Allow configurable stacktrace encoding

This PR adds a `StacktraceEncoder` type to the `EncoderConfig` struct

Users can override the `EncodeStacktrace` field to configure how stacktraces are outputed
This PR aims to resolve uber-go#514 by mirroring the behavior of the `EncodeCaller` field

The `EncodeStacktrace` field has been inserted as a required field, and has been added to `NewDevelopmentConfig` and `NewProductionConfig`
as sane defaults however, it is currently a required field and can cause a panic if a user is manually building their config without these helpers.

config.go

@@ -123,18 +123,19 @@ type Config struct {
 //	cfg.EncodeTime = zapcore.ISO8601TimeEncoder
 func NewProductionEncoderConfig() zapcore.EncoderConfig {
 	return zapcore.EncoderConfig{
-		TimeKey:        "ts",
-		LevelKey:       "level",
-		NameKey:        "logger",
-		CallerKey:      "caller",
-		FunctionKey:    zapcore.OmitKey,
-		MessageKey:     "msg",
-		StacktraceKey:  "stacktrace",
-		LineEnding:     zapcore.DefaultLineEnding,
-		EncodeLevel:    zapcore.LowercaseLevelEncoder,
-		EncodeTime:     zapcore.EpochTimeEncoder,
-		EncodeDuration: zapcore.SecondsDurationEncoder,
-		EncodeCaller:   zapcore.ShortCallerEncoder,
+		TimeKey:          "ts",
+		LevelKey:         "level",
+		NameKey:          "logger",
+		CallerKey:        "caller",
+		FunctionKey:      zapcore.OmitKey,
+		MessageKey:       "msg",
+		StacktraceKey:    "stacktrace",
+		LineEnding:       zapcore.DefaultLineEnding,
+		EncodeLevel:      zapcore.LowercaseLevelEncoder,
+		EncodeTime:       zapcore.EpochTimeEncoder,
+		EncodeDuration:   zapcore.SecondsDurationEncoder,
+		EncodeCaller:     zapcore.ShortCallerEncoder,
+		EncodeStacktrace: zapcore.FullStacktraceEncoder,
 	}
 }
 
@@ -200,18 +201,19 @@ func NewProductionConfig() Config {
 func NewDevelopmentEncoderConfig() zapcore.EncoderConfig {
 	return zapcore.EncoderConfig{
 		// Keys can be anything except the empty string.
-		TimeKey:        "T",
-		LevelKey:       "L",
-		NameKey:        "N",
-		CallerKey:      "C",
-		FunctionKey:    zapcore.OmitKey,
-		MessageKey:     "M",
-		StacktraceKey:  "S",
-		LineEnding:     zapcore.DefaultLineEnding,
-		EncodeLevel:    zapcore.CapitalLevelEncoder,
-		EncodeTime:     zapcore.ISO8601TimeEncoder,
-		EncodeDuration: zapcore.StringDurationEncoder,
-		EncodeCaller:   zapcore.ShortCallerEncoder,
+		TimeKey:          "T",
+		LevelKey:         "L",
+		NameKey:          "N",
+		CallerKey:        "C",
+		FunctionKey:      zapcore.OmitKey,
+		MessageKey:       "M",
+		StacktraceKey:    "S",
+		LineEnding:       zapcore.DefaultLineEnding,
+		EncodeLevel:      zapcore.CapitalLevelEncoder,
+		EncodeTime:       zapcore.ISO8601TimeEncoder,
+		EncodeDuration:   zapcore.StringDurationEncoder,
+		EncodeCaller:     zapcore.ShortCallerEncoder,
+		EncodeStacktrace: zapcore.FullStacktraceEncoder,
 	}
 }
 

zapcore/console_encoder.go

@@ -101,6 +101,7 @@ func (c consoleEncoder) EncodeEntry(ent Entry, fields []Field) (*buffer.Buffer,
 			arr.AppendString(ent.Caller.Function)
 		}
 	}
+
 	for i := range arr.elems {
 		if i > 0 {
 			line.AppendString(c.ConsoleSeparator)
@@ -119,10 +120,23 @@ func (c consoleEncoder) EncodeEntry(ent Entry, fields []Field) (*buffer.Buffer,
 	c.writeContext(line, fields)
 
 	// If there's no stacktrace key, honor that; this allows users to force
-	// single-line output.
+	// single-line output by avoiding printing the stacktrace.
 	if ent.Stack != "" && c.StacktraceKey != "" {
 		line.AppendByte('\n')
-		line.AppendString(ent.Stack)
+
+		if c.EncodeStacktrace != nil {
+			arr = getSliceEncoder()
+			c.EncodeStacktrace(ent.Stack, arr)
+			for i := range arr.elems {
+				if i > 0 {
+					line.AppendString(c.ConsoleSeparator)
+				}
+				fmt.Fprint(line, arr.elems[i])
+			}
+			putSliceEncoder(arr)
+		} else {
+			line.AppendString(ent.Stack)
+		}
 	}
 
 	line.AppendString(c.LineEnding)

zapcore/encoder.go

@@ -270,6 +270,18 @@ func (e *DurationEncoder) UnmarshalText(text []byte) error {
 	return nil
 }
 
+// A StacktraceEncoder serializes a stacktrace
+//
+// This function must make exactly one call
+// to a PrimitiveArrayEncoder's Append* method.
+type StacktraceEncoder func(string, PrimitiveArrayEncoder)
+
+// FullStacktraceEncoder passes down the full stacktrace as a string to the enc
+func FullStacktraceEncoder(stacktrace string, enc PrimitiveArrayEncoder) {
+	// TODO: consider using a byte-oriented API to save an allocation.
+	enc.AppendString(stacktrace)
+}
+
 // A CallerEncoder serializes an EntryCaller to a primitive type.
 //
 // This function must make exactly one call
@@ -343,10 +355,11 @@ type EncoderConfig struct {
 	// Configure the primitive representations of common complex types. For
 	// example, some users may want all time.Times serialized as floating-point
 	// seconds since epoch, while others may prefer ISO8601 strings.
-	EncodeLevel    LevelEncoder    `json:"levelEncoder" yaml:"levelEncoder"`
-	EncodeTime     TimeEncoder     `json:"timeEncoder" yaml:"timeEncoder"`
-	EncodeDuration DurationEncoder `json:"durationEncoder" yaml:"durationEncoder"`
-	EncodeCaller   CallerEncoder   `json:"callerEncoder" yaml:"callerEncoder"`
+	EncodeLevel      LevelEncoder      `json:"levelEncoder" yaml:"levelEncoder"`
+	EncodeTime       TimeEncoder       `json:"timeEncoder" yaml:"timeEncoder"`
+	EncodeDuration   DurationEncoder   `json:"durationEncoder" yaml:"durationEncoder"`
+	EncodeCaller     CallerEncoder     `json:"callerEncoder" yaml:"callerEncoder"`
+	EncodeStacktrace StacktraceEncoder `json:"stacktraceEncoder" yaml:"stacktraceEncoder"`
 	// Unlike the other primitive type encoders, EncodeName is optional. The
 	// zero value falls back to FullNameEncoder.
 	EncodeName NameEncoder `json:"nameEncoder" yaml:"nameEncoder"`