[MONIT-4106] Add Support for User-Provided Lua Scripts in Fluent Bit Helm Chart

Description

This merge request introduces support for user-provided Lua scripts in the Fluent Bit Helm chart. The enhancement allows users to define custom Lua scripts via Helm chart values, simplifying the configuration and extending the customization capabilities of Fluent Bit for logs and metrics.

Motivation

While replicating the OpenShift logging setup, we identified the need for Lua script support in our Helm chart. The current implementation required adding secrets one by one, which was cumbersome and error-prone. By enabling Lua scripts to be defined in the Helm chart values, we align with best practices and simplify the setup process for users. This feature mirrors the behavior of the Fluent Bit official Helm chart and improves the usability of our solution.

Commits

• 6056aee5: [MONIT-4106] fluentbit/logs: Add support for user-provided Lua scripts
• b24b0d7e: [MONIT-4106] values/logs/fluentbit: Add default LuaScripts value
• c6c3db28: [MONIT-4106] fluentbit/metrics: Add support for user-provided Lua scripts
• 283d6fa3: [MONIT-4106] values/metrics/fluentbit: Add default LuaScripts value
• f9c08b91: [MONIT-4106] docs/logs/fluentbit: Add user-provided Lua scripts documentation
• 72463f9c: [MONIT-4106] docs/metrics/fluentbit: Add user-provided Lua scripts documentation

Related Jira Tickets

• MONIT-4106: Enable user-provided Lua scripts in Fluent Bit Helm chart.

docs/logs.md

@@ -101,6 +101,21 @@ outputs: |
       http_passwd {{ .Values.tenant.password }}
 ```
 
+### Fluentbit Custom Lua Scripts
+In Fluent Bit we can use Lua scripts to create processors that transform the records. These scripts are available in the Fluent Bit container under the path `/fluent-bit/etc/scripts`. In order to create new Lua scripts just add them in the values `logs.fluentbit.luaScripts` key.
+
+For example, the following configuration will create two files in `/fluent-bit/etc/scripts`. One named `my_lua_script.lua` and another one named `my_lua_script2.lua`.
+```yaml
+luaScripts:
+  my_lua_script.lua: |
+    function my_function(tag, timestamp, record)
+      // Do something...
+      return 2, timestamp, record
+      end
+  my_other_lua_script.lua: |
+    ...
+```
+
 ## 3. Customizing Fluentbit for Additional Log Sources
 
 You can extend the logging configuration by extending previous configurations with custom Fluentbit **inputs**, **filters**, or **outputs**. This is especially useful if you want to gather logs from additional sources or apply different processing to specific logs.