github.com/yayua/kvlog

Key=Value Log Formatter for Logrus

This package provides a text formatting type for Logrus.
It is similar to the text formatter that comes with Logrus, but is focused on compatibility with logging systems such as Splunk.

It provides a number of features

• All fields logged as key=value format (which Splunk automatically extracts).
• Fields keys are sorted into lexicographical order.
• Important/primary fields can be pinned to the start of each log entry so they're easy to spot.
• Constant fields can be defined within the formatter. For example, a build commit hash can be included in every log entry automatically.
• All string types are wrapped in quotes automatically.
• Types can define their own marshaler for custom behaviour
• Compound types can return multiple key/value pairs by implementing a Loggable interface.
• The calling function can optionally be included in every log entry.

Example usage:

log.SetFormatter(
    kvlog.New(
        // include the calling function name
        kvlog.IncludeCaller(), 

        // ensure action and status always appear first
        kvlog.WithPrimaryFields("action", "status")))

log.WithFields(log.Fields{
    "action":          "user_login",
    "status":          "ok",
    "username":        "joe_user",
    "email":           "[e-mail]",
    "active_sessions": 4,
}).Info("User logged in")

// Output:
//  2017-01-02T12:00:00.000Z ll="info" srcfnc="Example" srcline=29 action="user_login" status="ok" active_sessions=4 email="[e-mail]" username="joe_user" _msg="User logged in"