Redirect QtDebug to Logstash - qt

Question

Are there best practice to redirecting QtDebug to logstash?
My mobile devices are write log by qDebug().
I want to aggregate all my logs to logstash then Google big query.
Current my logging is as below.
void SignUpDialog::signUp(QString email, QString password) {
qDebug() << "singUp " << email
I'm looking for appender for qt such as.

Answer 1

I think one solution is to to install message handler in you Qt app main (here with logic to prevent log from growing infinitely, running number and timestamp):
void msgHandler(QtMsgType type, const QMessageLogContext &/*context*/, const QString &msg)
{
static int i = 0;
static QString fp = "/tmp/qtapp.log";
static QFile f(fp);
if (!f.isOpen()) {
f.open(QIODevice::WriteOnly | QIODevice::Append);
}
static QTextStream ts(&f);
QString t;
switch (type) {
case QtDebugMsg:
t = QString("Debug (%1): %2").arg(++i, 0, 10).arg(msg);
break;
case QtInfoMsg:
t = QString("Info (%1): %2").arg(++i, 0, 10).arg(msg);
break;
case QtWarningMsg:
t = QString("Warning (%1): %2").arg(++i, 0, 10).arg(msg);
break;
case QtCriticalMsg:
t = QString("Critical (%1): %2").arg(++i, 0, 10).arg(msg);
break;
case QtFatalMsg:
t = QString("Fatal (%1): %2").arg(++i, 0, 10).arg(msg);
break;
default:
break;
}
QTime time = QDateTime::currentDateTime().time();
t = time.toString("hh:mm:ss.zzz") + " " + t;
ts << t << endl;
fprintf(stderr, "%s\n", t.toStdString().c_str());
QString fpo(fp + QString(".old"));
if (f.size() > 65011712) {
f.close();
QFile::remove(fpo);
QFile::rename(fp, fpo);
}
}
int main(int argc, char *argv[])
{
qInstallMessageHandler(msgHandler);
Logstash file input (just googled this, didn't try):
input {
file {
path => "/tmp/qtapp.log"
type => "qtapp-access"
start_position => "beginning"
}
}

Answer 2

Take a look into the official docs about the QtMsgHandler
You need to install a message handler using qInstallMsgHandler function, and then, redirect it.
#include <QtGlobal>
#include <stdio.h>
#include <stdlib.h>
void myMessageHandler(QtMsgType type, const QMessageLogContext &context, const QString &msg) {
QByteArray localMsg = msg.toLocal8Bit();
switch (type) {
case QtDebugMsg:
// Do whatever you need
break;
case QtInfoMsg:
// Do whatever you need
break;
...
case QtFatalMsg:
// Do whatever you need
abort();
}
}
int main(int argc, char **argv) {
qInstallMessageHandler(myMessageHandler);
QApplication app(argc, argv);
...
return app.exec();
}
To redirect your request you will need to use an existing client or write your own to send the different events to the Logstash API.