README
¶
Meta Logger
This implements zap-based meta logger with buffering capability, allowing to merge multiple log records into one log line.
Usage
import "github.com/workato/engine-packages/log"
logLevel := "info"
oneLiner := false
logger, err := log.New(logLevel, oneLiner)
logger.Info("my message", log.String("dummy", "value"), log.Bool("noted", true))
One line logging
This mode is intended to decrease the load on log processing subsystems and help to reduce disk space requirements in case of intensive logging when you cannot just enable sampling, for system observability reasons.
With oneLiner == false the logger works just like a normal zap logger.
With oneLiner == true it aggregates log data in memory until logger.Flush() is called, then it outputs a single log record. Suppose we have the following calls:
logger.Info("loading", log.String("dummy", "foo"))
// ...
logger.Info("operation", log.String("status", "good"))
// ...
logger.Warn("system", log.Int("memory low", 33))
// ...
logger.Flush() // MUST EXPLICITLY FLUSH
If we set our logger to normal mode, like this:
logger, err := log.New("info", false) // normal mode
we will get 3 separate log records:
{ "level":"info", "time":"...", "msg":"loading", "dummy":"foo" }
{ "level":"info", "time":"...", "msg":"operation", "status":"good" }
{ "level":"warn", "time":"...", "msg":"system", "memory low":33 }
However, if we set our logger to "oneliner" mode, like this:
logger, err := log.New("info", true) // oneliner mode
we will get a single log record:
{ "level":"warn", "time":"...", "msg":"system", "dummy":"foo", "status":"good", "memory low":33 }
Note that the whole log record has "warn" type as it is the highest level of all.
Main message in oneliner mode
When merging multiple log records into a single one we need to set a message (msg field) for the whole record. Naturally you want it to be the most informative among all records, for example it may be the type of the endpoint currently working or something similar. If nothing is specified explicitly the first message of the highest level is used.
However, since we can switch oneliner mode on and off, we may want to explicitly mark the main message which should be selected amonth other messages of the same level. You may do it using MainMessage() method:
logger.Info("start request", log.String("connections", conns))
// ...
logger.Info("my operation", log.String("status", status), log.MainMessage()) // <--
// ...
logger.Info("stop request", log.Float("duration", dur), log.Int("items processed", nItems))
// ...
logger.Flush()
the result in oneliner mode will be:
{ "level":"info", "time":"...", "msg":"my operation", "connections": 20, "status":"good", "duration":"0.004", "items processed":6 }
In the normal mode we will just get three separate log lines without any extra fields.
Verbose (normal multi-line) mode
Sometimes the "oneliner" mode is not suitable for certain uses, like, for example, logging in multiple goroutines running in parallel. In this case there's a possibility of merging log records from different goroutines and the result log line can be messy. For such cases the Verbose() method is used which returns a normal multi-line logger, even if the logging has been initially switched to a one-line mode. So, you can have a "oneliner" logger for your request handler and "verbose" logger for background processes.
Documentation
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Index ¶
- type ContextMetaLoggerType
- type Field
- func Any(name string, val any) Field
- func Bool(key string, val bool) Field
- func Duration(key string, val time.Duration) Field
- func Error(err error) Field
- func Float64(key string, val float64) Field
- func Float64p(key string, val *float64) Field
- func Int(key string, val int) Field
- func Int64(key string, val int64) Field
- func MainMessage() Field
- func Stack(name string) Field
- func String(key string, val string) Field
- func Stringp(key string, val *string) Field
- func Strings(key string, val []string) Field
- func Time(key string, val time.Time) Field
- type FieldType
- type MetaLogger
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type ContextMetaLoggerType ¶
type ContextMetaLoggerType string
const (
ContextMetaLogger ContextMetaLoggerType = "ContextMetaLogger"
)
type Field ¶
type Field struct {
Key string
Type FieldType
Integer int64
Float64 float64
String string
Interface any
}
func MainMessage ¶
func MainMessage() Field
type MetaLogger ¶
type MetaLogger interface {
Debug(msg string, fields ...Field)
Info(msg string, fields ...Field)
Warn(msg string, fields ...Field)
Error(msg string, fields ...Field)
DPanic(msg string, fields ...Field)
Panic(msg string, fields ...Field)
Fatal(msg string, fields ...Field)
Infof(template string, args ...interface{})
Add(fields ...Field)
With(fields ...Field) MetaLogger
Sync() error
Flush()
Verbose() MetaLogger
SetContextLogger(ctx context.Context) context.Context
SlogHandler() slog.Handler
}
MetaLogger implements logging functionality
func GetContextLogger ¶
func GetContextLogger(ctx context.Context) MetaLogger
GetContextLogger returns a meta logger extracted from context.
Source Files