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+# Logrus <img src="http://i.imgur.com/hTeVwmJ.png" width="40" height="40" alt=":walrus:" class="emoji" title=":walrus:"/>&nbsp;[![Build Status](https://travis-ci.org/sirupsen/logrus.svg?branch=master)](https://travis-ci.org/sirupsen/logrus)&nbsp;[![GoDoc](https://godoc.org/github.com/sirupsen/logrus?status.svg)](https://godoc.org/github.com/sirupsen/logrus)
+
+Logrus is a structured logger for Go (golang), completely API compatible with
+the standard library logger.
+
+**Seeing weird case-sensitive problems?** It's in the past been possible to
+import Logrus as both upper- and lower-case. Due to the Go package environment,
+this caused issues in the community and we needed a standard. Some environments
+experienced problems with the upper-case variant, so the lower-case was decided.
+Everything using `logrus` will need to use the lower-case:
+`github.com/sirupsen/logrus`. Any package that isn't, should be changed.
+
+To fix Glide, see [these
+comments](https://github.com/sirupsen/logrus/issues/553#issuecomment-306591437).
+For an in-depth explanation of the casing issue, see [this
+comment](https://github.com/sirupsen/logrus/issues/570#issuecomment-313933276).
+
+**Are you interested in assisting in maintaining Logrus?** Currently I have a
+lot of obligations, and I am unable to provide Logrus with the maintainership it
+needs. If you'd like to help, please reach out to me at `simon at author's
+username dot com`.
+
+Nicely color-coded in development (when a TTY is attached, otherwise just
+plain text):
+
+![Colored](http://i.imgur.com/PY7qMwd.png)
+
+With `log.SetFormatter(&log.JSONFormatter{})`, for easy parsing by logstash
+or Splunk:
+
+```json
+{"animal":"walrus","level":"info","msg":"A group of walrus emerges from the
+ocean","size":10,"time":"2014-03-10 19:57:38.562264131 -0400 EDT"}
+
+{"level":"warning","msg":"The group's number increased tremendously!",
+"number":122,"omg":true,"time":"2014-03-10 19:57:38.562471297 -0400 EDT"}
+
+{"animal":"walrus","level":"info","msg":"A giant walrus appears!",
+"size":10,"time":"2014-03-10 19:57:38.562500591 -0400 EDT"}
+
+{"animal":"walrus","level":"info","msg":"Tremendously sized cow enters the ocean.",
+"size":9,"time":"2014-03-10 19:57:38.562527896 -0400 EDT"}
+
+{"level":"fatal","msg":"The ice breaks!","number":100,"omg":true,
+"time":"2014-03-10 19:57:38.562543128 -0400 EDT"}
+```
+
+With the default `log.SetFormatter(&log.TextFormatter{})` when a TTY is not
+attached, the output is compatible with the
+[logfmt](http://godoc.org/github.com/kr/logfmt) format:
+
+```text
+time="2015-03-26T01:27:38-04:00" level=debug msg="Started observing beach" animal=walrus number=8
+time="2015-03-26T01:27:38-04:00" level=info msg="A group of walrus emerges from the ocean" animal=walrus size=10
+time="2015-03-26T01:27:38-04:00" level=warning msg="The group's number increased tremendously!" number=122 omg=true
+time="2015-03-26T01:27:38-04:00" level=debug msg="Temperature changes" temperature=-4
+time="2015-03-26T01:27:38-04:00" level=panic msg="It's over 9000!" animal=orca size=9009
+time="2015-03-26T01:27:38-04:00" level=fatal msg="The ice breaks!" err=&{0x2082280c0 map[animal:orca size:9009] 2015-03-26 01:27:38.441574009 -0400 EDT panic It's over 9000!} number=100 omg=true
+exit status 1
+```
+
+#### Case-sensitivity
+
+The organization's name was changed to lower-case--and this will not be changed
+back. If you are getting import conflicts due to case sensitivity, please use
+the lower-case import: `github.com/sirupsen/logrus`.
