Add annotations and metadata to segments with the X-Ray SDK for .NET

You can use annotations and metadata to record additional information about requests, the environment, or your application. You can add annotations and metadata to the segments that the X-Ray SDK creates, or to custom subsegments that you create.

Annotations are key-value pairs with string, number, or Boolean values. Annotations are indexed for use with filter expressions. Use annotations to record data that you want to use to group traces in the console, or when calling the GetTraceSummaries API.

Metadata are key-value pairs that can have values of any type, including objects and lists, but are not indexed for use with filter expressions. Use metadata to record additional data that you want stored in the trace but don't need to use with search.

Recording annotations with the X-Ray SDK for .NET

Use annotations to record information on segments or subsegments that you want indexed for search.

The following are required for all annotations in X-Ray:

Annotation Requirements

• Keys – The key for an X-Ray annotation can have up to 500 alphanumeric characters. You cannot use spaces or symbols other than the underscore symbol (_).

• Values – The value for an X-Ray annotation can have up to 1,000 Unicode characters.

• The number of Annotations – You can use up to 50 annotations per trace.

To record annotations outside of a AWS Lambda function

1. Get an instance of AWSXRayRecorder.

   using Amazon.XRay.Recorder.Core;
   ...
   AWSXRayRecorder recorder = AWSXRayRecorder.Instance;

2. Call addAnnotation with a String key and a Boolean, Int32, Int64, Double, or String value.

   recorder.AddAnnotation("mykey", "my value");

To record annotations inside of a AWS Lambda function

Both segments and subsegments inside a Lambda function are managed by the Lambda runtime environment. If you want to add an annotation to a segment or subsegment inside a Lambda function, you must do the following:

1. Create the segment or subsegment inside the Lambda function.

2. Add the annotation to the segment or subsegment.

3. End the segment or subsegment.

The following code example shows you how to add an annotation to a subsegment inside a Lambda function:

#Create the subsegment
AWSXRayRecorder.Instance.BeginSubsegment("custom method");
#Add an annotation
AWSXRayRecorder.Instance.AddAnnotation("My", "Annotation");
try
{
  YourProcess(); #Your function
}
catch (Exception e)
{
  AWSXRayRecorder.Instance.AddException(e);
}
finally #End the subsegment
{
  AWSXRayRecorder.Instance.EndSubsegment();
}

The X-Ray SDK records annotations as key-value pairs in an annotations object in the segment document. Calling the addAnnotation operation twice with the same key overwrites a previously recorded value on the same segment or subsegment.

To find traces that have annotations with specific values, use the annotations.key keyword in a filter expression.

Recording metadata with the X-Ray SDK for .NET

Use metadata to record information on segments or subsegments that you don't need to index for use inside a search. Metadata values can be strings, numbers, booleans, or any other object that can be serialized into a JSON object or array.

To record metadata

1. Get an instance of AWSXRayRecorder, as shown in the following code example:

   using Amazon.XRay.Recorder.Core;
   ...
   AWSXRayRecorder recorder = AWSXRayRecorder.Instance;

2. Call AddMetadata with a string namespace, string key, and an object value, as shown in the following code example:

   recorder.AddMetadata("my namespace", "my key", "my value");

   You can also call the AddMetadata operation using just a key and value pair, as shown in the following code example:

   recorder.AddMetadata("my key", "my value");

If you don't specify a value for the namespace, the X-Ray SDK uses default. Calling the AddMetadata operation twice with the same key overwrites a previously recorded value on the same segment or subsegment.