Logging

Logging

Logging is the process of writing information into log files. Log files include information about various events that happened int the system

Purpose of logging

• Troubleshooting
• Information gathering
• Profiling
• Auditing
• Generating statistics

It helps in identifying errors. It is also used in detecting security incidents, application bottlenecks and generating usage data.

Events to log

• Input validation failures
• Authentication and authorization failures
• Application errors
• Configuration changes
• Application startup and shutdowns

Events not to log

• Application source code
• Session identification values
• Access tokens
• Passwords
• Personal data
• Database connection strings
• Encrypted values

Best practices

• Structured and done at different levels
• Contain context
• Understandable to humans and parsable by machines
• Adapted to development and production
• Can be divided into several log files

Writing log messages

logger.info('server.endpoint.get.users.getusersfromdb.format');

const handler = (func) => (req, res) => {
    try {
        logger.info('server.handler.begun');
        func(req, res, logger);
    } catch(e){
        logger.info('server.handler.failed');
        res.send('Oh no, something did not go well!');
    }
};

More links:

• Retrace

Ref:

• http://zetcode.com/javascript/winston
• https://stackify.com/winston-logging-tutorial