Go Agent v0.4.3

October 16, 2024

Fixed Fixed the error collecting os.Stdout and os.Stderr logs.

• It modified the trace.Init function to enable log collection. It changes to run before other log libraries if possible.

• The function has been added that allows to use io.Writer that wraps os.Stdout and os.Stderr.

---

Below are instructions to use the changed log collection feature.

Configuring the agent

Set agent options in the whatap.conf file before running the application.

whatap.conf

logsink_enabled=true

# Enable stdout collection
logsink_stdout_enabled=true

# Enable stderr collection
logsink_stderr_enabled=true

# Optional. This is a setting for compressing data. 
logsin_zip_enabled=true

Before initializing the logging library

First, you have to call the trace.Init() function. It internally wraps os.Stdout and os.Stderr. Afterwards, the log library automatically collects logs when os.Stdout and os.Stderr have been set.

Example of the zap library

If you call the trace.Init() function before setting os.Stdout, logs are collected automatically. It collects logs by using the WhaTap log while outputting to os.Stdout.

zap library example

import (
    "github.com/whatap/go-api/trace"
    "github.com/whatap/go-api/logsink"
    
    "go.uber.org/zap"
    "go.uber.org/zap/zapcore"
)

func main() {
    trace.Init(nil)
    //It must be executed before closing the app.
    defer trace.Shutdown()

    // fmt.Println("Logger stdout=", os.Stdout, zapcore.AddSync(os.Stdout))
    consoleCore := zapcore.NewCore(
        zapcore.NewConsoleEncoder(consoleEncoderConfig), 
        zapcore.AddSync(os.Stdout),                      
        zap.InfoLevel,
    )

    // Menggabungkan core file dan console
    core := zapcore.NewTee(consoleCore)
    Log = zap.New(core, zap.AddCaller(), zap.AddStacktrace(zapcore.ErrorLevel))
    Log.Info("logger started")

    ...
}

After initializing the logging library

You can set the io.Writer wrapped through the configuration function in the logging library.

• logsink.GetWriterHookStdout(): It returns io.Writer that has wrapped os.Stderr. It collects the log by using the WhaTap log while outputting to os.Stdout.

• logsink.GetWriterHookStderr(): It returns io.Writer that has wrapped os.Stderr. The wrapped io.Writer outputs to os.Stderr and collects the log contents by using the WhaTap log.

• The log package

  sets os.Stderr at the import time (in the init function). Because the trace.Init function cannot be called first, set the wrapped io.Writer (os.Stderr) through the log.SetOutput function.

The output using the print function of the log package used afterwards is output to os.Stderr through the wrapped io.Writer and the log contents are collected as WhaTap logs.

log package

import (
	"log"
	"github.com/whatap/go-api/logsink"
)

...

if logsink.GetWriterHookStderr() != nil {
    // set single writer
    log.SetOutput(logsink.GetWriterHookStderr())	
    
    // set multi writer 
    multi := io.MultiWriter(file, logsink.GetWriterFromStderr())
    log.SetOutput(logsink.GetWriterHookStderr())
}

// 
log.Println("aaaaa")

...

Info

Download

• go-api(import library)

  go get github.com/whatap/go-api@v0.4.3

• Service agent

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  		aarch64	Download
  Ubuntu 12 and above / Debian	DEB	amd64	Download
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  Alpine linux	tar gzip	x86 x64	Download
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