Refactor Logging for Native .NET Support and Container Readiness

[stephbu]

Overview
Refactor the logging system to leverage native .NET logging APIs, support configurable log verbosity levels, and ensure logs are suitable for container environments.

Requirements

• Migrate existing custom logging to .NET built-in logging (Microsoft.Extensions. Logging).
• Allow configuration of log verbosity via environment variables and .NET standard mechanisms.
• Ensure output format and streaming are compatible with common container runtimes (e.g., Docker, K8s) and aggregate log tools.
• Remove legacy/custom logger code that can be replaced by native approaches.
• Add documentation/examples for configuring logging in container scenarios.

Acceptance Criteria

• All service logs routed through . NET logging abstractions.
• Log level settable via environment (e.g., LOG_LEVEL) and .NET standard config.
• Logs stream correctly to container stdout/stderr for aggregation.
• Clean, maintainable code without obsolete logging artifacts.
• Clear migration notes in README.

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See also: .NET logging docs https://learn. microsoft.com/en-us/dotnet/core/extensions/logging

[stephbu]

Implementation Plan

Current State Analysis

The codebase has 61 Console.WriteLine calls across multiple files acting as ad-hoc logging:

• Dns/DnsServer.cs – Server startup, request/response logging, DNS discovery (5 calls)
• Dns/DnsMessage.cs – Diagnostic dump methods (26 calls)
• Dns/RData.cs – Record data dumps (13 calls)
• Dns/ResourceRecord.cs – Resource record dumps (5 calls)
• Dns/SmartZoneResolver.cs – Zone reload notifications (1 call)
• Dns/UdpListener.cs – Exception logging, endpoint debugging (4 calls)
• Dns/ZoneProvider/Bind/BindZoneProvider.cs – Parse error reporting (4 calls)
• Dns/ZoneProvider/FileWatcherZoneProvider.cs – Zone generation failures (1 call)
• Dns/ZoneProvider/IPProbe/* – Probe diagnostics (3 calls)
• dns-cli/Program.cs – Application startup/shutdown messages (2 calls)

The project already references Microsoft.Extensions.DependencyInjection and Microsoft.Extensions.Hosting (v10.0.0) but lacks explicit Microsoft.Extensions.Logging packages.

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Design Decisions (Resolved)

Question	Decision
Log format	Standard console formatter with UTC datetime prefix
Dump methods (DnsMessage.Dump(), RData.Dump(), etc.)	Leave as-is – diagnostic helpers, not operational logging
Environment variable	Create simple LOG_LEVEL alias that maps to .NET logging levels
Breaking changes	Acceptable to modify constructor signatures to accept ILogger<T>
dns-cli host	Should use/provide the same logging infrastructure
T16 relationship	Closely related – cross-reference in task list and docs

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Implementation Phases

Phase 1: Infrastructure Setup

1. Add NuGet packages to Dns.csproj:
   • Microsoft.Extensions.Logging
   • Microsoft.Extensions.Logging.Console
2. Wire up logging in DI container (BuildServiceProvider in Dns/Program.cs)
3. Add Logging configuration section to appsettings.json:

   "Logging": {
     "LogLevel": {
       "Default": "Information",
       "Dns": "Information"
     },
     "Console": {
       "TimestampFormat": "yyyy-MM-ddTHH:mm:ssZ ",
       "UseUtcTimestamp": true
     }
   }

4. Implement LOG_LEVEL environment variable alias that maps to Logging:LogLevel:Default

Phase 2: Core Service Migration

5. Inject ILogger<T> into core services:
   • DnsServer
   • SmartZoneResolver
   • HttpServer
   • UdpListener
6. Replace operational Console.WriteLine calls with appropriate log levels:
   • Information: Server startup (DNS server listening on port {Port}), zone reloads
   • Debug: DNS request/response logging ({Endpoint} asked for {Name} {Class} {Type})
   • Warning: Parse failures, zone generation issues
   • Error: Exceptions, critical failures

Phase 3: Zone Provider Migration

7. Inject ILoggerFactory into BaseZoneProvider base class
8. Migrate logging in:
   • BindZoneProvider – parse errors → Warning/Error
   • FileWatcherZoneProvider – generation failures → Error
   • IPProbeZoneProvider – probe diagnostics → Debug/Information

Phase 4: dns-cli Integration

9. Configure logging in dns-cli/Program.cs using the shared infrastructure
10. Replace startup/shutdown Console.WriteLine with ILogger calls

Phase 5: Container Readiness

11. Verify logs write to stdout for container aggregation
12. Test with Docker to confirm log streaming behavior
13. Document environment variable configuration for container deployments

Phase 6: Documentation & Cleanup

14. Update README.md with logging configuration section:
    • Configuration file examples
    • Environment variable usage (LOG_LEVEL=Debug)
    • Container deployment examples
15. Update docs/task_list.md to cross-reference T16 ↔ Issue Refactor Logging for Native .NET Support and Container Readiness #36
16. Update docs/product_requirements.md section 4 (Observability) to note logging implementation

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Files to Modify

File	Changes
Dns/Dns.csproj	Add logging packages
Dns/appsettings.json	Add Logging configuration section
dns-cli/appsettings.json	Add Logging configuration section
Dns/Program.cs	Wire up logging in DI, add LOG_LEVEL env var support
Dns/DnsServer.cs	Inject ILogger, replace 5 Console.WriteLine calls
Dns/SmartZoneResolver.cs	Inject ILogger, replace 1 Console.WriteLine call
Dns/UdpListener.cs	Inject ILogger, replace 4 Console.WriteLine calls
Dns/HttpServer.cs	Inject ILogger (future logging hooks)
Dns/ZoneProvider/BaseZoneProvider.cs	Add ILoggerFactory support
Dns/ZoneProvider/Bind/BindZoneProvider.cs	Use ILogger, replace 4 Console.WriteLine calls
Dns/ZoneProvider/FileWatcherZoneProvider.cs	Use ILogger, replace 1 Console.WriteLine call
Dns/ZoneProvider/IPProbe/IPProbeZoneProvider.cs	Use ILogger, replace 2 Console.WriteLine calls
Dns/ZoneProvider/IPProbe/Strategy.cs	Use ILogger, replace 1 Console.WriteLine call
dns-cli/Program.cs	Use logging infrastructure, replace 2 Console.WriteLine calls
README.md	Add logging configuration documentation
docs/task_list.md	Cross-reference T16
docs/product_requirements.md	Update observability section

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Estimated Scope

• ~15-18 files modified
• ~25 operational Console.WriteLine calls migrated (excluding diagnostic Dump methods)
• New configuration surface for log levels
• Documentation updates

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Related

• Task T16 in docs/task_list.md – Trace logging tools (this issue implements core logging; T16 may cover additional structured tracing)
• PRD §4 – Observability & Monitoring requirements