+
+#### Example
+
+The simplest way to use Logrus is simply the package-level exported logger:
+
+```go
+package main
+
+import (
+  log "github.com/sirupsen/logrus"
+)
+
+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/sirupsen/logrus"`
+and you'll now have the flexibility of Logrus. You can customize it all you
+want:
+
+```go
+package main
+
+import (
+  "os"
+  log "github.com/sirupsen/logrus"
+)
+
+func init() {
+  // Log as JSON instead of the default ASCII formatter.
+  log.SetFormatter(&log.JSONFormatter{})
+
+  // Output to stdout instead of the default stderr
+  // Can be any io.Writer, see below for File example
+  log.SetOutput(os.Stdout)
+
+  // 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
+  // the logrus.Entry returned from WithFields()
+  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")
+}
+```
+
+For more advanced usage such as logging to multiple locations from the same
+application, you can also create an instance of the `logrus` Logger:
+
+```go
+package main
+
+import (
+  "os"
+  "github.com/sirupsen/logrus"
+)
+
+// Create a new instance of the logger. You can have any number of instances.
+var log = logrus.New()
+
+func main() {
+  // The API for setting attributes is a little different than the package level
+  // exported logger. See Godoc.
+  log.Out = os.Stdout
+
+  // You could set this to any `io.Writer` such as a file
+  // file, err := os.OpenFile("logrus.log", os.O_CREATE|os.O_WRONLY, 0666)
+  // if err == nil {
+  //  log.Out = file
+  // } else {
+  //  log.Info("Failed to log to file, using default stderr")
+  // }
+
+  log.WithFields(logrus.Fields{
+    "animal": "walrus",
+    "size":   10,
+  }).Info("A group of walrus emerges from the ocean")
+}
+```
+
+#### Fields
+
+Logrus encourages careful, structured logging through 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:
+
+```go
+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.
+
+In general, with Logrus using any of the `printf`-family functions should be
+seen as a hint you should add a field, however, you can still use the
+`printf`-family functions with Logrus.
+
+#### Default Fields
+
+Often it's helpful to have fields _always_ attached to log statements in an
+application or parts of one. For example, you may want to always log the
+`request_id` and `user_ip` in the context of a request. Instead of writing
+`log.WithFields(log.Fields{"request_id": request_id, "user_ip": user_ip})` on
+every line, you can create a `logrus.Entry` to pass around instead:
+
+```go
+requestLogger := log.WithFields(log.Fields{"request_id": request_id, "user_ip": user_ip})
+requestLogger.Info("something happened on that request") # will log request_id and user_ip
+requestLogger.Warn("something not great happened")
+```
+
+#### Hooks
+
+You can add hooks for logging levels. For example to send errors to an exception
+tracking service on `Error`, `Fatal` and `Panic`, info to StatsD or log to
+multiple places simultaneously, e.g. syslog.
+
+Logrus comes with [built-in hooks](hooks/). Add those, or your custom hook, in
+`init`:
+
+```go
+import (
+  log "github.com/sirupsen/logrus"
+  "gopkg.in/gemnasium/logrus-airbrake-hook.v2" // the package is named "airbrake"
+  logrus_syslog "github.com/sirupsen/logrus/hooks/syslog"
+  "log/syslog"
+)
+
+func init() {
+
+  // Use the Airbrake hook to report errors that have Error severity or above to
+  // an exception tracker. You can create custom hooks, see the Hooks section.
+  log.AddHook(airbrake.NewHook(123, "xyz", "production"))
+
+  hook, err := logrus_syslog.NewSyslogHook("udp", "localhost:514", syslog.LOG_INFO, "")
+  if err != nil {
+    log.Error("Unable to connect to local syslog daemon")
+  } else {
+    log.AddHook(hook)
+  }
+}
+```
+Note: Syslog hook also support connecting to local syslog (Ex. "/dev/log" or "/var/run/syslog" or "/var/run/log"). For the detail, please check the [syslog hook README](hooks/syslog/README.md).
