﻿---
title: Manual log correlation
description: If the agent-provided logging integrations are not suitable or not available for your application, then you can use the agent’s API to inject trace IDs...
url: https://www.elastic.co/elastic/docs-builder/docs/2870/reference/apm/agents/dotnet/log-correlation-manual
products:
  - APM .NET Agent
  - APM Agent
applies_to:
  - Serverless Observability projects: Generally available
  - Elastic Stack: Generally available
  - Application Performance Monitoring Agent for .NET: Generally available
---

# Manual log correlation
If the agent-provided logging integrations are not suitable or not available for your application, then you can use the agent’s [API](https://www.elastic.co/elastic/docs-builder/docs/2870/reference/apm/agents/dotnet/public-api) to inject trace IDs manually. There are two main approaches you can take, depending on whether you are using structured or unstructured logging.

## Manual log correlation (structured)

For correlating structured logs with traces, the following fields should be added to your logs:
- `trace.id`
- `transaction.id`

Given a transaction object, you can obtain its trace id by using the `Transaction.TraceId` property and its transaction id by using the `Transaction.Id` property.
You can also use the [Elastic.Apm.Agent.Tracer.CurrentTransaction](/elastic/docs-builder/docs/2870/reference/apm/agents/dotnet/public-api#api-current-transaction) property anywhere in the code to access the currently active transaction.
```csharp
public (string traceId, string transactionId) GetTraceIds()
{
	if (!Agent.IsConfigured) return default;
	if (Agent.Tracer.CurrentTransaction == null) return default;
	return (Agent.Tracer.CurrentTransaction.TraceId, Agent.Tracer.CurrentTransaction.Id);
}
```

In case the agent is configured and there is an active transaction, the `traceId` and `transactionId` will always return the current trace and transaction ids that you can manually add to your logs. Make sure you store those in the fields `trace.id` and `transaction.id` when you send them to Elasticsearch.

## Manual log correlation (unstructured)

For correlating unstructured logs (e.g. basic printf-style logging, like `Console.WriteLine`), you will need to include the trace ids in your log message, and then extract them using Filebeat.
If you already have a transaction object, then you can use the `TraceId` and `Id` properties. Both are of type `string`, so you can simply add them to the log.
```csharp
var currentTransaction = //Get Current transaction, e.g.: Agent.Tracer.CurrentTransaction;

Console.WriteLine($"ERROR [trace.id={currentTransaction.TraceId} transaction.id={currentTransaction.Id}] an error occurred");
```

This would print a log message along the lines of:
```
    ERROR [trace.id=cd04f33b9c0c35ae8abe77e799f126b7 transaction.id=cd04f33b9c0c35ae] an error occurred
```

For log correlation to work, the trace ids must be extracted from the log message and stored in separate fields in the Elasticsearch document. This can be achieved by [parsing the data by using ingest node](https://docs-v3-preview.elastic.dev/elastic/docs-builder/docs/2870/reference/beats/filebeat/configuring-ingest-node), in particular by using [the grok processor](https://docs-v3-preview.elastic.dev/elastic/docs-builder/docs/2870/reference/enrich-processor/grok-processor).
```json
{
  "description": "...",
  "processors": [
    {
      "grok": {
        "field": "message",
        "patterns": [%{LOGLEVEL:log.level} \\[trace.id=%{TRACE_ID:trace.id}(?: transaction.id=%{SPAN_ID:transaction.id})?\\] %{GREEDYDATA:message}"],
        "pattern_definitions": {
          "TRACE_ID": "[0-9A-Fa-f]{32}",
          "SPAN_ID": "[0-9A-Fa-f]{16}"
        }
      }
    }
  ]
}
```