Swift 5 - Ubuntu Docker

This repo contains the code for generating two Docker images for Swift:

• The ibmcom/swift-ubuntu image contains the Swift 5.0.2 RELEASE toolchain as well as the dependencies for running Kitura-based applications. Our development team uses this image for development and testing of Swift 5 applications on the Linux Ubuntu (v14.04) operating system.

• The ibmcom/swift-ubuntu-runtime image contains only those libraries (.so files) provided by the Swift 5.0.2 RELEASE toolchain that are required to run Swift applications. Note that this image does not contain SwiftPM or any of the build tools used when compiling and linking Swift applications. Hence, the size for the ibmcom/swift-ubuntu-runtime image (~300 MB) is much smaller than that of the ibmcom/swift-ubuntu image. The ibmcom/swift-ubuntu-runtime image is ideal for provisioning your Swift application as an IBM Container on the IBM Cloud.

• The ibmcom/swift-ubuntu-xenial and ibmcom/swift-ubuntu-xenial-runtime images follow a similar convention, but for Linux Ubuntu 16.04. These images are multi-arch so will pull down the appropriate image for your architecture. We currently offer support for amd64 and s390x architectures.

Recent updates

1. Upgraded to the Swift 5.0.2 RELEASE binaries.
2. Changed location of Swift binaries and libraries so they are available system wide (not just for the root user).
3. Reduced number of layers in images.
4. Removed system packages no longer needed.
5. Aligned version of Ubuntu with version found in Cloud Foundry environments (v14.04).
6. Reduced size of the Docker image.
7. Updated Dockerfiles per guidelines in Best practices for writing Dockerfiles.
8. Added Support for amd64 and s390x architectures of Xenial Linux Ubuntu 16.04.

Quick Start

The easiest way to get started is by using the Kitura command line tools to generate the docker files needed, and copy them over to your project. If you just want to explore our supported base images, see the next sections.

To get started with kitura init:

1. Create a new directory, change into it and run kitura init. This will generate a project which will include two files named Dockerfile and Dockerfile-tools.
2. Copy the Dockerfile and Dockerfile-tools files into your project's root directory (this is the directory that contains your Package.swift file and the Sources and Tests folders).
3. Edit the Dockerfile in a text editor and replace references to your kitura init folder with the name of your project. Dockerfile-Tools has preconfigured behavior to download and compile Swift binaries and copy the executable into your application. It doesn't need editing.
4. Run the following commands, replacing YOUR_PROJECT with the name of your project. Note: Use all lower case letters for your projects name and replace spaces with dashes.
   1. docker build -t YOUR_PROJECT-build -f Dockerfile-tools .
   2. docker run -v $PWD:/root/project -w /root/project YOUR_PROJECT-build /swift-utils/tools-utils.sh build release
   3. docker run -it -p 8090:8080 -v $PWD:/root/project -w /root/project YOUR_PROJECT-run sh -c ".build-ubuntu/release/YOUR_PROJECT"

Dockerfile-tools is responsible for downloading the Swift binaries and builds the exectuables.

The Dockerfile then copies the applications source code, and then compiled executable into the runtime image of the application. This means the large Swift binary file isn't copied into your application, and reduces the overall size of your app, meaning faster uploads and a smaller storage quota impact.

The final command runs your Docker image locally.

This was the quickest way to get started, but if you just want see explore our base images then see the following sections for detailed instructions.

ibmcom/swift-ubuntu

Pulling ibmcom/swift-ubuntu from Docker Hub

Run the following command to download the latest version of the ibmcom/swift-ubuntu image from Docker Hub:

docker pull ibmcom/swift-ubuntu:latest

Use a specific version of ibmcom/swift-ubuntu

Docker images are tagged with Swift version number. To use the Swift 5.0.2 image from Docker Hub, issue the following command:

docker pull ibmcom/swift-ubuntu:5.0.2

Using ibmcom/swift-ubuntu for development

Mount a folder on your host to your Docker container using the following command:

docker run -i -t -v <absolute path to the swift package>:/<swift package name> ibmcom/swift-ubuntu:5.0.2

After executing the above command, you will have terminal access to the Docker container (the default command for the image is /bin/bash). This will allow you to build, test, and run your Swift application in a Linux environment (Ubuntu v14.04).

