# SamplingRule
<a name="API_SamplingRule"></a>

A sampling rule that services use to decide whether to instrument a request. Rule fields can match properties of the service, or properties of a request. The service can ignore rules that don't match its properties.

## Contents
<a name="API_SamplingRule_Contents"></a>

 ** FixedRate **   <a name="xray-Type-SamplingRule-FixedRate"></a>
The percentage of matching requests to instrument, after the reservoir is exhausted.  
Type: Double  
Valid Range: Minimum value of 0. Maximum value of 1.  
Required: Yes

 ** Host **   <a name="xray-Type-SamplingRule-Host"></a>
Matches the hostname from a request URL.  
Type: String  
Length Constraints: Maximum length of 64.  
Required: Yes

 ** HTTPMethod **   <a name="xray-Type-SamplingRule-HTTPMethod"></a>
Matches the HTTP method of a request.  
Type: String  
Length Constraints: Maximum length of 10.  
Required: Yes

 ** Priority **   <a name="xray-Type-SamplingRule-Priority"></a>
The priority of the sampling rule.  
Type: Integer  
Valid Range: Minimum value of 1. Maximum value of 9999.  
Required: Yes

 ** ReservoirSize **   <a name="xray-Type-SamplingRule-ReservoirSize"></a>
A fixed number of matching requests to instrument per second, prior to applying the fixed rate. The reservoir is not used directly by services, but applies to all services using the rule collectively.  
Type: Integer  
Valid Range: Minimum value of 0.  
Required: Yes

 ** ResourceARN **   <a name="xray-Type-SamplingRule-ResourceARN"></a>
Matches the ARN of the AWS resource on which the service runs.  
Type: String  
Length Constraints: Maximum length of 500.  
Required: Yes

 ** ServiceName **   <a name="xray-Type-SamplingRule-ServiceName"></a>
Matches the `name` that the service uses to identify itself in segments.  
Type: String  
Length Constraints: Maximum length of 64.  
Required: Yes

 ** ServiceType **   <a name="xray-Type-SamplingRule-ServiceType"></a>
Matches the `origin` that the service uses to identify its type in segments.  
Type: String  
Length Constraints: Maximum length of 64.  
Required: Yes

 ** URLPath **   <a name="xray-Type-SamplingRule-URLPath"></a>
Matches the path from a request URL.  
Type: String  
Length Constraints: Maximum length of 128.  
Required: Yes

 ** Version **   <a name="xray-Type-SamplingRule-Version"></a>
The version of the sampling rule format (`1`).  
Type: Integer  
Valid Range: Minimum value of 1.  
Required: Yes

 ** Attributes **   <a name="xray-Type-SamplingRule-Attributes"></a>
Matches attributes derived from the request.  
Type: String to string map  
Map Entries: Maximum number of 5 items.  
Key Length Constraints: Minimum length of 1. Maximum length of 32.  
Value Length Constraints: Minimum length of 1. Maximum length of 32.  
Required: No

 ** RuleARN **   <a name="xray-Type-SamplingRule-RuleARN"></a>
The ARN of the sampling rule. Specify a rule by either name or ARN, but not both.  
Type: String  
Required: No

 ** RuleName **   <a name="xray-Type-SamplingRule-RuleName"></a>
The name of the sampling rule. Specify a rule by either name or ARN, but not both.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 32.  
Required: No

 ** SamplingRateBoost **   <a name="xray-Type-SamplingRule-SamplingRateBoost"></a>
Specifies the multiplier applied to the base sampling rate. This boost allows you to temporarily increase sampling without changing the rule's configuration.  
Type: [SamplingRateBoost](API_SamplingRateBoost.md) object  
Required: No

## See Also
<a name="API_SamplingRule_SeeAlso"></a>

For more information about using this API in one of the language-specific AWS SDKs, see the following:
+  [AWS SDK for C\$1\$1](https://docs.aws.amazon.com/goto/SdkForCpp/xray-2016-04-12/SamplingRule) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/xray-2016-04-12/SamplingRule) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/xray-2016-04-12/SamplingRule)