Refactoring and cleanup

[ncode]

This pull request includes significant refactoring and improvements to the logging and configuration handling in the outbound plugin, as well as updates to the testing framework. The most important changes include extracting the Go version from go.mod, restructuring the logging setup, and enhancing the configuration parsing logic.

Configuration and Build Improvements:

• Makefile: Extracted the Go version directly from go.mod and passed it as a build argument to the Docker build process. Introduced targets for testing and cleaning Docker images.

Logging Enhancements:

• outbound.go: Refactored the logging setup by renaming setupLogging to setupPluginLogging and updating the logging configuration process. Added new structured logging instances and metadata handling. [1] [2] [3]

Configuration Parsing Refactor:

• outbound.go: Split the parseConfig function into smaller, more manageable functions (readJSONConfig, setupPluginLogging, parsePrevResult, applyAdditionalRules). This improves readability and maintainability. [1] [2]

Testing Updates:

• outbound_test.go: Updated tests to reflect the refactored logging and configuration parsing functions. Added new tests to handle scenarios where parsing previous results or finding IPv4 addresses fails. [1] [2]

IPTables Management:

• pkg/iptables/iptables_manager.go: Added a new method RemoveJumpRuleByTargetChain to the Manager interface and updated the IPTablesManager implementation. [1] [2]

[codecov]

Codecov Report

Attention: Patch coverage is 94.65241% with 10 lines in your changes missing coverage. Please review.

Project coverage is 95.76%. Comparing base (90a2e77) to head (85c6d94).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
outbound.go	95.68%	4 Missing and 1 partial ⚠️
pkg/iptables/iptables_manager.go	92.95%	4 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #14      +/-   ##
==========================================
- Coverage   96.01%   95.76%   -0.26%     
==========================================
  Files           2        2              
  Lines         628      661      +33     
==========================================
+ Hits          603      633      +30     
- Misses         22       24       +2     
- Partials        3        4       +1     

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