Soto for AWS

Soto is a Swift language SDK for Amazon Web Services (AWS), working on Linux, macOS and iOS. This library provides access to all AWS services. The service APIs it provides are a direct mapping of the REST APIs Amazon publishes for each of its services. Soto is a community supported project and is in no way affiliated with AWS.

If you are looking for the documentation for v5 you can find it here.

Compatibility

Soto works on Linux, macOS and iOS. Version 4 is dependent on swift-nio 2. Libraries/frameworks that are dependent on an earlier version of swift-nio will not work with version 4 of Soto. In this case Version 3 can be used. For example Vapor 3 uses swift-nio 1.13 so you can only use versions 3.x of Soto with Vapor 3. Below is a compatibility table for versions 3 and 4 of Soto.

Documentation

Visit the Soto documentation to browse the api reference.

Installation

Swift Package Manager

Soto uses the Swift Package Manager to manage its code dependencies. To use Soto in your codebase it is recommended you do the same. Add a dependency to the package in your own Package.swift dependencies.

    dependencies: [
        .package(url: "https://github.com/soto-project/soto.git", from: "4.0.0")
    ],

Then add target dependencies for each of the Soto targets you want to use.

    targets: [
      .target(name: "MyAWSApp", dependencies: ["S3", "SES", "CloudFront", "ELBV2", "IAM", "Kinesis"]),
    ]
)

Alternatively if you are using Xcode 11+ you can use the Swift Package integration and add a dependency to Soto through that.

Configuring Credentials

Before using the SDK, you will need AWS credentials to sign all your requests. Credentials can be provided in the following ways.

Via EC2 Instance Profile

If you are running your code on an AWS EC2 instance, you can setup an IAM role as the server’s Instance Profile to automatically grant credentials via the metadata service.

There are no code changes or configurations to specify in the code, it will automatically pull and use them.

Via ECS Container credentials

If you are running your code as an AWS ECS container task, you can setup an IAM role for your container task to automatically grant credentials via the metadata service.

There are no code changes or configurations to specify in the code, it will automatically pull and use them.

Load Credentials from shared credential file.

You can set shared credentials in the home directory for the user running the app

in ~/.aws/credentials,

[default]
aws_access_key_id = YOUR_AWS_ACCESS_KEY_ID
aws_secret_access_key = YOUR_AWS_SECRET_ACCESS_KEY

Load Credentials from Environment Variable

Alternatively, you can set the following environment variables:

AWS_ACCESS_KEY_ID=YOUR_AWS_ACCESS_KEY_ID
AWS_SECRET_ACCESS_KEY=YOUR_AWS_SECRET_ACCESS_KEY

Pass the Credentials to the AWS Service struct directly

All of the AWS Services’s initializers accept accessKeyId and secretAccessKey

let ec2 = EC2(
    accessKeyId: "YOUR_AWS_ACCESS_KEY_ID",
    secretAccessKey: "YOUR_AWS_SECRET_ACCESS_KEY"
)

Without Credentials

Some services like CognitoIdentityProvider don’t require credentials to access some of their functions. Explicitly set accessKeyId and secretAccessKey to “”. This will disable all other credential access functions and send requests unsigned.

Using Soto

AWS Swift Modules can be imported into any swift project. Each module provides a struct that can be initialized, with instance methods to call aws services. See documentation for details on specific services.

The underlying Soto httpclient returns a swift-nio EventLoopFuture object. An EventLoopFuture is not the response, but rather a container object that will be populated with the response sometime later. In this manner calls to AWS do not block the main thread.

The recommended manner to interact with futures is chaining. The following function returns an EventLoopFuture that creates an S3 bucket, puts a file in the bucket, reads the file back from the bucket and finally prints the contents of the file. Each of these operations are chained together. The output of one being the input of the next.

import S3 //ensure this module is specified as a dependency in your package.swift

let bucket = "my-bucket"

let s3 = S3(accessKeyId: "Your-Access-Key", secretAccessKey: "Your-Secret-Key", region: .uswest2)

func createBucketPutGetObject() -> EventLoopFuture<S3.GetObjectOutput> {
    // Create Bucket, Put an Object, Get the Object
    let createBucketRequest = S3.CreateBucketRequest(bucket: bucket)

    s3.createBucket(createBucketRequest)
        .flatMap { response -> EventLoopFuture<S3.PutObjectOutput> in
            // Upload text file to the s3
            let bodyData = "hello world".data(using: .utf8)!
            let putObjectRequest = S3.PutObjectRequest(acl: .publicRead, body: bodyData, bucket: bucket, contentLength: Int64(bodyData.count), key: "hello.txt")
            return s3.putObject(putObjectRequest)
        }
        .flatMap { response -> EventLoopFuture<S3.GetObjectOutput> in
            let getObjectRequest = S3.GetObjectRequest(bucket: bucket, key: "hello.txt")
            return s3.getObject(getObjectRequest)
        }
        .whenSuccess { response in
            if let body = response.body {
                print(String(data: body, encoding: .utf8)!)
            }
    }
}

upgrading from <3.0.x

The simplest way to upgrade from an existing 1.0 or 2.0 implementation is to call .wait() on existing synchronous calls. However it is recommend to rewrite your synchronous code to work with the returned future objects. It is no longer necessary to use a DispatchQueue.

EventLoopGroup management

Soto has its own EventLoopGroup but it is recommended that you provide your own EventLoopGroup for the SDK to work off. You can do this when you construct your client.

let s3 = S3(region:.uswest2, eventLoopGroupProvider: .shared(myEventLoopGroup)

The EventLoopGroup types you can use depend on the platform you are running on. On Linux use MultiThreadedEventLoopGroup, on macOS use MultiThreadedEventLoopGroup or NIOTSEventLoopGroup and iOS use NIOTSEventLoopGroup. Using the NIOTSEventLoopGroup will mean you use NIO Transport Services and the Apple Network framework.

Using Soto with Vapor

Integration with Vapor is pretty straight forward. Although be sure you use the correct version of Soto depending on which version of Vapor you are using. See the compatibility section for details. Below is a simple Vapor 3 example that extracts an email address, subject and message from a request and then sends an email using these details. Take note of the hopTo(eventLoop:) call. If your AWS SDK is not working off the same EventLoopGroup as the Vapor Request this is a requirement.

import Vapor
import HTTP
import SES

final class MyController {
    struct EmailData: Content {
        let address: String
        let subject: String
        let message: String
    }
    func sendUserEmailFromJSON(_ req: Request) throws -> EventLoopFuture<HTTPStatus> {
        return try req.content.decode(EmailData.self)
            .flatMap { (emailData)->EventLoopFuture<SES.SendEmailResponse> in
                let client = SES(region: .uswest1)

                let destination = SES.Destination(toAddresses: [emailData.address])
                let message = SES.Message(body:SES.Body(text:SES.Content(data:emailData.message)), subject:SES.Content(data:emailData.subject))
                let sendEmailRequest = SES.SendEmailRequest(destination: destination, message: message, source:"soto@me.com")

                return client.sendEmail(sendEmailRequest)
            }
            .hopTo(eventLoop: req.eventLoop)
            .map { response -> HTTPResponseStatus in
                return HTTPStatus.ok
        }
    }
}