filter errors from text based log files such as php, nginx, apache etc.

elog can find and filter specified error logs from your applications, web servers and any other text based log files, store the logs into MongoDB. And you can access the logs from MongoDB via a web interface with some filter options.

elog contains elog-client and elog-server, elog-client can filter and push logs to elog-server via http requests, elog-server is a kind of web server with expressjs.

Before you start, you need to install nodejs (>= 0.8.8) and CoffeeScript (>=1.3.3) in your Linux/Unix system, then install elog:

$ [sudo] npm -g install elog

client settings: elog-client

It's a standard JSON file, You need to specify the log files for each app and api like below.


        "apps": [
                "name": "app name",
                "file": "/tmp/php_errors.log",
                "interval_time": 5000,
                "position": 0,
                "rules": [
                    ["error", "LOG_ERROR"],
                    ["Notice", "LOG_WARN"]
                "name": "nginx",
                "file": "/usr/local/nginx/logs/error.log",
                "interval_time": 5000,
                "position": 0,
                "rules": [
                    ["error", "LOG_ERROR"],
                    ["alert", "LOG_WARN"]
        "api": {
            "key": "mykey",
            "url": "http://localhost:3339/api"

for each app, there are 5 parameters:

  • name: name of your app, (Note: don't put comma ',' in it')
  • file: log file path
  • interval_time: every number of seconds to check new logs
  • position: read data from log file in the specified positon after elog-client is started
  • rules: define some rules to filter logs, it's an array, each element in the array contains 2 elements, the first one is a regular expression, the sedond one is log level (LOG_FATAL, LOG_ERROR, LOG_WARN, LOG_INFO, LOG_DEBUG)

Also, you need to define an api key and url like above, the api key is just a random string which need to match the server side api key settings.

server settings: elog-server


    "api_key": "mykey",
    "http": {
        "host": "localhost",
        "port": 3339
    "mongodb": {
        "port": 27017,
        "host": "localhost",
        "database": "elog",
        "collection": "logs"
    "web": {
        "title": "elog",
        "limit_per_page": 100,
        "refresh_time": 10000

The server side settings is also a standand JSON file:

  • api_key: api key for the authentication, elog-client should send the same api key to match this one when push logs.
  • http: define a host and port to start a web server.
  • mongodb: mongodb related settings
  • web: web page related settings

start client

$ nohup elog-client /etc/elog/client.json > /var/log/elog-client.log &

start server

$ nohup elog-server /etc/elog/server.json > /var/log/elog-server.log &

If something went wrong, you can check the log files you specified such as above.

reload client or server In case if you changed some configuration, we can reload the settings without shutdown the client or the server process, just reload it:

$ elog-server reload  # server side
$ elog-client reload  # client side

we are using mocha with should for the test, run test in elo directory:

$ mocha -r should --compilers coffee:coffee-script

Known issues:

  • It doesn't work with logs with multiple bytes.
  • It only can process logs line by line.