IBM Cloud Functions runtime for swift

Simple swift action hello.swift

The traditional support for dictionary still works:

func main(args: [String:Any]) -> [String:Any] {
    if let name = args["name"] as? String {
        return [ "greeting" : "Hello \(name)!" ]
    } else {
        return [ "greeting" : "Hello swif4!" ]
    }
}

Packaging an action as a Swift executable using Swift 4

When you create an OpenWhisk Swift action with a Swift source file, it has to be compiled into a binary before the action is run. Once done, subsequent calls to the action are much faster until the container holding your action is purged. This delay is known as the cold-start delay.

To avoid the cold-start delay, you can compile your Swift file into a binary and then upload to OpenWhisk in a zip file. As you need the OpenWhisk scaffolding, the easiest way to create the binary is to build it within the same environment as it will be run in. These are the steps:

• Run an interactive Swift action container.

  docker run --rm -it -v "$(pwd):/owexec" ibmfunctions/action-swift-v4 bash
  

  This puts you in a bash shell within the Docker container.

• Copy the source code and prepare to build it.

  cp /owexec/hello.swift /swift4Action/spm-build/Sources/Action/main.swift
  

  cat /swift4Action/epilogue.swift >> /swift4Action/spm-build/Sources/Action/main.swift
  

  echo '_run_main(mainFunction:main)' >> /swift4Action/spm-build/Sources/Action/main.swift
  

  Copy any additional source files to /swift4Action/spm-build/Sources/Action/

• (Optional) Create the Package.swift file to add dependencies.

// swift-tools-version:4.0
// The swift-tools-version declares the minimum version of Swift required to build this package.

import PackageDescription

let package = Package(
    name: "Action",
    products: [
      .executable(
        name: "Action",
        targets:  ["Action"]
      )
    ],
    dependencies: [
      .package(url: "https://github.com/IBM-Swift/SwiftyRequest.git", .upToNextMajor(from: "1.0.0"))
    ],
    targets: [
      .target(
        name: "Action",
        dependencies: ["SwiftyRequest"],
        path: "."
      )
 

As you can see this example adds SwiftyRequest dependencies.

Notice that now with the new swift:4 runtime is no longer required to include the packages CCurl, Kitura-net or SwiftyJSON in your own Package.swift. You are free now to use no dependencies at all, or add the combination that you want with the versions you want.

• Copy Package.swift to spm-build directory

  cp /owexec/Package.swift /swift4Action/spm-build/Package.swift
  

• Change to the spm-build directory.

  cd /swift4Action/spm-build
  

• Compile your Swift Action.

  swift build -c release
  

• Create the zip archive.

  zip /owexec/hello.zip .build/release/Action
  

• Exit the Docker container.

  exit
  

  This has created hello.zip in the same directory as hello.swift.

• Upload it to OpenWhisk with the action name helloSwifty:

  wsk action update helloSwiftly hello.zip ibmfunctions/action-swift-v4
  

• To check how much faster it is, run

  wsk action invoke helloSwiftly --blocking
  

Migrating from Swift 3 to Swift 4

Helper compile.sh helper script

When compiling and packaging your swift 4 now there are a couple of differences All your source code needs to be copy to /swift4Action/spm-build/Sources/Action/ instead of /swift3Action/spm-build/ You Package.swift needs to have the first line with a comment indicating swift4 tooling and format

// swift-tools-version:4.0

For swift 4 you need specify additional information in Package.swift such as products with executable name Action and targets

You can take a look at the helper script tools/build/compile.sh to compile and zip your Actions. Having a project directory Hello under a directory actions like the following:

actions/Hello/Package.swift
actions/Hello/Sources/main.swift

Change to the parent directory then run the compile script specify the project directory, the kind swift:3.1.1 or swift:4 and any swiftc build flags like the following:

cd actions/
incubator-runtime-swift/tools/build/compile.sh Hello swift:4 -v

This will produce a zip build/swift4/Hello.zip

SwiftyJSON using single source action file

If you have a swift:3.1.1 action not compiled, meaning just as single source file using the SwiftyJSON package, you need to precompile your action and specify the version of SwiftyJSON you wan to use for swift:4 kind action. Take into account that tarting with Swift 4 there is better support to manage JSON data natively.

Note: This is only applicable to the base image provided for the Swift 4 runtime, other downstream such as IBM Cloud Functions extending this image might provide additional SDK and packages including SwiftyJSON and IBM Watson SDK, check the vendor documentation for more specific information about packages and versions.

Building the Swift4 Image

./gradlew swift4:distDocker

This will produce the image whisk/action-swift-v4

Login into Docker Client if not already authenticated

docker login

Build Image (Optional also push using dockerRegistry property)

./gradlew swift4:distDocker -PdockerRegistry=docker.io -PdockerImagePrefix=$DOCKER_USER -PdockerImageTag=${IMAGE_TAG:-"latest"}

Local development

Deploy OpenWhisk using ansible environment that contains the kind swift:4 Assuming you have OpenWhisk already deploy localy and OPENWHISK_HOME pointing to root directory of OpenWhisk core repository.

Set ROOTDIR to the root directory of this repository.

Redeploy OpenWhisk

cd $OPENWHISK_HOME/ansible
ANSIBLE_CMD="ansible-playbook -i ${ROOTDIR}/ansible/environments/local"
$ANSIBLE_CMD setup.yml
$ANSIBLE_CMD couchdb.yml
$ANSIBLE_CMD initdb.yml
$ANSIBLE_CMD wipe.yml
$ANSIBLE_CMD openwhisk.yml

Or you can use wskdev and create a soft link to the target ansible environment, for example:

ln -s ${ROOTDIR}/ansible/environments/local ${OPENWHISK_HOME}/ansible/environments/local-swift
${OPENWHISK_HOME}/wskdev fresh -t local-swift

To use as docker action push to your own dockerhub account

docker tag whisk/action-swift-v4n $user_prefix/action-swift-v4
docker push $user_prefix/action-swift-v4

Then create the action using your the image from dockerhub

wsk action update myAction myAction.swift --docker $user_prefix/action-swift-v4

The $user_prefix is usually your dockerhub user id.

License

Apache 2.0