#142 Add structured JSON logger and associated tests

This commit introduces a new type 'JSONlog' that satisfies the Logger interface for structured JSON logging. This includes new methods 'Debugf', 'Infof', 'Warnf' and 'Errorf' to log messages at different levels and an associated test 'jsonlog_test.go' to ensure correct functionality. This enhances the logging functionality by providing clarity in logs and eases debugging process.
This commit is contained in:
Winni Neessen 2023-08-23 11:16:23 +02:00
parent 0189acf1e4
commit 77d9e3d02a
Signed by: wneessen
GPG key ID: 385AC9889632126E
3 changed files with 406 additions and 0 deletions

82
log/jsonlog.go Normal file
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@ -0,0 +1,82 @@
// SPDX-FileCopyrightText: Copyright (c) 2023 The go-mail Authors
//
// SPDX-License-Identifier: MIT
//go:build go1.21
// +build go1.21
package log
import (
"fmt"
"io"
"log/slog"
)
// JSONlog is the default structured JSON logger that satisfies the Logger interface
type JSONlog struct {
l Level
log *slog.Logger
}
// NewJSON returns a new JSONlog type that satisfies the Logger interface
func NewJSON(o io.Writer, l Level) *JSONlog {
lo := slog.HandlerOptions{}
switch l {
case LevelDebug:
lo.Level = slog.LevelDebug
case LevelInfo:
lo.Level = slog.LevelInfo
case LevelWarn:
lo.Level = slog.LevelWarn
case LevelError:
lo.Level = slog.LevelError
default:
lo.Level = slog.LevelDebug
}
lh := slog.NewJSONHandler(o, &lo)
return &JSONlog{
l: l,
log: slog.New(lh),
}
}
// Debugf logs a debug message via the structured JSON logger
func (l *JSONlog) Debugf(lo Log) {
if l.l >= LevelDebug {
l.log.WithGroup(DirString).With(
slog.String(DirFromString, lo.directionFrom()),
slog.String(DirToString, lo.directionTo()),
).Debug(fmt.Sprintf(lo.Format, lo.Messages...))
}
}
// Infof logs a info message via the structured JSON logger
func (l *JSONlog) Infof(lo Log) {
if l.l >= LevelInfo {
l.log.WithGroup(DirString).With(
slog.String(DirFromString, lo.directionFrom()),
slog.String(DirToString, lo.directionTo()),
).Info(fmt.Sprintf(lo.Format, lo.Messages...))
}
}
// Warnf logs a warn message via the structured JSON logger
func (l *JSONlog) Warnf(lo Log) {
if l.l >= LevelWarn {
l.log.WithGroup(DirString).With(
slog.String(DirFromString, lo.directionFrom()),
slog.String(DirToString, lo.directionTo()),
).Warn(fmt.Sprintf(lo.Format, lo.Messages...))
}
}
// Errorf logs a warn message via the structured JSON logger
func (l *JSONlog) Errorf(lo Log) {
if l.l >= LevelError {
l.log.WithGroup(DirString).With(
slog.String(DirFromString, lo.directionFrom()),
slog.String(DirToString, lo.directionTo()),
).Error(fmt.Sprintf(lo.Format, lo.Messages...))
