feat: allow single-label hostnames in ValidateURL and improve performance

[Yashbhu]

Description

This PR relaxes the URL validation logic to support internal hostnames (single-label hostnames like http://harbor), which are standard in DevOps environments but were previously blocked. It also improves performance by optimizing regex handling.

• Fixes [bug]:The ValidateURL function fails to validate URLs that use single-label hostnames  #879

Type of Change

• Bug fix
• New feature
• Refactor
• Documentation update
• Chore / maintenance

Changes

• RFC 1123 Support: Updated the domain regex to allow hostnames without dots, enabling compatibility with Kubernetes service names and Docker Compose networking.
• Performance Optimization: Moved the domainNameRegex to a package-level global variable to avoid the overhead of re-compiling the regex on every ValidateURL call.
• Enhanced Testing: Added new unit test cases for internal service names (e.g., http://harbor, https://registry-server) and verified they pass alongside existing FQDN and IP tests.

[Yashbhu]

i did some changes in the helper_test.go:

http://harbor: It verifies that a simple, single-word hostname (which used to fail) now passes.
https://registry-server: This verifies that the regex correctly handles hyphens inside a single label. Many Kubernetes services use hyphens (like harbor-core), so i think we need to make sure they work
http://harbor:8080: This verifies that the hostname validation still works when a port number is attached to it we want to make sure our regex only looks at the host part and doesn't get confused by the :8080.

[Copilot]

Pull request overview

Updates URL host validation to accept single-label internal hostnames (common in in-cluster / DevOps setups) while reducing per-call overhead by reusing a precompiled domain regex.

Changes:

• Relaxed domain-name validation to allow single-label hostnames in ValidateURL.
• Moved the domain regex to a package-level precompiled regexp.Regexp for performance.
• Extended ValidateURL unit tests to cover internal service-name style hosts.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
pkg/utils/helper.go	Precompiles and reuses an RFC1123-style domain regex; ValidateURL now permits single-label hostnames.
pkg/utils/helper_test.go	Adds test cases verifying single-label hostnames (with/without hyphens/ports) are accepted.

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[Yashbhu]

@bupd PTAL whenever you have bandwidth
if this issue makes sense or not #879
thanks !

[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 8.56%. Comparing base (60ad0bd) to head (3ad9e11).
⚠️ Report is 162 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/api/instance_handler.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##             main    #880      +/-   ##
=========================================
- Coverage   10.99%   8.56%   -2.43%     
=========================================
  Files         173     288     +115     
  Lines        8671   14444    +5773     
=========================================
+ Hits          953    1237     +284     
- Misses       7612   13087    +5475     
- Partials      106     120      +14     

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[bupd]

I dont know why are you moving removing the var from here - just to declare above the function.

That doesnt make sense - is there any specific reason to do this.

thanks

[Yashbhu]

the only reason to move it outside i thought of is to avoid the overhead of re-compiling the regex on every call
though you are right to address it that in a CLI it's not much needed and rather clean code setup should be much prioritized i've reverted this
thanks !

[Yashbhu]

@bupd PTAL