Emitting Custom Logs — Node Observability

Basic Usage

public override async Task<NodeExecutionResult> ExecuteAsync(
    NodeExecutionContext ctx, CancellationToken ct)
{
    var logger = ctx.Observability.Logger;

    logger.LogInformation("Processing payment for order {OrderId}, amount {Amount}",
        orderId, amount);

    try
    {
        var result = await _paymentService.ProcessAsync(orderId, amount, ct);
        logger.LogInformation("Payment processed successfully. TransactionId: {TxId}",
            result.TransactionId);
        return NodeExecutionResult.Success(result);
    }
    catch (PaymentDeclinedException ex)
    {
        logger.LogWarning("Payment declined for order {OrderId}: {Reason}",
            orderId, ex.Reason);
        return NodeExecutionResult.Fail("Payment declined: " + ex.Reason);
    }
    catch (Exception ex)
    {
        logger.LogError(ex, "Unexpected error processing payment for order {OrderId}", orderId);
        throw;  // Let BaseNodeExecutor handle retry logic
    }
}

Do and Don't

Do	Don't
`logger.LogInformation("Order {Id}", orderId)`	`logger.LogInformation($"Order {orderId}")` (string interpolation — loses structure)
Log milestones and key values	Log every loop iteration at Info (use Debug/Trace)
Log exceptions with `LogError(ex, ...)`	Log exception.Message only — log the full exception object
Use ctx.Observability.Logger	Inject ILogger<T> directly into the executor constructor
Redact PII before logging	Log raw email addresses, phone numbers, or payment details

Structured Fields Are Automatically Included

// When you call:
logger.LogInformation("Payment processed. TxId: {TxId}", txId);

// The resulting Loki entry contains:
{
  "message"    : "Payment processed. TxId: ABC123",
  "TxId"       : "ABC123",          // ← named argument becomes a field
  "nodeId"     : "node-payment",    // ← added by INodeLogger
  "executionId": "exec-abc-123",    // ← added by INodeLogger
  "tenantId"   : "tenant-001",      // ← added by INodeLogger
  "traceId"    : "3d7f..."          // ← added by INodeLogger
}

PII in logs: Do not log customer names, email addresses, phone numbers, national ID numbers, or payment card details. Use reference IDs (orderId, customerId) in log messages. If you need PII for debugging, use the encrypted audit log API instead.

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