+
+| Hook  | Description |
+| ----- | ----------- |
+| [Airbrake "legacy"](https://github.com/gemnasium/logrus-airbrake-legacy-hook) | Send errors to an exception tracking service compatible with the Airbrake API V2. Uses [`airbrake-go`](https://github.com/tobi/airbrake-go) behind the scenes. |
+| [Airbrake](https://github.com/gemnasium/logrus-airbrake-hook) | Send errors to the Airbrake API V3. Uses the official [`gobrake`](https://github.com/airbrake/gobrake) behind the scenes. |
+| [Amazon Kinesis](https://github.com/evalphobia/logrus_kinesis) | Hook for logging to [Amazon Kinesis](https://aws.amazon.com/kinesis/) |
+| [Amqp-Hook](https://github.com/vladoatanasov/logrus_amqp) | Hook for logging to Amqp broker (Like RabbitMQ) |
+| [Application Insights](https://github.com/jjcollinge/logrus-appinsights) | Hook for logging to [Application Insights](https://azure.microsoft.com/en-us/services/application-insights/)
+| [AzureTableHook](https://github.com/kpfaulkner/azuretablehook/) | Hook for logging to Azure Table Storage|
+| [Bugsnag](https://github.com/Shopify/logrus-bugsnag/blob/master/bugsnag.go) | Send errors to the Bugsnag exception tracking service. |
+| [DeferPanic](https://github.com/deferpanic/dp-logrus) | Hook for logging to DeferPanic |
+| [Discordrus](https://github.com/kz/discordrus) | Hook for logging to [Discord](https://discordapp.com/) |
+| [ElasticSearch](https://github.com/sohlich/elogrus) | Hook for logging to ElasticSearch|
+| [Firehose](https://github.com/beaubrewer/logrus_firehose) | Hook for logging to [Amazon Firehose](https://aws.amazon.com/kinesis/firehose/)
+| [Fluentd](https://github.com/evalphobia/logrus_fluent) | Hook for logging to fluentd |
+| [Go-Slack](https://github.com/multiplay/go-slack) | Hook for logging to [Slack](https://slack.com) |
+| [Graylog](https://github.com/gemnasium/logrus-graylog-hook) | Hook for logging to [Graylog](http://graylog2.org/) |
+| [Hiprus](https://github.com/nubo/hiprus) | Send errors to a channel in hipchat. |
+| [Honeybadger](https://github.com/agonzalezro/logrus_honeybadger) | Hook for sending exceptions to Honeybadger |
+| [InfluxDB](https://github.com/Abramovic/logrus_influxdb) | Hook for logging to influxdb |
+| [Influxus](http://github.com/vlad-doru/influxus) | Hook for concurrently logging to [InfluxDB](http://influxdata.com/) |
+| [Journalhook](https://github.com/wercker/journalhook) | Hook for logging to `systemd-journald` |
+| [KafkaLogrus](https://github.com/tracer0tong/kafkalogrus) | Hook for logging to Kafka |
+| [LFShook](https://github.com/rifflock/lfshook) | Hook for logging to the local filesystem |
+| [Logbeat](https://github.com/macandmia/logbeat) | Hook for logging to [Opbeat](https://opbeat.com/) |
+| [Logentries](https://github.com/jcftang/logentriesrus) | Hook for logging to [Logentries](https://logentries.com/) |
+| [Logentrus](https://github.com/puddingfactory/logentrus) | Hook for logging to [Logentries](https://logentries.com/) |
+| [Logmatic.io](https://github.com/logmatic/logmatic-go) | Hook for logging to [Logmatic.io](http://logmatic.io/) |
+| [Logrusly](https://github.com/sebest/logrusly) | Send logs to [Loggly](https://www.loggly.com/) |
+| [Logstash](https://github.com/bshuster-repo/logrus-logstash-hook) | Hook for logging to [Logstash](https://www.elastic.co/products/logstash) |
+| [Mail](https://github.com/zbindenren/logrus_mail) | Hook for sending exceptions via mail |
