fix(gateway): fix Caddyfile audit config and metrics deprecation

[flemzord]

Summary

• Make topic_name option conditional for Gateway >= v2.2.0 (older versions don't support this option and generate topic automatically via $STACK-audit)
• Move metrics directive from servers block to global level (servers.metrics is deprecated and will be removed in the next major Caddy version)

Context

Problem	Minimum Gateway Version	Solution
topic_name unrecognized	v2.2.0	Make option conditional based on version
metrics deprecated	N/A	Move to global Caddyfile level

Changes

• internal/resources/gateways/Caddyfile.gotpl: Added version check for topic_name and moved metrics to global level
• Updated golden test files to reflect the new Caddyfile structure

Test plan

• Verify Gateway < v2.2.0 starts without topic_name error
• Verify Gateway >= v2.2.0 works with topic_name option
• Verify metrics deprecation warning is resolved
• CI tests pass

[coderabbitai]

Walkthrough

The Caddyfile template is modified to conditionally include topic_name in the audit block based on gateway version, and the metrics endpoint configuration is relocated from the servers block to a global block.

Changes

Cohort / File(s)	Summary
Caddyfile Template Configuration internal/resources/gateways/Caddyfile.gotpl	Conditional topic_name emission in audit block (v2.2.0+); metrics endpoint moved from servers block to global level

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

🐰 Hoppy refactoring day!
Templates now dance with conditions bright,
Metrics leap to global sight,
Version checks guard our audit block right,
Caddyfile prances with delight! 🎉

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically describes both main changes: fixing the Caddyfile audit config (topic_name conditional logic) and addressing metrics deprecation, directly matching the changeset.
Description check	✅ Passed	The description is well-structured, directly addresses the changeset with clear explanations of both changes, provides context and rationale, and includes a test plan—fully related to the pull request.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch fix/gateway-caddyfile-audit-config

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[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@internal/resources/gateways/Caddyfile.gotpl`:
- Around line 15-18: The current template condition emits "topic_name
{$TOPIC_NAME}" when semver_is_valid($values.Gateway.Version) is false, which can
break older/non‑semver Gateways; change the guard so topic_name is only emitted
when semver_is_valid($values.Gateway.Version) is true AND
semver_compare($values.Gateway.Version "v2.2.0") >= 0 (or alternatively add an
explicit opt‑in flag check) — update the conditional around the topic_name block
(the if using semver_is_valid, semver_compare and $values.Gateway.Version) to
require both validity and >= v2.2.0 before rendering topic_name.

[coderabbitai]

⚠️ Potential issue | 🟠 Major

Fix version gate to avoid breaking non‑semver / older gateways.

Line 16 currently includes topic_name when the version is invalid, which can reintroduce the startup error for older (< v2.2.0) gateways running non‑semver tags. Consider only emitting when the version is valid and ≥ v2.2.0 (or add an explicit opt‑in flag for unknown versions).

🔧 Suggested adjustment

-		{{- if or (not (semver_is_valid $values.Gateway.Version)) (ge (semver_compare $values.Gateway.Version "v2.2.0") 0) }}
+		{{- if and (semver_is_valid $values.Gateway.Version) (ge (semver_compare $values.Gateway.Version "v2.2.0") 0) }}
 		topic_name {$TOPIC_NAME}
 		{{- end }}

📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change

	{{- /* topic_name option is only available in Gateway >= v2.2.0 */}}
	{{- if or (not (semver_is_valid $values.Gateway.Version)) (ge (semver_compare $values.Gateway.Version "v2.2.0") 0) }}
	topic_name {$TOPIC_NAME}
	{{- end }}
	{{- /* topic_name option is only available in Gateway >= v2.2.0 */}}
	{{- if and (semver_is_valid $values.Gateway.Version) (ge (semver_compare $values.Gateway.Version "v2.2.0") 0) }}
	topic_name {$TOPIC_NAME}
	{{- end }}

🤖 Prompt for AI Agents

In `@internal/resources/gateways/Caddyfile.gotpl` around lines 15 - 18, The
current template condition emits "topic_name {$TOPIC_NAME}" when
semver_is_valid($values.Gateway.Version) is false, which can break
older/non‑semver Gateways; change the guard so topic_name is only emitted when
semver_is_valid($values.Gateway.Version) is true AND
semver_compare($values.Gateway.Version "v2.2.0") >= 0 (or alternatively add an
explicit opt‑in flag check) — update the conditional around the topic_name block
(the if using semver_is_valid, semver_compare and $values.Gateway.Version) to
require both validity and >= v2.2.0 before rendering topic_name.