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Go log Collection

To send your go logs to Datadog, we recommend logging to a file and then tailing that file with your Datadog Agent. To achieve that we suggest the following setup with the open source logging library called logrus

We strongly encourage setting up your logging library to produce your logs in JSON format to avoid the need for custom parsing rules.

Configure your logger

For a classic Go configuration, open a main.go file and paste the following code:

package main

import (
  log "github.com/Sirupsen/logrus"
)

func main() {

    // use JSONFormatter
    log.SetFormatter(&log.JSONFormatter{})

    // log an event as usual with logrus
    log.WithFields(log.Fields{"string": "foo", "int": 1, "float": 1.1 }).Info("My first event from golang to stdout")
}

It’s very easy to add metas to any log if you provide a JSON object that you want to see in the log event.

These metas can be hostname, username, customers, metric or any information that help you troubleshoot and understand what happens in your Go application.

package main

import (
  log "github.com/Sirupsen/logrus"
)

func main() {

    // use JSONFormatter
    log.SetFormatter(&log.JSONFormatter{})

    // log an event as usual with logrus
    log.WithFields(log.Fields{"string": "foo", "int": 1, "float": 1.1 }).Info("My first event from golang to stdout")
  // For metadata, a common pattern is to re-use fields between logging statements  by re-using
  contextualizedLog := log.WithFields(log.Fields{
    "hostname": "staging-1",
    "appname": "foo-app",
    "session": "1ce3f6v"
  })

  contextualizedLog.Info("Simple event with global metadata")
  
}

Configure your Datadog Agent

Create a go.d/conf.yaml file in your conf.d/ folder with the following content:

##Log section
logs:

    # - type : (mandatory) type of log input source (tcp / udp / file)
    #   port / path : (mandatory) Set port if type is tcp or udp. Set path if type is file
    #   service : (mandatory) name of the service owning the log
    #   source : (mandatory) attribute that defines which integration is sending the logs
    #   sourcecategory : (optional) Multiple value attribute. Can be used to refine the source attribtue
    #   tags: (optional) add tags to each logs collected

  - type: file
    path: /path/to/your/go/log.log
    service: go
    source: go
    sourcecategory: sourcecode

Getting Further

Here are some little advices:

  • Always give a name to the logger corresponding to the functionality or service you try to deliver.
  • Log a lot in the DEBUG level and log accurately in the INFO, WARNING and FATAL levels; since these are the log levels you’ll get in your production environments.
  • Start small and try to log the important stuff first, instead of being comprehensive. Then add what is missing after having a discussion with your team.
  • Use metas! Add context to any log so you can quickly filter over users, customers or any business centric attribute.

Further Reading

Additional helpful documentation, links, and articles:

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