aws-sdk-swift-usage - SKILL.md Agent Skill

name: aws-sdk-swift-usage description: | AWS SDK for Swift development patterns. Use when writing Swift code that uses AWS services via aws-sdk-swift package.

AWS SDK for Swift

Async Code Structure

All SDK operations are async. Use @main entry point:

@main
struct Main {
    static func main() async throws {
        let client = try await S3Client()
        // ... async operations
    }
}

CRITICAL: Use Struct Config Types

NEVER use S3ClientConfiguration or DynamoDBClientConfiguration - these are DEPRECATED classes.

ALWAYS use the struct-based config types:

S3Client.S3ClientConfig (not S3ClientConfiguration)
DynamoDBClient.DynamoDBClientConfig (not DynamoDBClientConfiguration)
STSClient.STSClientConfig (not STSClientConfiguration)

Config parameters MUST be in declaration order. Region is ALWAYS required when creating a config. Check the service client source for exact order.

// CORRECT - struct config
let config = try await S3Client.S3ClientConfig(region: "us-west-2")
let client = S3Client(config: config)

// WRONG - deprecated class
// let config = try await S3Client.S3ClientConfiguration(region: "us-west-2")

Client Creation

All service clients follow the same pattern: <Service>Client with <Service>Client.<Service>ClientConfig.

Model types (structs/enums used in requests/responses) are namespaced under <Service>ClientTypes:

S3ClientTypes.Bucket, S3ClientTypes.Object
DynamoDBClientTypes.AttributeValue
CloudWatchClientTypes.MetricDatum, CloudWatchClientTypes.Dimension

import AWSS3
import AWSDynamoDB

// Simple - auto-detects region
let s3 = try await S3Client()
let dynamo = try await DynamoDBClient()

// With region
let s3 = try S3Client(region: "us-west-2")

// With config - parameters must be in declaration order
let config = try await S3Client.S3ClientConfig(
    useFIPS: true,
    awsRetryMode: .adaptive,
    maxAttempts: 5,
    region: "us-west-2"
)
let client = S3Client(config: config)

// With custom endpoint and credentials
let config = try await S3Client.S3ClientConfig(
    awsCredentialIdentityResolver: resolver,
    region: "us-west-2",
    endpoint: "https://s3.custom-endpoint.com"
)

Common config parameters (MUST follow declaration order):

awsCredentialIdentityResolver - Custom credentials
useFIPS - Enable FIPS endpoints
useDualStack - Enable dual-stack endpoints
awsRetryMode - Retry strategy (.adaptive, .standard, .legacy)
maxAttempts - Max retry attempts
region - AWS region

httpClientEngine - Custom HTTP client (requires HttpClientConfiguration parameter):

import ClientRuntime
let httpConfig = HttpClientConfiguration()
let httpClient = URLSessionHTTPClient(httpClientConfiguration: httpConfig)
let config = try await S3Client.S3ClientConfig(
    region: "us-east-1",
    httpClientEngine: httpClient
)

endpoint - Custom endpoint URL

For service-specific config options or exact parameter order, check Sources/Services/AWS<Service>/Sources/AWS<Service>/<Service>Client.swift in the SDK.

Credential Resolvers

import AWSSDKIdentity
import SmithyIdentity

// Static credentials - pass credential object directly
let creds = AWSCredentialIdentity(accessKey: "AKIA...", secret: "...")
let resolver = StaticAWSCredentialIdentityResolver(creds)

// Assume role - REQUIRES underlying resolver
let underlying = try DefaultAWSCredentialIdentityResolverChain()
let resolver = try STSAssumeRoleAWSCredentialIdentityResolver(
    awsCredentialIdentityResolver: underlying,
    roleArn: "arn:aws:iam::123456789012:role/MyRole",
    sessionName: "session-name"
)

// Use in config
let config = try await S3Client.S3ClientConfig(
    awsCredentialIdentityResolver: resolver,
    region: "us-west-2"
)

Waiters

Import SmithyWaitersAPI. WaiterOptions requires maxWaitTime parameter:

import AWSS3
import SmithyWaitersAPI

let client = try await S3Client()
_ = try await client.waitUntilBucketExists(
    options: WaiterOptions(maxWaitTime: 120.0),
    input: HeadBucketInput(bucket: "my-bucket")
)

Pagination

let input = ListObjectsV2Input(bucket: "my-bucket")
for try await page in client.listObjectsV2Paginated(input: input) {
    for object in page.contents ?? [] {
        print(object.key ?? "")
    }
}

Presigned URLs

let url = try await client.presignedURLForGetObject(
    input: GetObjectInput(bucket: "my-bucket", key: "file.pdf"),
    expiration: 3600
)

Common Operations

// Put object
_ = try await client.putObject(input: PutObjectInput(
    body: .data(data),
    bucket: "bucket",
    key: "key"
))

// Get object
let output = try await client.getObject(input: GetObjectInput(bucket: "bucket", key: "key"))
let data = try await output.body?.readData()

// List buckets
let response = try await client.listBuckets(input: ListBucketsInput())
for bucket in response.buckets ?? [] {
    print(bucket.name ?? "")
}