登录到stdout并获取堆栈跟踪的字符串值

Question

I have a logger that logs stack traces to stdout. I want to get the stack trace that was logged into a string value so I can send it as a debug email.

Here is my current code:

func (l *Logger) withStack(writer io.Writer, err error) error {
    err = errors.WithStack(err)
    fmt.Fprintf(writer, "%+v
", err)
    return err
}

func (l *Logger) Error(err error) error {
    // Logs stack trace to `stdout`...
    l.withStack(os.Stdout, err)

    // Here I want to get the string value of what was logged to `stdout`.
}

But if the stdout stack trace looks like this:

foo
infrastructure/logger.(*Logger).withStack
    /Users/lansana/Projects/Go/src/app/src/infrastructure/logger/logger.go:40
infrastructure/logger.(*Logger).Error
    /Users/lansana/Projects/Go/src/app/src/infrastructure/logger/logger.go:50
main.main
    /Users/lansana/Projects/Go/src/app/src/microservices/api/main.go:44
runtime.main
    /usr/local/Cellar/go/1.9/libexec/src/runtime/proc.go:185
runtime.goexit
    /usr/local/Cellar/go/1.9/libexec/src/runtime/asm_amd64.s:2337

...then the result of err.Error() in the email is just foo.

I guess that makes sense, because the error itself only contains foo and not the stack trace itself, but how can I get the exact stack trace as a string value?

Answer 1

withStack doesn't log to stdout: it logs to whatever implementation of io.Writer you provide it with. To easily get a string, consider passing it a bytes.Buffer.

Your Error func could look like this:

func sendErrorMail(s string) error {
    // Send the stack trace `s` by email
}

func (l *Logger) Error(err error) {
    // Get the stack trace as a string
    buf := new(bytes.Buffer)
    l.withStack(buf, err)

    sendErrorMail(buf.String())
}

Simple demonstration of this idea as a playground.