c.Sinks.Webhook.Templates) == 0 {
 			return errors.New("url or template(s) not provided")
@@ -82,7 +77,7 @@ func (c *AuditConfig) validate() error {
 // SinksConfig contains configuration held in structures for the different sinks
 // that we will send audits to.
 type SinksConfig struct {
-	LogFile LogFileSinkConfig `json:"log,omitempty" mapstructure:"log" yaml:"log,omitempty"`
+	Log     LogSinkConfig     `json:"log,omitempty" mapstructure:"log" yaml:"log,omitempty"`
 	Webhook WebhookSinkConfig `json:"webhook,omitempty" mapstructure:"webhook" yaml:"webhook,omitempty"`
 	Cloud   CloudSinkConfig   `json:"cloud,omitempty" mapstructure:"cloud" yaml:"cloud,omitempty"`
 }
@@ -101,11 +96,12 @@ type WebhookSinkConfig struct {
 	Templates          []WebhookTemplate `json:"templates,omitempty" mapstructure:"templates" yaml:"templates,omitempty"`
 }
 
-// LogFileSinkConfig contains fields that hold configuration for sending audits
-// to a log file.
-type LogFileSinkConfig struct {
-	Enabled bool   `json:"enabled,omitempty" mapstructure:"enabled" yaml:"enabled,omitempty"`
-	File    string `json:"file,omitempty" mapstructure:"file" yaml:"file,omitempty"`
+// LogSinkConfig contains fields that hold configuration for sending audits
+// to a log.
+type LogSinkConfig struct {
+	Enabled  bool        `json:"enabled,omitempty" mapstructure:"enabled" yaml:"enabled,omitempty"`
+	File     string      `json:"file,omitempty" mapstructure:"file" yaml:"file,omitempty"`
+	Encoding LogEncoding `json:"encoding,omitempty" mapstructure:"encoding" yaml:"encoding,omitempty"`
 }
 
 // BufferConfig holds configuration for the buffering of sending the audit

internal/config/config.go

@@ -33,7 +33,6 @@ var (
 var DecodeHooks = []mapstructure.DecodeHookFunc{
 	mapstructure.StringToTimeDurationHookFunc(),
 	stringToSliceHookFunc(),
-	stringToEnumHookFunc(stringToLogEncoding),
 	stringToEnumHookFunc(stringToCacheBackend),
 	stringToEnumHookFunc(stringToTracingExporter),
 	stringToEnumHookFunc(stringToScheme),
@@ -619,7 +618,7 @@ func Default() *Config {
 
 		Audit: AuditConfig{
 			Sinks: SinksConfig{
-				LogFile: LogFileSinkConfig{
+				Log: LogSinkConfig{
 					Enabled: false,
 					File:    "",
 				},

internal/config/config_test.go

@@ -738,7 +738,7 @@ func TestLoad(t *testing.T) {
 
 				cfg.Audit = AuditConfig{
 					Sinks: SinksConfig{
-						LogFile: LogFileSinkConfig{
+						Log: LogSinkConfig{
 							Enabled: true,
 							File:    "/path/to/logs.txt",
 						},
@@ -942,9 +942,13 @@ func TestLoad(t *testing.T) {
 			wantErr: errors.New("flush period below 2 minutes or greater than 5 minutes"),
 		},
 		{
-			name:    "file not specified",
-			path:    "./testdata/audit/invalid_enable_without_file.yml",
-			wantErr: errors.New("file not specified"),
+			name: "file not specified",
+			path: "./testdata/audit/enable_without_file.yml",
+			expected: func() *Config {
+				cfg := Default()
+				cfg.Audit.Sinks.Log.Enabled = true
+				return cfg
+			},
 		},
 		{
 			name:    "url or template not specified",

internal/config/log.go

@@ -41,30 +41,16 @@ func (c *LogConfig) setDefaults(v *viper.Viper) error {
 	return nil
 }
 
-var (
-	logEncodingToString = [...]string{
-		LogEncodingConsole: "console",
-		LogEncodingJSON:    "json",
-	}
-
-	stringToLogEncoding = map[string]LogEncoding{
-		"console": LogEncodingConsole,
-		"json":    LogEncodingJSON,
-	}
-)
-
 // LogEncoding is either console or JSON.
-// TODO: can we use a string instead?
-type LogEncoding uint8
+type LogEncoding string
 
 const (
-	_ LogEncoding = iota
-	LogEncodingConsole
-	LogEncodingJSON
+	LogEncodingConsole = LogEncoding("console")
+	LogEncodingJSON    = LogEncoding("json")
 )
 
 func (e LogEncoding) String() string {
-	return logEncodingToString[e]
+	return string(e)
 }
 
 func (e LogEncoding) MarshalJSON() ([]byte, error) {

internal/server/audit/audit.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io"
 