+| [Mattermost](https://github.com/shuLhan/mattermost-integration/tree/master/hooks/logrus) | Hook for logging to [Mattermost](https://mattermost.com/) |
+| [Mongodb](https://github.com/weekface/mgorus) | Hook for logging to mongodb |
+| [NATS-Hook](https://github.com/rybit/nats_logrus_hook) | Hook for logging to [NATS](https://nats.io) |
+| [Octokit](https://github.com/dorajistyle/logrus-octokit-hook) | Hook for logging to github via octokit |
+| [Papertrail](https://github.com/polds/logrus-papertrail-hook) | Send errors to the [Papertrail](https://papertrailapp.com) hosted logging service via UDP. |
+| [PostgreSQL](https://github.com/gemnasium/logrus-postgresql-hook) | Send logs to [PostgreSQL](http://postgresql.org) |
+| [Promrus](https://github.com/weaveworks/promrus) | Expose number of log messages as [Prometheus](https://prometheus.io/) metrics |
+| [Pushover](https://github.com/toorop/logrus_pushover) | Send error via [Pushover](https://pushover.net) |
+| [Raygun](https://github.com/squirkle/logrus-raygun-hook) | Hook for logging to [Raygun.io](http://raygun.io/) |
+| [Redis-Hook](https://github.com/rogierlommers/logrus-redis-hook) | Hook for logging to a ELK stack (through Redis) |
+| [Rollrus](https://github.com/heroku/rollrus) | Hook for sending errors to rollbar |
+| [Scribe](https://github.com/sagar8192/logrus-scribe-hook) | Hook for logging to [Scribe](https://github.com/facebookarchive/scribe)|
+| [Sentry](https://github.com/evalphobia/logrus_sentry) | Send errors to the Sentry error logging and aggregation service. |
+| [Slackrus](https://github.com/johntdyer/slackrus) | Hook for Slack chat. |
+| [Stackdriver](https://github.com/knq/sdhook) | Hook for logging to [Google Stackdriver](https://cloud.google.com/logging/) |
+| [Sumorus](https://github.com/doublefree/sumorus) | Hook for logging to [SumoLogic](https://www.sumologic.com/)|
+| [Syslog](https://github.com/sirupsen/logrus/blob/master/hooks/syslog/syslog.go) | Send errors to remote syslog server. Uses standard library `log/syslog` behind the scenes. |
+| [Syslog TLS](https://github.com/shinji62/logrus-syslog-ng) | Send errors to remote syslog server with TLS support. |
+| [Telegram](https://github.com/rossmcdonald/telegram_hook) | Hook for logging errors to [Telegram](https://telegram.org/) |
+| [TraceView](https://github.com/evalphobia/logrus_appneta) | Hook for logging to [AppNeta TraceView](https://www.appneta.com/products/traceview/) |
+| [Typetalk](https://github.com/dragon3/logrus-typetalk-hook) | Hook for logging to [Typetalk](https://www.typetalk.in/) |
+| [logz.io](https://github.com/ripcurld00d/logrus-logzio-hook) | Hook for logging to [logz.io](https://logz.io), a Log as a Service using Logstash |
+| [SQS-Hook](https://github.com/tsarpaul/logrus_sqs) | Hook for logging to [Amazon Simple Queue Service (SQS)](https://aws.amazon.com/sqs/) |
+
+#### Level logging
+
+Logrus has six logging levels: Debug, Info, Warning, Error, Fatal and Panic.
+
+```go
+log.Debug("Useful debugging information.")
+log.Info("Something noteworthy happened!")
+log.Warn("You should probably take a look at this.")
+log.Error("Something failed but I'm not quitting.")
+// Calls os.Exit(1) after logging
+log.Fatal("Bye.")
+// Calls panic() after logging
+log.Panic("I'm bailing.")
+```
+
+You can set the logging level on a `Logger`, then it will only log entries with
+that severity or anything above it:
+
+```go
+// Will log anything that is info or above (warn, error, fatal, panic). Default.
