express-session-logger

A simple way for add custom context to all logs into you express session

Comes with a pre configured winston logger

Support for custom loggers. Any logger with .child interface should work.

Manage log verbosity with environment variable: process.env.LOG_LEVEL

Module interface

• contextMiddleware => (opt) => (req,res,next): express middleware

 * @param {*} opt options
 * @param {string=} opt.idField - idField
 * @param {string=} opt.ontextField - contextField
 * @param {function=} opt.id - id mapper
 * @param {function=} opt.context - context mapper
 * @param {Object=} opt.loggerInstance - custom loggerInstance

Example:

app.use(contextMiddleware({
  loggerInstance: //ex. winston logger, pino logger or undefined for default logger
  idField: '_id',
  id: (req) => req.header.x-request-id, // or uuid.v4()
  contextField: '_context',
  context: (req) => ({
    stage: process.env.STAGE,
    service: process.env.SERVICE,
    reqContext: req.someInterestingRequestInfo
  }),
}));

• logger: A logger instance (pre configured winston logger by default)

NOTE: logger is equal to loggerInstance if its defined in contextMiddleware, or default logger in other case

In this example, all logs via logger for this express request have the structure

{
  "_id": //id value
  "_context": {
    "stage": "...", //stage
    "service": "...",//service name
    "reqContext": {
      // someInterestingRequestInfo
    }

  }
  //....remaining info, depends on log instance
}

So, you can correlate easily all logs in one session

Default logger

WIP:...