}
}

297
log/jsonlog_test.go Normal file
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@ -0,0 +1,297 @@
// SPDX-FileCopyrightText: Copyright (c) 2023 The go-mail Authors
//
// SPDX-License-Identifier: MIT
//go:build go1.21
// +build go1.21
package log
import (
"bytes"
"encoding/json"
"fmt"
"testing"
"time"
)
type jsonLog struct {
Direction jsonDir `json:"direction"`
Level string `json:"level"`
Message string `json:"msg"`
Time time.Time `json:"time"`
}
type jsonDir struct {
From string `json:"from"`
To string `json:"to"`
}
func TestNewJSON(t *testing.T) {
var b bytes.Buffer
l := NewJSON(&b, LevelDebug)
if l.l != LevelDebug {
t.Error("Expected level to be LevelDebug, got ", l.l)
}
if l.log == nil {
t.Error("logger not initialized")
}
}
func TestJSONDebugf(t *testing.T) {
var b bytes.Buffer
l := NewJSON(&b, LevelDebug)
f := "test %s"
msg := "foo"
msg2 := "bar"
l.Debugf(Log{Direction: DirServerToClient, Format: f, Messages: []interface{}{msg}})
exFrom := "server"
exTo := "client"
jl, err := unmarshalLog(b.Bytes())
if err != nil {
t.Errorf("Debugf() failed, unmarshal json log message failed: %s", err)
}
if jl.Direction.To != exTo {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exTo, jl.Direction.To)
}
if jl.Direction.From != exFrom {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exFrom, jl.Direction.From)
}
if jl.Message != fmt.Sprintf(f, msg) {
t.Errorf("Debugf() failed, expected message: %s, got %s", msg, jl.Message)
}
b.Reset()
l.Debugf(Log{Direction: DirClientToServer, Format: f, Messages: []interface{}{msg2}})
exFrom = "client"
exTo = "server"
jl, err = unmarshalLog(b.Bytes())
if err != nil {
t.Errorf("Debugf() failed, unmarshal json log message failed: %s", err)
}
if jl.Direction.To != exTo {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exTo, jl.Direction.To)
}
if jl.Direction.From != exFrom {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exFrom, jl.Direction.From)
}
if jl.Message != fmt.Sprintf(f, msg2) {
t.Errorf("Debugf() failed, expected message: %s, got %s", msg2, jl.Message)
}
b.Reset()
l.l = LevelInfo
l.Debugf(Log{Direction: DirServerToClient, Format: "test %s", Messages: []interface{}{"foo"}})
if b.String() != "" {
t.Error("Debug message was not expected to be logged")
}
}
func TestJSONDebugf_WithDefault(t *testing.T) {
var b bytes.Buffer
l := NewJSON(&b, 999)
f := "test %s"
msg := "foo"
msg2 := "bar"
l.Debugf(Log{Direction: DirServerToClient, Format: f, Messages: []interface{}{msg}})
exFrom := "server"
exTo := "client"
jl, err := unmarshalLog(b.Bytes())
if err != nil {
t.Errorf("Debugf() failed, unmarshal json log message failed: %s", err)
}
if jl.Direction.To != exTo {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exTo, jl.Direction.To)
}
if jl.Direction.From != exFrom {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exFrom, jl.Direction.From)
}
if jl.Message != fmt.Sprintf(f, msg) {
t.Errorf("Debugf() failed, expected message: %s, got %s", msg, jl.Message)
}
b.Reset()
l.Debugf(Log{Direction: DirClientToServer, Format: f, Messages: []interface{}{msg2}})
exFrom = "client"
exTo = "server"
jl, err = unmarshalLog(b.Bytes())
if err != nil {
t.Errorf("Debugf() failed, unmarshal json log message failed: %s", err)
}
if jl.Direction.To != exTo {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exTo, jl.Direction.To)
}
if jl.Direction.From != exFrom {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exFrom, jl.Direction.From)
}
if jl.Message != fmt.Sprintf(f, msg2) {
t.Errorf("Debugf() failed, expected message: %s, got %s", msg2, jl.Message)
}
b.Reset()
l.l = LevelInfo
l.Debugf(Log{Direction: DirServerToClient, Format: "test %s", Messages: []interface{}{"foo"}})
if b.String() != "" {
t.Error("Debug message was not expected to be logged")
}
}
func TestJSONInfof(t *testing.T) {
var b bytes.Buffer
l := NewJSON(&b, LevelInfo)
f := "test %s"
msg := "foo"
msg2 := "bar"
l.Infof(Log{Direction: DirServerToClient, Format: f, Messages: []interface{}{msg}})
exFrom := "server"
exTo := "client"
jl, err := unmarshalLog(b.Bytes())
if err != nil {
t.Errorf("Debugf() failed, unmarshal json log message failed: %s", err)
}
if jl.Direction.To != exTo {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exTo, jl.Direction.To)
}
if jl.Direction.From != exFrom {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exFrom, jl.Direction.From)
}
if jl.Message != fmt.Sprintf(f, msg) {
t.Errorf("Debugf() failed, expected message: %s, got %s", msg, jl.Message)
}
b.Reset()
l.Infof(Log{Direction: DirClientToServer, Format: f, Messages: []interface{}{msg2}})
exFrom = "client"
exTo = "server"
jl, err = unmarshalLog(b.Bytes())
if err != nil {
