How to store output of logrus to some variable?

Question

This is code that converts the entered value to JSON format. It shows the correct output but I want to store that output and return it using fmt.Printf

package main

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

func main() {
    log.SetFormatter(&log.JSONFormatter{})
    standardFields := log.Fields{
        "Number of threads": "1",
        "Odd number":        "3",
    }
    log.WithFields(standardFields).Info("Golang")
}

Answer 1

When you create a new logger with logrus.New(), you can provide the Out field to point to any io.Writer you wish. Here's the documentation for this field:

type Logger struct {
    // The logs are `io.Copy`'d to this in a mutex. It's common to set this to a
    // file, or leave it default which is `os.Stderr`. You can also set this to
    // something more adventurous, such as logging to Kafka.
    Out io.Writer
    ...
    ...

So, for example you could create a new bytes.Buffer and set that as the Out field. This is akin to "logging to a variable".

Similarly, you can set the output of the default logger with the SetOutput function.