Collect logs from os pipe

[Santiago Figueroa-Lorenzo]

Hello logrus experts,

I need to collect each of the logs issued by logrus and then apply a sha256 and a base64 as part of the code that generates the log itself, this (base64(sha256(log))) associated with the unique identifier (uuid) of each log, as a key-value, will allow to ensure the integrity of the log when I send it to an ELK infrastructure.

• Does the library include a way to do this, i.e., to collect the log that has been emitted within a string?

• If not, Could it be done via os.pipe?

Thanks in advance,

Santiago.

[David Bariod]

You could do that with a hook.
It can iterate an all fields and the message and other field you want to check to generate such a hash.
AFAIK, nobody has already implemented such a hook though.

[Santiago Figueroa-Lorenzo]

Hi @dgsb, in order to solve the issue I have package the logrus log into a captureOutput function, as you can see below:

However, now when the sha256 and base64 are calculated for each of the logs, the result is always the same, as you will see in the figure below.

I am adding the generated logs, highlighting the logs with the same uuid as the previous image:

I presume that the problem is in the function to capture the logs (captureOutput):

`package main

import (
"io"
"os"
"log"
"sync"
"bytes"
)

func captureOutput(f func()) string {
reader, writer, err := os.Pipe()
if err != nil {
panic(err)
}
stdout := os.Stdout
stderr := os.Stderr
defer func() {
os.Stdout = stdout
os.Stderr = stderr
log.SetOutput(os.Stderr)
}()
os.Stdout = writer
os.Stderr = writer
log.SetOutput(writer)
out := make(chan string)
wg := new(sync.WaitGroup)
wg.Add(1)
go func() {
var buf bytes.Buffer
wg.Done()
io.Copy(&buf, reader)
out <- buf.String()
}()
wg.Wait()
f()
writer.Close()
return <-out
}`

I will appreciate any suggestions,

Santiago

[Santiago Figueroa-Lorenzo]

I have an update @dgsb. I have tried to reproduce the problem here and when I use log.Println instead of logrus, the base64 is generated properly:

However, when I set logrus the problem appears again:

So, my point is, why am I not able to collect logs using logrus?

Note: In the examples I am using other log structure. #

[David Bariod]

I don't understand what your problem is but:

• it is probably unrelated to logrus
• the uuid isn't changing because you're capturing its value in the closure
• if you eventually find a logrus bug, we'll be happy to help, but you need to provide at least a minimal code sample which exhibits the problem

[github-actions]

This issue is stale because it has been open for 30 days with no activity.

[github-actions]

This issue was closed because it has been inactive for 14 days since being marked as stale.