github.com/metacubex/gvisor@v0.0.0-20240320004321-933faba989ec/pkg/log/json.go (about)

     1  // Copyright 2018 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package log
    16  
    17  import (
    18  	"encoding/json"
    19  	"fmt"
    20  	"runtime"
    21  	"strings"
    22  	"time"
    23  )
    24  
    25  type jsonLog struct {
    26  	Msg   string    `json:"msg"`
    27  	Level Level     `json:"level"`
    28  	Time  time.Time `json:"time"`
    29  }
    30  
    31  // MarshalJSON implements json.Marshaler.MarashalJSON.
    32  func (l Level) MarshalJSON() ([]byte, error) {
    33  	switch l {
    34  	case Warning:
    35  		return []byte(`"warning"`), nil
    36  	case Info:
    37  		return []byte(`"info"`), nil
    38  	case Debug:
    39  		return []byte(`"debug"`), nil
    40  	default:
    41  		return nil, fmt.Errorf("unknown level %v", l)
    42  	}
    43  }
    44  
    45  // UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON.  It can unmarshal
    46  // from both string names and integers.
    47  func (l *Level) UnmarshalJSON(b []byte) error {
    48  	switch s := string(b); s {
    49  	case "0", `"warning"`:
    50  		*l = Warning
    51  	case "1", `"info"`:
    52  		*l = Info
    53  	case "2", `"debug"`:
    54  		*l = Debug
    55  	default:
    56  		return fmt.Errorf("unknown level %q", s)
    57  	}
    58  	return nil
    59  }
    60  
    61  // JSONEmitter logs messages in json format.
    62  type JSONEmitter struct {
    63  	*Writer
    64  }
    65  
    66  // Emit implements Emitter.Emit.
    67  func (e JSONEmitter) Emit(depth int, level Level, timestamp time.Time, format string, v ...any) {
    68  	logLine := fmt.Sprintf(format, v...)
    69  	if _, file, line, ok := runtime.Caller(depth + 1); ok {
    70  		if slash := strings.LastIndexByte(file, byte('/')); slash >= 0 {
    71  			file = file[slash+1:] // Trim any directory path from the file.
    72  		}
    73  		logLine = fmt.Sprintf("%s:%d] %s", file, line, logLine)
    74  	}
    75  	j := jsonLog{
    76  		Msg:   logLine,
    77  		Level: level,
    78  		Time:  timestamp,
    79  	}
    80  	b, err := json.Marshal(j)
    81  	if err != nil {
    82  		panic(err)
    83  	}
    84  	e.Writer.Write(b)
    85  }