AWS rules engine library functions

AWS-specific rules engine library functions make it possible to integrate AWS concepts like Amazon Resource Names (ARNs) and Partitions. An additional dependency is required to access these functions:

The following example adds smithy-aws-endpoints as a dependency to a Smithy project:

Smithy CLI

smithy-build.json

{
    "maven": {
        "dependencies": [
            "software.amazon.smithy:smithy-aws-endpoints:1.65.0"
        ]
    }
}

Gradle

Kotlin

build.gradle.kts

dependencies {
    ...
    implementation("software.amazon.smithy:smithy-aws-endpoints:1.65.0")
    ...
}

Groovy

build.gradle

dependencies {
    ...
    implementation 'software.amazon.smithy:smithy-aws-endpoints:1.65.0'
    ...
}

aws.partition function

Summary

Provides a Partition structure of content for the

Argument type

• region: string

Return type

option<Partition>

Contains the region's partition, or an empty optional if the region is unknown.

The following example uses aws.partition to provide partition information from the region in the value of the foo parameter:

{
    "fn": "aws.partition",
    "argv": [
        {"ref": "foo"}
    ]
}

Partition structure

The Partition structure is returned from the aws.partition function when its input is a known region. The Partition object contains the following properties:

Property	Type	Description
name	string	The partition's name.
dnsSuffix	string	The partition's default DNS suffix.
dualStackDnsSuffix	string	The partition's dual-stack specific DNS suffix.
supportsFIPS	bool	Indicates whether the partition supports a FIPS compliance mode.
supportsDualStack	bool	Indicates whether the partition supports dual-stack endpoints.
implicitGlobalRegion	string	The region used by partitional (non-regionalized/global) services for signing.

aws.parseArn function

Summary

Computes an ARN structure given an input string.

Argument type

• value: string

Return type

option<ARN>

Contains the parsed ARN, or an empty optional if the ARN could not be parsed

The following example uses aws.parseArn to parse the value of the foo parameter into its component parts:

{
    "fn": "aws.parseArn",
    "argv": [
        {"ref": "foo"}
    ]
}

ARN structure

The ARN structure is returned from the aws.parseArn function when its input is a valid ARN. The ARN object contains the following properties:

Property	Type	Description
partition	string	The partition where the resource is located.
service	string	The service namespace where the resource is located.
region	string	The region where the resource is located. May be an empty length value if the resource is not region-based.
accountId	string	The account that the resource is managed by. May be an empty length value if the resource is not account-based.
resourceId	array<string>	An array of resourceId components, where the final segment of the ARN is split on : and / characters.

Examples

The following table shows valid and invalid values for an input to the aws.parseArn function:

Input	Valid?	partition	service	region	accountId	resourceId
arn:aws:sns:us-west-2:012345678910:example-sns-topic-name	true	aws	sns	us-west-2	012345678910	example-sns-topic-name
11111111-2222-3333-4444-555555555555	false
arn:aws:ec2:us-east-1:012345678910:vpc/vpc-0e9801d129EXAMPLE	true	aws	ec2	us-east-1	012345678910	[vpc, vpc-0e9801d129EXAMPLE]
arn:aws:iam::012345678910:user/johndoe	true	aws	iam	An empty string.	012345678910	[user, johndoe]
arn:aws:s3:::bucket_name	true	aws	s3	An empty string.	An empty string.	bucket_name

aws.isVirtualHostableS3Bucket function

Summary

Evaluates whether the input string is a compliant RFC 1123 host segment and contains a segment that is a valid bucket name. When allowSubDomains is true, evaluates whether the input string is composed of values that are each compliant values joined by dot (.) characters.

Argument type

• value: string

• allowSubDomains: bool

Return type

bool

The following example uses aws.isVirtualHostableS3Bucket to check if the value of the foo parameter is an RFC 1123 compliant host segment and a valid bucket name.

{
    "fn": "aws.isVirtualHostableS3Bucket",
    "argv": [
        {"ref": "foo"},
        false
    ]
}