ln-771-logging-configurator Skill

ln-771-logging-configurator

Type: L3 Worker Category: 7XX Project Bootstrap Parent: ln-770-crosscutting-setup

Configures structured JSON logging for .NET and Python projects.

Overview

| Aspect | Details | |--------|---------| | Input | Context Store from ln-770 | | Output | Logging configuration files | | Stacks | .NET (Serilog), Python (structlog) |

Phase 1: Receive Context

Accept Context Store from coordinator.

Required Context:

STACK: .NET or Python
FRAMEWORK: ASP.NET Core or FastAPI
FRAMEWORK_VERSION: Version number
PROJECT_ROOT: Project directory path
ENVIRONMENT: Development or Production

Validation:

If STACK not provided, detect from project files
If version not provided, use latest stable

Phase 2: Research Current Best Practices

Use MCP tools to get up-to-date documentation.

For .NET (Serilog):

MCP ref: "Serilog ASP.NET Core structured logging configuration"
Context7: /serilog/serilog-aspnetcore

For Python (structlog):

MCP ref: "structlog Python structured logging configuration"
Context7: /hynek/structlog

Key Patterns to Research:

Request logging middleware
Log enrichment (correlation ID, user context)
Log level configuration by environment
Sink configuration (Console, File, Seq, Elastic)

Phase 3: Decision Points

Ask user for configuration preferences.

Q1: Log Format

| Option | When to Use | |--------|-------------| | JSON (Recommended for Production) | Machine-readable, log aggregation systems | | Pretty/Colored (Recommended for Development) | Human-readable, local debugging |

Q2: Enrichment Fields

| Field | Description | Default | |-------|-------------|---------| | correlationId | Request tracking across services | ✓ Yes | | userId | Authenticated user identifier | ✓ Yes | | requestPath | HTTP request path | ✓ Yes | | responseTime | Request duration in ms | ✓ Yes | | machineName | Server hostname | Optional | | threadId | Thread identifier | Optional |

Q3: Log Sinks

| Sink | Use Case | |------|----------| | Console | Always enabled | | File | Local persistence, log rotation | | Seq | Structured log server | | Elasticsearch | Log aggregation at scale |

Q4: Log Levels by Environment

| Level | Development | Production | |-------|-------------|------------| | Default | Debug | Information | | Microsoft.* | Information | Warning | | System.* | Information | Warning | | Application | Debug | Information |

Phase 4: Generate Configuration

Generate files based on stack and decisions.

.NET Output Files

| File | Purpose | |------|---------| | Extensions/LoggingExtensions.cs | Service registration | | appsettings.json (update) | Serilog configuration | | appsettings.Development.json (update) | Dev overrides |

Generation Process:

Use MCP ref to get current Serilog API
Generate LoggingExtensions.cs with:
- UseSerilog configuration
- Request logging middleware
- Enrichment configuration
Update appsettings.json with Serilog section

Packages to Add:

Serilog.AspNetCore
Serilog.Sinks.Console
Serilog.Sinks.File (if File sink selected)
Serilog.Enrichers.Environment (if machineName selected)

Python Output Files

| File | Purpose | |------|---------| | core/logging_config.py | structlog configuration | | middleware/logging_middleware.py | Request logging |

Generation Process:

Use MCP ref to get current structlog API
Generate logging_config.py with:
- Processor chain configuration
- Renderer selection (JSON/Console)
- Log level configuration
Generate logging_middleware.py for FastAPI

Packages to Add:

structlog
python-json-logger (if JSON format)

Phase 5: Validate

Verify the configuration works.

Validation Steps:

Check imports: Ensure all packages are available
- .NET: dotnet list package | grep Serilog
- Python: pip list | grep structlog
Syntax check:
- .NET: dotnet build --no-restore
- Python: python -m py_compile core/logging_config.py
Test log output:
- Start application
- Make test request
- Verify log format matches configuration

Expected Log Format:

{
  "timestamp": "2026-01-10T12:00:00.000Z",
  "level": "info",
  "message": "Request completed",
  "correlationId": "abc-123",
  "requestPath": "/api/health",
  "responseTime": 45,
  "statusCode": 200
}

Return to Coordinator

Return result to ln-770:

{
  "status": "success",
  "files_created": [
    "Extensions/LoggingExtensions.cs",
    "appsettings.json"
  ],
  "packages_added": [
    "Serilog.AspNetCore",
    "Serilog.Sinks.Console"
  ],
  "registration_code": "services.AddLoggingServices(configuration);",
  "message": "Configured structured logging with Serilog"
}

Idempotency

This skill is idempotent:

Phase 1: Check if logging already configured (Grep for Serilog/structlog)
If configured: Return { "status": "skipped", "message": "Logging already configured" }
If not: Proceed with configuration

Reference Links

Critical Rules

Use MCP ref/Context7 for current API — do not hardcode Serilog/structlog config from memory
Idempotent — if Serilog or structlog already configured, return status: "skipped" immediately
Environment-aware log levels — Debug for Development, Information for Production (never Warning default)
Always include correlation ID enrichment — required for distributed tracing
Return structured response — files_created, packages_added, registration_code for coordinator aggregation

Definition of Done

Context Store received and validated (stack, framework, version)
Best practices researched via MCP tools for target stack
User decisions collected (format, enrichment, sinks, log levels)
Configuration files generated (extensions/config + appsettings or Python modules)
Syntax validated (dotnet build or py_compile)
Structured JSON response returned to ln-770 coordinator

Version: 2.0.0 Last Updated: 2026-01-10

Agent Skills: ln-771-logging-configurator

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