How to log messages with additional context information (e.g., request ID) in Go?

In Go, you can log messages with additional context information, such as a request ID, by using the log package and a custom logger that extends the log.Logger struct. Here's an example of how you can accomplish this:

Create a custom logger struct that includes the necessary fields for additional context information:

type customLogger struct {
    logger  *log.Logger
    requestID string
}

Create a new function to initialize and return a custom logger:

func NewCustomLogger(logger *log.Logger, requestID string) *customLogger {
    return &customLogger{
        logger:   logger,
        requestID: requestID,
    }
}

Add a new method to the custom logger to log messages with the request ID:

func (cl *customLogger) LogWithRequestID(message string) {
    cl.logger.Println(cl.requestID, message)
}

Use the custom logger in your application code:

func main() {
    logger := log.New(os.Stdout, "", log.LstdFlags)
    requestID := "1234"

    customLogger := NewCustomLogger(logger, requestID)
    customLogger.LogWithRequestID("This is an example log message")
}

With this approach, each log message output will include the request ID as additional context information.

Note: You can extend the custom logger struct with more fields, depending on the additional context information you want to include in your log messages.