zlog

What is a log tool I really want

I want to a log tool which provide help for reading through others codes, especially a big bounch of codes.

So the tool should like:

• It helps to show how the code runs
• Pretty showing key arguments
• Help to analyze data flow

And it should like below:

>>>> something is wrong                                         (app)[2018-07-09 18:07:57]
     - a=1
     - b=2
     - because the weather is not good
**** something is not working well                              (app/module1)[2018-07-09 18:07:57]
     - some one tole me the sun go  into cloud

---- This is normal output                                      (app/module2)[2018-07-09 18:07:57]
     {
       "a":1,
       "b":"abc",
     }

API Example

The simplest way to use zlog is simply the package-level exported logger:

package main

import (
  log "github.com/ssor/zlog"
)

func main() {
  log.WithFields(log.Fields{
    "animal": "walrus",
  }).Info("A walrus appears")
}

Note that it's completely api-compatible with the stdlib logger, so you can replace your log imports everywhere with log "github.com/ssor/zlog" and you'll now have the flexibility of Zlog. You can customize it all you want:

package main

import (
  "os"
  log "github.com/ssor/zlog"
)

func init() {
  // Output to stderr instead of stdout, could also be a file.
  log.SetOutput(os.Stderr)

  // Only log the warning severity or above.
  log.SetLevel(log.WarnLevel)
}

func main() {
  log.WithFields(log.Fields{
    "animal": "walrus",
    "size":   10,
  }).Info("A group of walrus emerges from the ocean")

  log.WithFields(log.Fields{
    "omg":    true,
    "number": 122,
  }).Warn("The group's number increased tremendously!")

  log.WithFields(log.Fields{
    "omg":    true,
    "number": 100,
  }).Fatal("The ice breaks!")

  // A common pattern is to re-use fields between logging statements by re-using
  contextLogger := log.WithFields(log.Fields{
    "common": "this is a common field",
    "other": "I also should be logged always",
  })

  contextLogger.Info("I'll be logged with common and other field")
  contextLogger.Info("Me too")
}

Fields

Zlog encourages careful, structured logging though logging fields instead of long, unparseable error messages. For example, instead of: log.Fatalf("Failed to send event %s to topic %s with key %d"), you should log the much more discoverable:

log.WithFields(log.Fields{
  "event": event,
  "topic": topic,
  "key": key,
}).Fatal("Failed to send event")

We've found this API forces you to think about logging in a way that produces much more useful logging messages. We've been in countless situations where just a single added field to a log statement that was already there would've saved us hours. The WithFields call is optional.