 	"github.com/hashicorp/go-multierror"
 	sdktrace "go.opentelemetry.io/otel/sdk/trace"
@@ -14,7 +15,7 @@ import (
 // that Flipt will support.
 type Sink interface {
 	SendAudits(context.Context, []Event) error
-	Close() error
+	io.Closer
 	fmt.Stringer
 }
 

internal/server/audit/log/log.go

@@ -0,0 +1,141 @@
+package log
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"go.flipt.io/flipt/internal/config"
+	"go.flipt.io/flipt/internal/server/audit"
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+)
+
+const (
+	sinkType = "log"
+	auditKey = "AUDIT"
+)
+
+// Sink is the structure in charge of sending audit events to a specified file location.
+type Sink struct {
+	logger *zap.Logger
+}
+
+type logOptions struct {
+	path     string
+	encoding config.LogEncoding
+}
+
+type Option func(*logOptions)
+
+func WithPath(path string) Option {
+	return func(o *logOptions) {
+		o.path = path
+	}
+}
+
+func WithEncoding(encoding config.LogEncoding) Option {
+	return func(o *logOptions) {
+		o.encoding = encoding
+	}
+}
+
+// NewSink is the constructor for a Sink.
+func NewSink(opts ...Option) (audit.Sink, error) {
+	oo := &logOptions{}
+
+	for _, o := range opts {
+		o(oo)
+	}
+
+	return newSink(*oo)
+}
+
+var (
+	consoleEncoderConfig = zapcore.EncoderConfig{
+		TimeKey:        "T",
+		LevelKey:       zapcore.OmitKey,
+		NameKey:        "N",
+		CallerKey:      zapcore.OmitKey,
+		FunctionKey:    zapcore.OmitKey,
+		MessageKey:     "M",
+		StacktraceKey:  zapcore.OmitKey,
+		LineEnding:     zapcore.DefaultLineEnding,
+		EncodeLevel:    zapcore.CapitalColorLevelEncoder,
+		EncodeTime:     zapcore.RFC3339TimeEncoder,
+		EncodeDuration: zapcore.StringDurationEncoder,
+		EncodeCaller:   zapcore.ShortCallerEncoder,
+	}
+
+	fileEncoderConfig = zapcore.EncoderConfig{
+		TimeKey:        zapcore.OmitKey,
+		LevelKey:       zapcore.OmitKey,
+		NameKey:        zapcore.OmitKey,
+		CallerKey:      zapcore.OmitKey,
+		FunctionKey:    zapcore.OmitKey,
+		MessageKey:     zapcore.OmitKey,
+		StacktraceKey:  zapcore.OmitKey,
+		LineEnding:     zapcore.DefaultLineEnding,
+		EncodeLevel:    zapcore.CapitalColorLevelEncoder,
+		EncodeTime:     zapcore.RFC3339TimeEncoder,
+		EncodeDuration: zapcore.StringDurationEncoder,
+		EncodeCaller:   zapcore.ShortCallerEncoder,
+	}
+)
+
+// newSink is the constructor for a Sink visible for testing.
+func newSink(opts logOptions) (audit.Sink, error) {
+	cfg := zap.Config{
+		Level:            zap.NewAtomicLevelAt(zapcore.InfoLevel),
+		Development:      false,
+		Encoding:         "console",
+		EncoderConfig:    consoleEncoderConfig,
+		OutputPaths:      []string{"stdout"},
+		ErrorOutputPaths: []string{"stderr"},
+	}
+
+	if opts.encoding != "" {
+		cfg.Encoding = string(opts.encoding)
+	}
+
+	if opts.path != "" {
+		// check path dir exists, if not create it
+		dir := filepath.Dir(opts.path)
+		if _, err := os.Stat(dir); err != nil {
+			if !os.IsNotExist(err) {
+				return nil, fmt.Errorf("checking log file path: %w", err)
+			}
+
+			if err := os.MkdirAll(dir, 0755); err != nil {
+				return nil, fmt.Errorf("creating log file path: %w", err)
+			}
+		}
+
+		cfg.OutputPaths = []string{opts.path}
+		cfg.EncoderConfig = fileEncoderConfig
+	}
+
+	return &Sink{
+		logger: zap.Must(cfg.Build()),
+	}, nil
+}
+
+func (l *Sink) SendAudits(_ context.Context, events []audit.Event) error {
+	for _, e := range events {
+		l.logger.Info(auditKey, zap.Any("event", e))
+	}
+
+	return nil
+}
+
+func (l *Sink) Close() error {
+	// see: https://github.com/uber-go/zap/issues/991
+	//nolint:errcheck
+	_ = l.logger.Sync()
+	return nil
+}
+
+func (l *Sink) String() string {
+	return sinkType
+}