+log.SetLevel(log.InfoLevel)
+```
+
+It may be useful to set `log.Level = logrus.DebugLevel` in a debug or verbose
+environment if your application has that.
+
+#### Entries
+
+Besides the fields added with `WithField` or `WithFields` some fields are
+automatically added to all logging events:
+
+1. `time`. The timestamp when the entry was created.
+2. `msg`. The logging message passed to `{Info,Warn,Error,Fatal,Panic}` after
+   the `AddFields` call. E.g. `Failed to send event.`
+3. `level`. The logging level. E.g. `info`.
+
+#### Environments
+
+Logrus has no notion of environment.
+
+If you wish for hooks and formatters to only be used in specific environments,
+you should handle that yourself. For example, if your application has a global
+variable `Environment`, which is a string representation of the environment you
+could do:
+
+```go
+import (
+  log "github.com/sirupsen/logrus"
+)
+
+init() {
+  // do something here to set environment depending on an environment variable
+  // or command-line flag
+  if Environment == "production" {
+    log.SetFormatter(&log.JSONFormatter{})
+  } else {
+    // The TextFormatter is default, you don't actually have to do this.
+    log.SetFormatter(&log.TextFormatter{})
+  }
+}
+```
+
+This configuration is how `logrus` was intended to be used, but JSON in
+production is mostly only useful if you do log aggregation with tools like
+Splunk or Logstash.
+
+#### Formatters
+
+The built-in logging formatters are:
+
+* `logrus.TextFormatter`. Logs the event in colors if stdout is a tty, otherwise
+  without colors.
+  * *Note:* to force colored output when there is no TTY, set the `ForceColors`
+    field to `true`.  To force no colored output even if there is a TTY  set the
+    `DisableColors` field to `true`. For Windows, see
+    [github.com/mattn/go-colorable](https://github.com/mattn/go-colorable).
+  * All options are listed in the [generated docs](https://godoc.org/github.com/sirupsen/logrus#TextFormatter).
+* `logrus.JSONFormatter`. Logs fields as JSON.
+  * All options are listed in the [generated docs](https://godoc.org/github.com/sirupsen/logrus#JSONFormatter).
+
+Third party logging formatters:
+
+* [`FluentdFormatter`](https://github.com/joonix/log). Formats entries that can be parsed by Kubernetes and Google Container Engine.
+* [`logstash`](https://github.com/bshuster-repo/logrus-logstash-hook). Logs fields as [Logstash](http://logstash.net) Events.
+* [`prefixed`](https://github.com/x-cray/logrus-prefixed-formatter). Displays log entry source along with alternative layout.
+* [`zalgo`](https://github.com/aybabtme/logzalgo). Invoking the P͉̫o̳̼̊w̖͈̰͎e̬͔̭͂r͚̼̹̲ ̫͓͉̳͈ō̠͕͖̚f̝͍̠ ͕̲̞͖͑Z̖̫̤̫ͪa͉̬͈̗l͖͎g̳̥o̰̥̅!̣͔̲̻͊̄ ̙̘̦̹̦.
+
+You can define your formatter by implementing the `Formatter` interface,
+requiring a `Format` method. `Format` takes an `*Entry`. `entry.Data` is a
+`Fields` type (`map[string]interface{}`) with all your fields as well as the
+default ones (see Entries section above):
+
+```go
+type MyJSONFormatter struct {
+}
+
+log.SetFormatter(new(MyJSONFormatter))
+
+func (f *MyJSONFormatter) Format(entry *Entry) ([]byte, error) {
+  // Note this doesn't include Time, Level and Message which are available on
+  // the Entry. Consult `godoc` on information about those fields or read the
+  // source of the official loggers.
+  serialized, err := json.Marshal(entry.Data)
+    if err != nil {
+      return nil, fmt.Errorf("Failed to marshal fields to JSON, %v", err)
+    }
+  return append(serialized, '\n'), nil
+}
+```
+
+#### Logger as an `io.Writer`
+
+Logrus can be transformed into an `io.Writer`. That writer is the end of an `io.Pipe` and it is your responsibility to close it.
