Overhaul: Configuration (schema v3.0.0)

[josecelano]

Goal

Overhaul the Torrust Tracker configuration to schema version 3.0.0, incorporating multiple 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 (reverse proxies, TLS, multi-instance metrics, logging flexibility, secrets management).

Spec: docs/issues/drafts/configuration-overhaul-epic.md

Why This Is Needed

The current configuration schema (v2.0.0) has accumulated several limitations:

1. No public URL awareness — the application cannot know its own public-facing URLs (Include public service URL in configuration #1417), which breaks 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 some trackers are behind a proxy and others are not (Support per-HTTP-tracker on_reverse_proxy setting #1640).
3. Secrets exposure risk — API tokens and database passwords can leak via tracing instrumentation and debug output; no systematic protection (Overhaul Secrets: consider using secrecy to handle secrets #1490).
4. Hardcoded IP bans reset interval — the ban cleanup interval 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 (protocol + address) would provide richer context 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 to Default, not configurable (New config option for logging style #889). Additionally, the threshold field name is misleading — it should be renamed to trace_filter to match tracing crate terminology.

Several of these changes are breaking (schema reorganisation, field renames, removal of global [core.net]), making this the right time to bump the schema version 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 → 4.0.0, while the config schema goes from 2.0.0 → 3.0.0.

Subissues

Order	Issue	Status	Notes
1	Copy v2_0_0 → v3_0_0 as baseline	TODO	Foundation: all other subissues depend on this
2	Fix tsl_config → tls_config typo	TODO	Mechanical rename; ~21 files; before #1640
3	#1640 — Per-instance Network block	TODO	Heaviest change (~30 files); before #1417 and #1490
4	#1417 — public_url config field	TODO	After #1640
5	#1415 — ServiceBinding instead of bare SocketAddr	TODO	Independent; parallel with #6, #7, #8
6	#1453 — IP bans reset interval	TODO	Independent; parallel with #5, #7, #8
7	#1490 — Decompose database config + secrecy crate	TODO	After #1640; parallel with #5, #6, #8
8	#889 — Logging style config	TODO	Independent; parallel with #5, #6, #7
9	Final cleanup: remove global re-exports	TODO	Must be last

Dependency Graph

1 (copy baseline)
 ├── 2 (tsl→tls typo) → 3 (#1640 Network)
 │                           ├── 4 (#1417 public_url)
 │                           └── 7 (#1490 secrets)
 ├── 5 (#1415 ServiceBinding) ── independent
 ├── 6 (#1453 IP bans)         ── independent
 └── 8 (#889 logging)          ── independent
      └── all → 9 (final cleanup)

Critical path

1 → 2 → 3 → 4 → 9 and 1 → 2 → 3 → 7 → 9

Scope

In Scope

• Bump configuration schema version from 2.0.0 to 3.0.0
• Copy v2_0_0 module to v3_0_0 as the starting point for breaking changes
• All six configuration enhancements listed above
• Final cleanup: remove global re-exports, migrate all consumers to explicit v3 imports

Out of Scope

• Extracting packages/configuration into sub-packages (tracked in Overhaul: Packages #1669 EPIC)
• Non-configuration changes to tracker core or protocol packages
• Changes to the deployer's environment config format