I’d like to log my messages and use named fields, so that they appear in Kibana available fields menu for an index. The Logstash configuration I use:

input {
  file {
    path => "/logs/combined.log"
    start_position => "beginning"
    sincedb_path => "/dev/null"
    codec => "json"
  }
}

filter {
  date {
    match => [ "timestamp", "ISO8601" ]
  }
}

output {
  elasticsearch {
    hosts => ["http://elasticsearch:9200"]
    index => "application-logs-%{+YYYY.MM.dd}"
  }
  stdout {
    codec => rubydebug
  }
}

The nest.js logger definition I use:

import { Injectable, LoggerService } from '@nestjs/common';
import * as logform from 'logform';
import * as winston from 'winston';

const logFormat = logform.format.combine(
  logform.format.timestamp(),
  logform.format.printf(({ timestamp, level, message, ...meta }) => {
    const logObject = {
      timestamp,
      level: level.toUpperCase(),
      message,
      ...meta,
    };
    return JSON.stringify(logObject);
  }),
);

@Injectable()
export class FileLoggerService implements LoggerService {
  private readonly logger: winston.Logger;

  constructor() {
    this.logger = winston.createLogger({
      level: 'info',
      format: logFormat,
      transports: [
        new winston.transports.File({
          filename: 'logs/error.log',
          level: 'error',
        }),
        new winston.transports.File({ filename: 'logs/combined.log' }),
      ],
    });

    if (process.env.NODE_ENV !== 'production') {
      this.logger.add(
        new winston.transports.Console({
          format: winston.format.simple(),
        }),
      );
    }
  }

  public log(message: string, meta?: any) {
    this.logger.info(message, meta);
  }

  public error(message: string, trace: string, meta?: any) {
    this.logger.error(message, { trace, ...meta });
  }

  public warn(message: string, meta?: any) {
    this.logger.warn(message, meta);
  }

  public debug(message: string, meta?: any) {
    this.logger.debug(message, meta);
  }

  public verbose(message: string, meta?: any) {
    this.logger.verbose(message, meta);
  }
}

And finally, how I do the logging in a controller:

this.logger.log(
  'Task management webhook invoked with {model}, {webhookEvent}, {externalId}.' +
    'The original message was: {request}.',
  {
    model: entry.model,
    event: entry.event,
    externalId: entry.entry.id,
    request: entry,
  },
);

The issue is that new documents get the _jsonparsefailure tag, and no additional fields are present for selection in Kibana.