Logrus向contextlogger添加额外的字段

I use logrus in all my go apps and recently I started using a context logger. Now I want to "build up" a context during the execution path of my app. See example below, which illustrates what I want.

package main

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

func main() {
    logrus.Info("normal logger")

    cl := logrus.WithFields(
        logrus.Fields{
            "extra_field_one": "extra_value_one",
        })

    // some code here

    // here I want to add an additional field to to contextlogger cl.
    // How do I do that?

}

EDIT

As ymonad mentioned, it's possible by overwriting the contextLogger. Also found out that you can add one additional field:

cl = cl.WithField("key", "value")

You can just call cl.WithFields()

package main

import "github.com/Sirupsen/logrus"

func main() {
    cl := logrus.WithFields(
        logrus.Fields{
            "extra_field_one": "extra_value_one",
        })
    cl = cl.WithFields(
        logrus.Fields{
            "extra_field_two": "extra_value_two",
        })
    cl.Info("hello world")
}

Output is:

INFO[0000] hello world extra_field_one="extra_value_one" extra_field_two="extra_value_two"