leo2d / grok.net

.net implementation of the grok 📝

grok.net

Cross platform .NET grok implementation as a NuGet package

How to Install

You can directly install this library from Nuget. There is package:

grok.net

PM> Install-Package Grok.Net

What is grok

Grok is a great way to parse unstructured log data into something structured and queryable. It sits on top of Regular Expression (regex) and uses text patterns to match lines in log files.

A great way to get started with building yours grok filters is this grok debug tool: https://grokdebug.herokuapp.com/

What can I use Grok for?

• reporting errors and other patterns from logs and processes
• parsing complex text output and converting it to json for external processing
• apply 'write-once use-everywhere' to regular expressions
• automatically providing patterns for unknown text inputs (logs you want patterns generated for future matching)

The syntax for a grok pattern is %{SYNTAX:SEMANTIC}

The SYNTAX is the name of the pattern that will match your text. SEMANTIC is the key.

For example, 3.44 will be matched by the NUMBER pattern and 55.3.244.1 will be matched by the IP pattern. 3.44 could be the duration of an event, so you could call it simply duration. Further, a string 55.3.244.1 might identify the client making a request. For the above example, your grok filter would look something like this:

%{NUMBER:duration} %{IP:client}

Examples: With that idea of a syntax and semantic, we can pull out useful fields from a sample log like this fictional http request log:

55.3.244.1 GET /index.html 15824 0.043

The pattern for this could be:

%{IP:client} %{WORD:method} %{URIPATHPARAM:request} %{NUMBER:bytes} %{NUMBER:duration}

More about grok

How to use

Create a new instanse with grok pattern:

Grok grok = new Grok("%{MONTHDAY:month}-%{MONTHDAY:day}-%{MONTHDAY:year} %{TIME:timestamp};%{WORD:id};%{LOGLEVEL:loglevel};%{WORD:func};%{GREEDYDATA:msg}");

then prepare some logs to parse

string logs = @"06-21-19 21:00:13:589241;15;INFO;main;DECODED: 775233900043 DECODED BY: 18500738 DISTANCE: 1.5165
               06-21-19 21:00:13:589265;156;WARN;main;DECODED: 775233900043 EMPTY DISTANCE: --------";

You are ready to parse and print result

var grokResult = grok.Parse(logs);
foreach (var item in grokResult)
{
  Console.WriteLine($"{item.Key} : {item.Value}");
}

Contributing

Please read CONTRIBUTING.md for details on our code of conduct, and the process for submitting pull requests to us.

License

This project is licensed under the MIT License - see the LICENSE.md file for details