t.Errorf("Debugf() failed, unmarshal json log message failed: %s", err)
}
if jl.Direction.To != exTo {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exTo, jl.Direction.To)
}
if jl.Direction.From != exFrom {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exFrom, jl.Direction.From)
}
if jl.Message != fmt.Sprintf(f, msg2) {
t.Errorf("Debugf() failed, expected message: %s, got %s", msg2, jl.Message)
}
b.Reset()
l.l = LevelWarn
l.Infof(Log{Direction: DirServerToClient, Format: "test %s", Messages: []interface{}{"foo"}})
if b.String() != "" {
t.Error("Info message was not expected to be logged")
}
}
func TestJSONWarnf(t *testing.T) {
var b bytes.Buffer
l := NewJSON(&b, LevelWarn)
f := "test %s"
msg := "foo"
msg2 := "bar"
l.Warnf(Log{Direction: DirServerToClient, Format: f, Messages: []interface{}{msg}})
exFrom := "server"
exTo := "client"
jl, err := unmarshalLog(b.Bytes())
if err != nil {
t.Errorf("Debugf() failed, unmarshal json log message failed: %s", err)
}
if jl.Direction.To != exTo {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exTo, jl.Direction.To)
}
if jl.Direction.From != exFrom {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exFrom, jl.Direction.From)
}
if jl.Message != fmt.Sprintf(f, msg) {
t.Errorf("Debugf() failed, expected message: %s, got %s", msg, jl.Message)
}
b.Reset()
l.Warnf(Log{Direction: DirClientToServer, Format: f, Messages: []interface{}{msg2}})
exFrom = "client"
exTo = "server"
jl, err = unmarshalLog(b.Bytes())
if err != nil {
t.Errorf("Debugf() failed, unmarshal json log message failed: %s", err)
}
if jl.Direction.To != exTo {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exTo, jl.Direction.To)
}
if jl.Direction.From != exFrom {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exFrom, jl.Direction.From)
}
if jl.Message != fmt.Sprintf(f, msg2) {
t.Errorf("Debugf() failed, expected message: %s, got %s", msg2, jl.Message)
}
b.Reset()
l.l = LevelError
l.Warnf(Log{Direction: DirServerToClient, Format: "test %s", Messages: []interface{}{"foo"}})
if b.String() != "" {
t.Error("Warn message was not expected to be logged")
}
}
func TestJSONErrorf(t *testing.T) {
var b bytes.Buffer
l := NewJSON(&b, LevelError)
f := "test %s"
msg := "foo"
msg2 := "bar"
l.Errorf(Log{Direction: DirServerToClient, Format: f, Messages: []interface{}{msg}})
exFrom := "server"
exTo := "client"
jl, err := unmarshalLog(b.Bytes())
if err != nil {
t.Errorf("Debugf() failed, unmarshal json log message failed: %s", err)
}
if jl.Direction.To != exTo {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exTo, jl.Direction.To)
}
if jl.Direction.From != exFrom {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exFrom, jl.Direction.From)
}
if jl.Message != fmt.Sprintf(f, msg) {
t.Errorf("Debugf() failed, expected message: %s, got %s", msg, jl.Message)
}
b.Reset()
l.Errorf(Log{Direction: DirClientToServer, Format: f, Messages: []interface{}{msg2}})
exFrom = "client"
exTo = "server"
jl, err = unmarshalLog(b.Bytes())
if err != nil {
t.Errorf("Debugf() failed, unmarshal json log message failed: %s", err)
}
if jl.Direction.To != exTo {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exTo, jl.Direction.To)
}
if jl.Direction.From != exFrom {
t.Errorf("Debugf() failed, expected message to: %s, got: %s", exFrom, jl.Direction.From)
}
if jl.Message != fmt.Sprintf(f, msg2) {
t.Errorf("Debugf() failed, expected message: %s, got %s", msg2, jl.Message)
}
b.Reset()
l.l = -99
l.Errorf(Log{Direction: DirServerToClient, Format: "test %s", Messages: []interface{}{"foo"}})
if b.String() != "" {
t.Error("Error message was not expected to be logged")
}
}
func unmarshalLog(j []byte) (jsonLog, error) {
var jl jsonLog
if err := json.Unmarshal(j, &jl); err != nil {
return jl, err
}
return jl, nil
}

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@ -21,6 +21,15 @@ const (
LevelDebug
)
const (
// DirString is a constant used for the structured logger
DirString = "direction"
// DirFromString is a constant used for the structured logger
DirFromString = "from"
// DirToString is a constant used for the structured logger
DirToString = "to"
)
// Direction is a type wrapper for the direction a debug log message goes
type Direction int
@ -51,3 +60,21 @@ func (l Log) directionPrefix() string {
}
return p
}
// directionFrom will return a from direction string depending on the Direction.
func (l Log) directionFrom() string {
p := "server"
if l.Direction == DirClientToServer {
p = "client"
}
return p
}
// directionTo will return a to direction string depending on the Direction.
func (l Log) directionTo() string {
p := "client"
if l.Direction == DirClientToServer {
p = "server"
}
return p
}