added file size in metadata

README.md

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+# Fail2Ban Log Parser
+
+## About
+
+This is a mini weekend project i did as one of my first steps in learning golang. The binary takes a f2b log file as input and a output directory as output, in which it creates a parsed.json and state.json file. Parsed.json contains the logs in a structured file and state.json is the metadata used to track at which point the parser last checked and if the file rolled over (log files tend to wipe after a certain amount of rows or create copies of themselfes while wiping their contents.)
+
+## Usage
+
+To build the project run
+
+```bash
+make build
+```
+
+This will create a binary: `bin/parser`
+
+Once you run the binary you will get the usage menu:
+```
+Usage: ./bin/parser --destDir=<dir> --source=<file>
+  -d string
+    	Destination Directory (shorthand)
+  -destDir string
+    	Destination Directory
+  -s string
+    	Source Log File (shorthand)
+  -source string
+    	Source Log File
+```
+
+Lets say you have the following structure:
+
+```
+├── fail2ban/
+├── parser
+└── raw-logs/
+    └── fail2ban.log
+```
+
+You can run the parser:
+```
+./parser -destDir=./fail2ban -source=./raw-logs/fail2ban.log
+```
+
+The parser will read the source file and create `parsed.json`and `state.json` in your destination directory. _*If destination directory does not exist, the parser will try to create it._
+
+`parsed.json` will have the following structure:
+
+```
+[
+   {
+      "timestamp": "2025-10-19 00:00:01,810",
+      "handler": "fail2ban.server",
+      "level": "INFO",
+      "source": "",
+      "ipAddress": "",
+      "message": ""
+   },
+...
+]
+```
+
+You can import this in grafana or any other tool to analyse further.
+
+`state.json` will look like this:
+
+```
+{
+  "offset": 3703746,
+  "size": 6079112
+}
+```
+
+Offset is the size in Bytes of how far the fail2ban.log file was read when the command was run the last time.
+
+Size is the tracker of the parsed log file size in Bytes. - I have implemented this for myself to have an overview, maybe one day I will write rollover logic based on this.
+
+
+## More
+
+To read more about this project and how i made a Grafana dashboard you can read it on [My Blog](https://agres.online/blog/bruteforce)
+
+
+## Developed with
+
+- make
+- go 1.25.3
+- linux