zap_marshaler

go-proto-zap-marshaler

A protoc plugin whitch generates MarshalLogObject() functions for each generated go structs to implement zapcore.ObjectMarshaler interface for uber-go/zap. So you can use zap.Object("proto", someProtoMessage) to log contents of the proto message.

Install

There are 2 protoc plugins to generate marshaler functions for zap:

• protoc-gen-zap-marshaler
  • which genearetes marshaler functions for all messages.
• protoc-gen-zap-marshaler-secure
  • which genearetes marshaler functions for all messages, but only logs fields enabled by proto option.

You can install those plugins by the following command:

$ go get github.com/kazegusuri/go-proto-zap-marshaler/protoc-gen-zap-marshaler
$ go get github.com/kazegusuri/go-proto-zap-marshaler/protoc-gen-zap-marshaler-secure

Usage

protoc-gen-zap-marshaler

To generate marshaler functions from proto, use --zap-marshaler_out with protoc command. That runs protoc-gen-zap-marshaler internally and then generates *.zap.go files.

$ protoc --zap-marshaler_out=. path/to/example.proto

protoc-gen-zap-marshaler-secure

This plugin generates marshaler functions as well as protoc-gen-zap-marshaler, but the funtions does not log anything as default. The marshaler only marshal fields enabled by zap_marshaler option.

To enable field option for message fields, you need to define proto like this:

message SimpleMessage {
  string string_value = 1 [(kazegusuri.zap_mashaler.field) = {enabled: true}];
  bool bool_value = 2 [(kazegusuri.zap_mashaler.field) = {enabled: true}];
}

To generate marshaler functions from proto, use --zap-marshaler-secure_out with protoc command. That runs protoc-gen-zap-marshaler-secure internally and then generates *.zap.go files.

$ protoc --zap-marshaler-secure_out=. path/to/example.proto

Field option

message ZapMarshalerRule {
    bool enabled = 1;
}

• enabled
  • The marshaler only logs a field whose value is true

Example

For this proto without field option, the secure plugin generates a go function:

syntax = "proto3";
package example;

message SimpleMessage {
  string string_value = 1;
  bool bool_value = 2;
}

func (m *SimpleMessage) MarshalLogObject(enc go_uber_org_zap_zapcore.ObjectEncoder) error {
	var keyName string
	_ = keyName

	return nil
}

The generated function does nothing.

By changing the proto with field option like this, the secure plugin generates a go function:

syntax = "proto3";
package example;

import "kazegusuri/go-prot-zap-marshaler/zap_marshaler.proto";

message SimpleMessage {
  string string_value = 1 [(kazegusuri.zap_mashaler.field) = {enabled: true}];
  bool bool_value = 2 [(kazegusuri.zap_mashaler.field) = {enabled: true}];
}

func (m *SimpleMessage) MarshalLogObject(enc go_uber_org_zap_zapcore.ObjectEncoder) error {
	var keyName string
	_ = keyName

	keyName = "string_value" // field string_value = 1
	enc.AddString(keyName, m.StringValue)

	keyName = "bool_value" // field bool_value = 2
	enc.AddBool(keyName, m.BoolValue)

	return nil
}