Privileged mode

If you attempt to run the Swift REPL and you get the error failed to launch REPL process: process launch failed: 'A' packet returned an error: 8, then you should run your Docker container in privileged mode:

docker run --privileged -i -t ibmcom/swift-ubuntu:5.0.2

This issue is described at https://bugs.swift.org/browse/SR-54.

ibmcom/swift-ubuntu-xenial

Pulling ibmcom/swift-ubuntu-xenial from Docker Hub

Run the following command to download the latest version of the ibmcom/swift-ubuntu-xenial image from Docker Hub:

docker pull ibmcom/swift-ubuntu-xenial:latest

This image supports both amd64 and s390x architectures and will pull down the correct image based on the architecture you are using i.e. ibmcom/swift-ubuntu-xenial-amd64 or ibmcom/swift-ubuntu-xenial-s390x.

Using ibmcom/swift-ubuntu-xenial for development

Mount a folder on your host to your Docker container using the following command:

docker run -i -t -v <absolute path to the swift package>:/<swift package name> ibmcom/swift-ubuntu-xenial:latest

After executing the above command, you will have terminal access to the Docker container (the default command for the image is /bin/bash). This will allow you to build, test, and run your Swift application in a Linux environment (Ubuntu v16.04, amd64 or s390x), depending on your architecture.

Privileged mode

If you attempt to run the Swift REPL and you get the error failed to launch REPL process: process launch failed: 'A' packet returned an error: 8, then you should run your Docker container in privileged mode:

docker run --privileged -i -t ibmcom/swift-ubuntu-xenial:latest

This issue is described at https://bugs.swift.org/browse/SR-54.

ibmcom/swift-ubuntu-runtime

Pulling ibmcom/swift-ubuntu-runtime from Docker Hub

Run the following command to download the latest version of the ibmcom/swift-ubuntu-runtime image from Docker Hub:

docker pull ibmcom/swift-ubuntu-runtime:latest

Use a specific version of ibmcom/swift-ubuntu-runtime

Docker images are now tagged with Swift version number. To use the Swift 5.0.2 image from Docker Hub, issue the following command:

docker pull ibmcom/swift-ubuntu-runtime:5.0.2

Using ibmcom/swift-ubuntu-runtime

You can extend the ibmcom/swift-ubuntu-runtime image in your own Dockerfile to add your Swift application binaries (and any other dependencies you may need). For instance, the next sample Dockerfile simply adds the binaries for the Kitura-Starter application and specifies the command to start the server (total image size after adding the Kitura-Starter binaries is ~300MB):

# Builds a Docker image for running the Kitura-Starter sample application.

...

FROM ibmcom/swift-ubuntu-runtime:5.0.2
LABEL Description="Docker image for running the Kitura-Starter sample application."

USER root

# Expose default port for Kitura
EXPOSE 8080

# Binaries should have been compiled against the correct platform (i.e. Ubuntu 14.04).
RUN mkdir /Kitura-Starter
ADD .build/debug/Kitura-Starter /Kitura-Starter
ADD .build/debug/*.so /Kitura-Starter
ADD .build/debug/*.so.* /Kitura-Starter
CMD [ "sh", "-c", "/Kitura-Starter/Kitura-Starter" ]

For details on how to create an IBM Container to execute a Swift application, please see 10 Steps To Running a Swift App in an IBM Container and Running Kitura in an IBM Container.

Exposing ports in your Docker container

Exposing your server's port running in a Docker container to the host system (e.g. macOS) is quite easy using the latest version of Docker:

docker run -p <host port>:<container port> [additional options] <image name>

For example, if your Swift server is running on port 8080, and you want to make it accessible via port 9080 on the host system, run the following command:

docker run -p 9080:8080 [additional options] <image name>

Port 8080 in the container will then be mapped to port 9080 on the host system. For further details on the -p option, see the official Docker documentation.

Contributing

Improvements are very welcome! You can find more info on contributing in our contributing guidelines.