+
+```go
+w := logger.Writer()
+defer w.Close()
+
+srv := http.Server{
+    // create a stdlib log.Logger that writes to
+    // logrus.Logger.
+    ErrorLog: log.New(w, "", 0),
+}
+```
+
+Each line written to that writer will be printed the usual way, using formatters
+and hooks. The level for those entries is `info`.
+
+This means that we can override the standard library logger easily:
+
+```go
+logger := logrus.New()
+logger.Formatter = &logrus.JSONFormatter{}
+
+// Use logrus for standard log output
+// Note that `log` here references stdlib's log
+// Not logrus imported under the name `log`.
+log.SetOutput(logger.Writer())
+```
+
+#### Rotation
+
+Log rotation is not provided with Logrus. Log rotation should be done by an
+external program (like `logrotate(8)`) that can compress and delete old log
+entries. It should not be a feature of the application-level logger.
+
+#### Tools
+
+| Tool | Description |
+| ---- | ----------- |
+|[Logrus Mate](https://github.com/gogap/logrus_mate)|Logrus mate is a tool for Logrus to manage loggers, you can initial logger's level, hook and formatter by config file, the logger will generated with different config at different environment.|
+|[Logrus Viper Helper](https://github.com/heirko/go-contrib/tree/master/logrusHelper)|An Helper around Logrus to wrap with spf13/Viper to load configuration with fangs! And to simplify Logrus configuration use some behavior of [Logrus Mate](https://github.com/gogap/logrus_mate). [sample](https://github.com/heirko/iris-contrib/blob/master/middleware/logrus-logger/example) |
+
+#### Testing
+
+Logrus has a built in facility for asserting the presence of log messages. This is implemented through the `test` hook and provides:
+
+* decorators for existing logger (`test.NewLocal` and `test.NewGlobal`) which basically just add the `test` hook
+* a test logger (`test.NewNullLogger`) that just records log messages (and does not output any):
+
+```go
+import(
+  "github.com/sirupsen/logrus"
+  "github.com/sirupsen/logrus/hooks/test"
+  "github.com/stretchr/testify/assert"
+  "testing"
+)
+
+func TestSomething(t*testing.T){
+  logger, hook := test.NewNullLogger()
+  logger.Error("Helloerror")
+
+  assert.Equal(t, 1, len(hook.Entries))
+  assert.Equal(t, logrus.ErrorLevel, hook.LastEntry().Level)
+  assert.Equal(t, "Helloerror", hook.LastEntry().Message)
+
+  hook.Reset()
+  assert.Nil(t, hook.LastEntry())
+}
+```
+
+#### Fatal handlers
+
+Logrus can register one or more functions that will be called when any `fatal`
+level message is logged. The registered handlers will be executed before
+logrus performs a `os.Exit(1)`. This behavior may be helpful if callers need
+to gracefully shutdown. Unlike a `panic("Something went wrong...")` call which can be intercepted with a deferred `recover` a call to `os.Exit(1)` can not be intercepted.
+
+```
+...
+handler := func() {
+  // gracefully shutdown something...
+}
+logrus.RegisterExitHandler(handler)
+...
+```
+
+#### Thread safety
+
+By default Logger is protected by mutex for concurrent writes, this mutex is invoked when calling hooks and writing logs.
+If you are sure such locking is not needed, you can call logger.SetNoLock() to disable the locking.
+
+Situation when locking is not needed includes:
+
+* You have no hooks registered, or hooks calling is already thread-safe.
+
+* Writing to logger.Out is already thread-safe, for example:
+
+  1) logger.Out is protected by locks.
+
+  2) logger.Out is a os.File handler opened with `O_APPEND` flag, and every write is smaller than 4k. (This allow multi-thread/multi-process writing)
+
+     (Refer to http://www.notthewizard.com/2014/06/17/are-files-appends-really-atomic/)