Go Log Collection

To send your Go logs to Datadog, log to a file and then tail that file with your Datadog Agent. You can use the following setup with logrus, an open source logging library.

Datadog strongly encourages setting up your logging library to produce your logs in JSON to avoid the need for custom parsing rules.

Configure your logger

For a classic Go configuration, open a main.go file and paste in 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")
}

You can 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 can 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 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 reuse fields between logging statements by reusing
  contextualizedLog := log.WithFields(log.Fields{
    "hostname": "staging-1",
    "appname": "foo-app",
    "session": "1ce3f6v"
  })

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

Configure your Datadog Agent

Once log collection is enabled, set up custom log collection to tail your log files and send new logs to Datadog.

  1. Create a go.d/ folder in the conf.d/ Agent configuration directory.

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

    ##Log section
    logs:
    
      - type: file
        path: "/path/to/your/go/log.log"
        service: go
        source: go
        sourcecategory: sourcecode
    
  3. Restart the Agent.

  4. Run the Agent’s status subcommand and look for go under the Checks section to confirm logs are successfully submitted to Datadog.

If logs are in JSON format, Datadog automatically parses the log messages to extract log attributes. Use the Log Explorer to view and troubleshoot your logs.

Connect logs and traces

If APM is enabled for this application, the correlation between application logs and traces can be improved by following the APM Go logging documentation to automatically add trace and span IDs in your logs.

Best practices

  • Name the logger with a name that corresponds to the relevant functionality or service.
  • Use the DEBUG, INFO, WARNING, and FATAL log levels. In Datadog, Go’s FATAL maps to a severity level of Emergency.
  • Start with logging the information that is most important. Expand the comprehensiveness of your logging with further iterations.
  • Use metas to add context to any log. This enables you to quickly filter over users, customers, business-centric attributes, etc.

Further Reading