Logger

Log system for microservices.

The basic concept is create json formated logs what You can consume with logstash...

You can track Your logs flow with CorelationID, and TraceIDs
You can add fields
You can set up global level fileds
You can add tags
You can set up global level tags
You can add error stack

It has one concrete implementation with github.com/sirupsen/logrus but it is free to implement with other log systems.

CorelationID

It is a unique uuid for the entire flow across on the microservices network.

You can generate and add into the context.

If You make log .WithContext(ctx).Info("message"), the correlation Id will automatically extracted and added into the log.

TraceID

It is like the correlationID but in the flow it is changing and using linked list to shows the flow steps.

type TraceID struct {
	currentID string
	prevID    string
}

With traceID.NewStep() You can indicate the next step in Your process flow...

You can store TraceID also in the context traceID.SetToContext(ctx), and when You make make log with context .WithContext(ctx).Info("message") the it will automatically extracted and added into the log.

Logrus implementation

lgrs.MakeLoggerWithLogrus(logrusInstance) is the constructor for the logrus implementstion. If You pass nil paramter then it will create logrush instance by self.

Example use:


Log = lgrs.MakeLoggerWithLogrus(nil)
ctx := context.Background()
corelationID := logger.MakeCorelationID()
ctx = corelationID.SetToContext(ctx)
traceID := logger.MakeTraceID()
ctx = traceID.SetToContext(ctx)

Log.SetDefaultFields(logger.Fields{
  "Version": Version,
  "GitHash": GitHash,
  "AppPath": filepath.Dir(os.Args[0]),
  "AppBin":  filepath.Base(os.Args[0]),
})

Log.SetDefaultTags([]string{"apiserver", "orders"})

Log.WithContext(ctx).Info("App start")

...

traceID = traceID.NewStep()
ctx = traceID.SetToContext(ctx)

...
err := ...
err = errors.wrap(err,"MyCustom error msg")
Log.WithContext(ctx).WithError(err).Error("Error message")
...

Example output

[
  {
    "AppBin": "main",
    "AppPath": "/app",
    "CorelationID": "cf9ba76b-544d-4d40-8e94-cc62a4be941b",
    "GitHash": "fa2309",
    "TraceIDCurrent": "285cd6fb-43e1-4f9e-8ad8-df835421626e",
    "TraceIDPrev": "",
    "Version": "1",
    "level": "info",
    "msg": "App start",
    "tags": [
      "apiserver",
      "orders"
    ],
    "time": "2020-09-27T14:18:28+03:00"
  },
  {
    "AppBin": "main",
    "AppPath": "/app",
    "CorelationID": "cf9ba76b-544d-4d40-8e94-cc62a4be941b",
    "GitHash": "fa2309",
    "TraceIDCurrent": "004673de-ae55-41e3-be4e-50e790b2d00d",
    "TraceIDPrev": "285cd6fb-43e1-4f9e-8ad8-df835421626e",
    "Version": "1",
    "level": "info",
    "action": "order",
    "id": 15,
    "user": {
      "ID": 125,
      "Name": "Bob"
    },
    "items":["item1","item2"],
    "msg": "New request",
    "tags": [
      "apiserver",
      "orders"
      "order"
    ],
    "time": "2020-09-27T14:18:28+03:00"
  }
]

hobord / logger