Adding methods to exclude request URL paths and response status codes

[tovar-rodrigo]

Adding methods to get excluded request URL paths and response status codes

Avoid metrics creation in HandlerFunc based on excludedPaths and excludedStatusCodes slices

[gemini-code-assist]

Hello @tovar-rodrigo, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

Summary of Changes

This pull request introduces functionality to exclude specific request URL paths and response status codes from being monitored by Prometheus. This is achieved by adding methods to set and retrieve lists of excluded paths and status codes. The middleware handler is then modified to check incoming requests against these exclusion lists, preventing metrics creation for excluded requests.

Highlights

• Exclusion Methods: Adds ExcludePaths and ExcludeStatusCodes methods to the Prometheus struct, allowing users to specify URL paths and status codes to exclude from Prometheus monitoring (lines 362-379).
• Exclusion Logic: Modifies the HandlerFunc to check if the request URL path or response status code is in the exclusion lists before creating metrics (lines 385-393).
• State variables: Introduces excludedPaths and excludedStatusCodes variables to store the lists of excluded paths and status codes (lines 19-21).

Changelog

• middleware.go
  • Adds slices import for checking if a slice contains a value (line 8).
  • Introduces excludedPaths and excludedStatusCodes variables to store the lists of excluded paths and status codes (lines 19-21).
  • Adds ExcludePaths, GetExcludedPaths, ExcludeStatusCodes, and GetExcludedStatusCodes methods to the Prometheus struct (lines 362-379).
  • Modifies the HandlerFunc to check if the request URL path or response status code is in the exclusion lists before creating metrics (lines 385-393).

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Trivia time!

What is the purpose of the slices package in Go, introduced in Go 1.21?

Click here for the answer

The `slices` package in Go provides various utility functions for working with slices, such as searching, comparing, and manipulating slices. It aims to provide a more convenient and efficient way to perform common slice operations.

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[gemini-code-assist]

Code Review

The pull request introduces functionality to exclude specific URL paths and response status codes from being monitored by Prometheus. This is a useful addition for filtering out irrelevant or noisy metrics. The implementation appears straightforward, but there are a few areas that could be improved for clarity and efficiency.

Summary of Findings

• Global variable usage: The use of global variables excludedPaths and excludedStatusCodes can lead to potential issues with concurrency and testability. Consider using options or a configuration struct to manage these exclusions.
• Inefficient slice appending: Appending to slices in the ExcludePaths and ExcludeStatusCodes functions without pre-allocation can lead to performance issues if a large number of paths or status codes are excluded. Pre-allocate the slice with the expected capacity to avoid reallocations.
• Duplicated conditional logic: The conditional logic to check for excluded paths and status codes is duplicated in the HandlerFunc. This can be simplified by combining the conditions into a single check.

Merge Readiness

While the changes introduce valuable functionality, the use of global variables and potential performance issues with slice appending should be addressed before merging. I recommend refactoring the code to use options or a configuration struct for managing exclusions and pre-allocating the slices to improve efficiency. I am unable to approve this pull request, and recommend that others review and approve this code before merging.