server: add support for log rotation

Signed-off-by: Sam Batschelet <sbatsche@redhat.com>

server/embed/config.go

@@ -68,6 +68,15 @@ const (
 	StdErrLogOutput  = "stderr"
 	StdOutLogOutput  = "stdout"
 
+	// DefaultLogRotationConfig is the default configuration used for log rotation.
+	// Log rotation is disabled by default.
+	// MaxSize    = 100 // MB
+	// MaxAge     = 0 // days (no limit)
+	// MaxBackups = 0 // no limit
+	// LocalTime  = false // use computers local time, UTC by default
+	// Compress   = false // compress the rotated log in gzip format
+	DefaultLogRotationConfig = `{"maxsize": 100, "maxage": 0, "maxbackups": 0, "localtime": false, "compress": false}`
+
 	// DefaultStrictReconfigCheck is the default value for "--strict-reconfig-check" flag.
 	// It's enabled by default.
 	DefaultStrictReconfigCheck = true
@@ -86,6 +95,7 @@ var (
 	ErrConflictBootstrapFlags = fmt.Errorf("multiple discovery or bootstrap flags are set. " +
 		"Choose one of \"initial-cluster\", \"discovery\" or \"discovery-srv\"")
 	ErrUnsetAdvertiseClientURLsFlag = fmt.Errorf("--advertise-client-urls is required when --listen-client-urls is set explicitly")
+	ErrLogRotationInvalidLogOutput  = fmt.Errorf("--log-outputs requires a single file path when --log-rotate-config-json is defined")
 
 	DefaultInitialAdvertisePeerURLs = "http://localhost:2380"
 	DefaultAdvertiseClientURLs      = "http://localhost:2379"
@@ -320,7 +330,10 @@ type Config struct {
 	//  - file path to append server logs to.
 	// It can be multiple when "Logger" is zap.
 	LogOutputs []string `json:"log-outputs"`
-
+	// EnableLogRotation enables log rotation of a single LogOutputs file target.
+	EnableLogRotation bool `json:"enable-log-rotation"`
+	// LogRotationConfigJSON is a passthrough allowing a log rotation JSON config to be passed directly.
+	LogRotationConfigJSON string `json:"log-rotation-config-json"`
 	// ZapLoggerBuilder is used to build the zap logger.
 	ZapLoggerBuilder func(*Config) error
 
@@ -437,12 +450,14 @@ func NewConfig() *Config {
 
 		PreVote: true,
 
-		loggerMu:          new(sync.RWMutex),
-		logger:            nil,
-		Logger:            "zap",
-		LogOutputs:        []string{DefaultLogOutput},
-		LogLevel:          logutil.DefaultLogLevel,
-		EnableGRPCGateway: true,
+		loggerMu:              new(sync.RWMutex),
+		logger:                nil,
+		Logger:                "zap",
+		LogOutputs:            []string{DefaultLogOutput},
+		LogLevel:              logutil.DefaultLogLevel,
+		EnableLogRotation:     false,
+		LogRotationConfigJSON: DefaultLogRotationConfig,
+		EnableGRPCGateway:     true,
 
 		ExperimentalDowngradeCheckTime: DefaultDowngradeCheckTime,
 		ExperimentalMemoryMlock:        false,