The OneCollectorExporter is designed for Microsoft products to send data to public-facing end-points which route to Microsoft's internal data pipeline. It is not meant to be used outside of Microsoft products and is open sourced to demonstrate best practices and to be transparent about what is being collected.

dotnet add package OpenTelemetry.Exporter.OneCollector

using var logFactory = LoggerFactory.Create(builder => builder
    .AddOpenTelemetry(builder =>
    {
        builder.IncludeScopes = true;
        builder.AddOneCollectorExporter("InstrumentationKey=instrumentation-key-here");
    }));

var logger = logFactory.CreateLogger<MyService>();

using var scope = logger.BeginScope("{requestContext}", Guid.NewGuid());

logger.LogInformation("Request received {requestId}!", 1);
logger.LogWarning("Warning encountered {error_code}!", 0xBAADBEEF);

By default when sending logs/events OneCollectorExporter generates fully qualified names using the LogRecord CategoryName and EventId.Name properties (ex: $"{CategoryName}.{EventId.Name}"). When EventId.Name is not supplied the OneCollectorLogExporterOptions.DefaultEventName property is used (the default value is Log). Event full names are used by the OneCollector service to create tables to store logs/events. The final table name may change casing and will change . characters to _ characters.

The default behavior is designed so that each unique log/event is mapped to its own table with its own schema. Attributes supplied on logs/events are promoted to columns on the table.

In the event that the default full name generation behavior does not result in the desired table configuration, EventFullNameMappings may be supplied to OneCollectorExporter to customize the final event full names sent to the OneCollector service.

Mappings can be specified using a default wild card rule, exact-match rules, and/or prefix-based (StartsWith) rules. In the event multiple prefix matches are made the one matching the most characters is selected.

• To change the default event full name for all logs add an entry with the key * and set the value to the desired event full name. Only a single * default entry may exist.

• To change the event full name for a specific namespace/category of log records add an entry with the key set to a prefix that will match from the starting portion of the namespace/category. Set the value to the desired event full name.

  For example, given the configuration...

  logging.AddOneCollectorExporter(
    "InstrumentationKey=instrumentation-key-here",
    builder => builder.SetEventFullNameMappings(
        new Dictionary<string, string>()
        {
            { "*", "DefaultLogs" },
            { "MyCompany", "InternalLogs" },
            { "MyCompany.Product1", "InternalProduct1Logs" },
            { "MyCompany.Product2", "InternalProduct2Logs" },
            { "MyCompany.Product2.Security", "InternalSecurityLogs" },
        });

  ...log event full name mapping would be performed as such:

  • ILogger<ThirdParty.Thing>: All logs emitted through this logger will use the "DefaultLogs" event full name

  • ILogger<MyCompany.ProductX.Thing>: All logs emitted through this logger will use the "InternalLogs" event full name

  • ILogger<MyCompany.Product1.Thing>: All logs emitted through this logger will use the "InternalProduct1Logs" event full name

  • ILogger<MyCompany.Product2.Thing>: All logs emitted through this logger will use the "InternalProduct2Logs" event full name

  • ILogger<MyCompany.Product2.Security.Alert>: All logs emitted through this logger will use the "InternalSecurityLogs" event full name

The default mapping behavior used by OneCollectorExporter is designed so that each unique log/event is mapped to its own table with its own schema. Using EventFullNameMappings may lead to many disparate logs/events with differing schema going into the same table. This could lead to wide tables with many columns or, in the case of logs/events sending attributes with the same name but different data types, lost or corrupt data.

OneCollectorExporter does not currently provide any features to automatically flatten or stringify attributes into a single column to prevent "schema explosion" issues as described above. Users are encouraged to manually stringify attributes which should not become columns into JSON strings and log them into a standard attribute:

logger.LogInformation(
    "Hello world {ColumnA} {ColumnB} {Attributes}",
    "A", // ColumnA
    "B", // ColumnB
    // Attributes:
    JsonSerializer.Serialize(
        new Dictionary<string, object?>()
        {
            ["id"] = 1,
            ["name"] = "name_goes_here",
        }));

Pass-through mappings that preserve the original event namespace and/or name are also possible.

For example, given the configuration...

logging.AddOneCollectorExporter(
   "InstrumentationKey=instrumentation-key-here",
   builder => builder.SetEventFullNameMappings(
       new Dictionary<string, string>()
       {
           { "*", "DefaultLogs" },
           { "MyCompany", "*" },
       });

...log event full name mapping would be performed as such:

• ILogger<ThirdParty.Thing>: All logs emitted through this logger will use the "DefaultLogs" event full name via the wild-card default rule.

• ILogger<MyCompany.OtherThing>: All logs emitted through this logger will have event full names generated as $"MyCompany.OtherThing.{EventId.Name}". OneCollectorLogExporterOptions.DefaultEventName is used (default value is Log) if a log/event does not have EventId.Name specified.