Serilog Skill

VanDaemon uses Serilog 8.x for structured logging with console and file sinks. Logs use semantic message templates with named properties for queryability. The API layer configures Serilog in Program.cs with rolling file output to logs/vandaemon-{Date}.txt.

Quick Start

Basic Structured Logging

// Inject ILogger<T> via constructor
private readonly ILogger<TankService> _logger;

public TankService(ILogger<TankService> logger)
{
    _logger = logger;
}

// Use semantic message templates - property names in braces
_logger.LogInformation("Tank {TankId} updated to {Level}%", tankId, level);
_logger.LogWarning("Tank {TankName} below threshold: {CurrentLevel}% < {Threshold}%", 
    tank.Name, tank.CurrentLevel, tank.AlertLevel);

Exception Logging

try
{
    await plugin.SetStateAsync(controlId, state, ct);
}
catch (Exception ex)
{
    // Exception as FIRST parameter, then message template
    _logger.LogError(ex, "Failed to set state for control {ControlId}", controlId);
    throw;
}

Key Concepts

Concept	Usage	Example
Message Template	Named placeholders for structured data	"Processing {TankId}"
Log Level	Severity filtering	LogInformation, LogWarning, LogError
Enrichment	Automatic context properties	Enrich.FromLogContext()
Sink	Output destination	Console, File, Seq

Common Patterns

Service Layer Logging

When: Logging business operations with context

public async Task<Tank> UpdateTankAsync(Tank tank, CancellationToken ct)
{
    _logger.LogDebug("Updating tank {TankId}: {TankName}", tank.Id, tank.Name);
    
    // Business logic...
    
    _logger.LogInformation("Tank {TankId} saved successfully", tank.Id);
    return tank;
}

Plugin Lifecycle Logging

When: Tracking plugin initialization and disposal

public async Task InitializeAsync(Dictionary<string, object> config, CancellationToken ct)
{
    _logger.LogInformation("Initializing {PluginName} v{Version}", Name, Version);
    
    if (!config.TryGetValue("MqttBroker", out var broker))
    {
        _logger.LogWarning("{PluginName} missing MqttBroker config, using default", Name);
    }
}

See Also

• patterns - Structured logging patterns and enrichment
• workflows - Configuration and debugging workflows

Related Skills

• See the aspnet-core skill for middleware logging configuration
• See the dotnet skill for DI registration patterns
• See the docker skill for viewing container logs