Overhaul: Configuration (schema v3.0.0)

[josecelano]

Goal

Overhaul the Torrust Tracker configuration to schema version 3.0.0, incorporating pending enhancements, security improvements, and structural changes, many of which are breaking changes that justify the schema version bump.

Deliver a cleaner, more extensible, and more secure configuration model that supports modern deployment scenarios including reverse proxies, TLS, multi-instance metrics, logging flexibility, secrets management, and explicit trust policies.

Specification: docs/issues/open/1978-configuration-overhaul-epic.md

Why This Is Needed

1. No public URL awareness: the application cannot know its public-facing URLs (Include public service URL in configuration #1417), which affects metrics aggregation, API discoverability, and logging in reverse-proxy setups.
2. Global on_reverse_proxy: the setting applies to all HTTP trackers, preventing mixed deployments where only some trackers are behind a proxy (Support per-HTTP-tracker on_reverse_proxy setting #1640).
3. Secrets exposure risk: API tokens and database passwords can leak through tracing instrumentation and debug output; there is no systematic protection (Overhaul Secrets: consider using secrecy to handle secrets #1490).
4. Hardcoded IP-ban reset interval: cleanup timing is hardcoded, and the cleanup task is spawned once per UDP server instead of once globally (Allow setting the IP bans reset interval via configuration and remove duplicate execution of cronjob to clean bans #1453).
5. Missing protocol context in service identity: bare SocketAddr is used where ServiceBinding would provide protocol-aware identity for logs, health checks, and metrics (Make server listen URL available where server socket address is also available #1415).
6. No logging style configuration: TraceStyle is hardcoded, and the threshold field should become trace_filter to match tracing terminology (New config option for logging style #889).
7. No UDP connection ID validation policy: every UDP listener validates connection IDs strictly, preventing isolated compatibility listeners for non-compliant clients (Add configurable UDP connection ID validation policy #1136).
8. No opt-in support for the HTTP announce ip parameter: the parameter is parsed but ignored, so controlled deployments cannot choose to trust a client-provided peer address (Add per-HTTP-tracker config option to use peer IP from ip GET parameter (sub-issue of #1978) #1987).

Several changes are breaking, including schema reorganization, field renames, and removal of global [core.net], making this the right time to bump the configuration schema from 2.0.0 to 3.0.0.

Note on versioning: The tracker application and configuration schema use independent version systems. The tracker app goes from 3.0.0 to 4.0.0, while the config schema goes from 2.0.0 to 3.0.0.

Subissues

Order	Issue	Notes
1	#1979 - Copy v2_0_0 to v3_0_0 as baseline	Foundation for every schema-v3 change
2	#1981 - Fix tsl_config to tls_config typo	Mechanical rename before #1640
3	#1640 - Per-instance Network block	Establishes placement used by #1417, #1490, and #1987
4	#1417 - Public service URL	Depends on #1640
5	#1415 - Use ServiceBinding for service identity	Independent
6	#1453 - Configurable IP-ban reset interval and single cleanup task	Global UDP policy; ordered before related #1136
7	#1136 - Configurable UDP connection ID validation policy	Per-listener policy; strict by default
8	#1490 - Database decomposition and secrets overhaul	Depends on #1640
9	#889 - Logging style configuration	Independent
10	#1987 - Opt-in use of the HTTP announce ip parameter	Depends on #1640 and external prerequisite #1985
11	#1980 - Final cleanup and consumer migration	Must be last; depends on all other EPIC work

GitHub's native subissue hierarchy is the source of truth for completion status.

Dependency Summary

• Copy configuration schema v2_0_0 to v3_0_0 as baseline #1979 is the schema-v3 foundation.
• Fix tsl_config → tls_config typo across the codebase #1981 precedes Support per-HTTP-tracker on_reverse_proxy setting #1640.
• Support per-HTTP-tracker on_reverse_proxy setting #1640 precedes Include public service URL in configuration #1417, Overhaul Secrets: consider using secrecy to handle secrets #1490, and Add per-HTTP-tracker config option to use peer IP from ip GET parameter (sub-issue of #1978) #1987.
• Allow setting the IP bans reset interval via configuration and remove duplicate execution of cronjob to clean bans #1453 and Add configurable UDP connection ID validation policy #1136 are not functionally dependent, but are ordered together to establish global UDP ban policy before per-listener connection ID policy.
• Add per-HTTP-tracker config option to use peer IP from ip GET parameter (sub-issue of #1978) #1987 also depends on Rename peer_addr GET param to ip in HTTP announce request (BEP 3) #1985 outside this EPIC.
• Configuration overhaul final cleanup: remove global re-exports, migrate consumers to explicit versioned imports #1980 is the final integration and consumer migration step.

Scope

In Scope

• Bump the configuration schema from 2.0.0 to 3.0.0.
• Copy v2_0_0 to v3_0_0 as the starting point for breaking changes.
• Implement all eight configuration enhancements listed above.
• Remove global re-exports and migrate consumers to explicit v3 imports during final cleanup.
• Document migration and compatibility considerations.

Out of Scope

• Extracting packages/configuration into sub-packages, tracked in Overhaul: Packages #1669.
• Unrelated tracker core or protocol changes.
• Changes to the deployer's environment configuration format.