Android SDK build scripts

[marcprux]

Following up on swiftlang/github-workflows#106 and swiftlang/swift#80788, this PR contains a new swift-docker/swift-ci/sdks/android/ folder with scripts that will build and upload a full stand-alone Swift Android Swift SDK. It is modeled after the structure of the swift-ci/sdks/static-linux build scripts.

Running

The top-level ./build script installs a host toolchain and the Android NDK, and then invokes scripts/fetch-source.sh which will fetch tagged sources for libxml2, curl, boringssl, and swift.

It then applies some patches and invokes scripts/build.sh, which will build the sources for each of the specified architectures. Finally, it combines the NDK and the newly built SDKs into a single artifactbundle.

Specifying Architectures

By default all the supported Android architectures (aarch64, x86_64, aarmv7) will be built, but this can be reduced in order to speed up the build. This can be useful, e.g., as part of a CI that validates a pull request, as building a single architecture takes around 30 minutes on a standard ubuntu-24.04 GitHub runner, whereas building for all the architectures takes over an hour.

To build an artifactbundle for just the x86_64 architecture, run:

TARGET_ARCHS=x86_64 ./build

Installing and validating the SDK

The .github/workflows/pull_request.yml workflow will create and upload an installable SDK named something like: swift-6.1-RELEASE_android-0.1.artifactbundle.tar.gz. The results of one of the workflow runs can be seen at https://github.com/swift-android-sdk/swift-docker/actions/runs/14603885089

The workflow will also install the SDK locally and use swift-android-action to build and test various Swift packages in an Android emulator.

[marcprux]

I've updated this PR to build the SDK without including the Android NDK. In order to accommodate this, there is now a post-install scripts/setup-android-sdk.sh that will need to be run manually after the swift sdk install … command. This will find the NDK based on the standard ANDROID_NDK_HOME environment variable and create links from the NDK into the path specified by swift-sdk.json's sdkRootPath, as well as pulling in the swiftrt.o to work around swiftlang/swift#79621.

The latest result of the build for the 6.2 nightly can be seen at: https://github.com/skiptools/swift-android-toolchain/releases/tag/6.2-DEVELOPMENT-SNAPSHOT-2025-05-07-a

[marcprux]

To clarify what the post-install script is doing, following is a result of the output of the command with the default NDK directory:

zap org.swift.swiftpm/swift-sdks % tree swift-6.2-DEVELOPMENT-SNAPSHOT-2025-05-07-a-android-0.1.artifactbundle/swift-android/ndk-sysroot
└── usr
    ├── include -> ~/Library/Android/sdk/ndk/27.0.12077973/toolchains/llvm/prebuilt/darwin-x86_64/sysroot/usr/include
    └── lib
        ├── aarch64-linux-android -> ~/Library/Android/sdk/ndk/27.0.12077973/toolchains/llvm/prebuilt/darwin-x86_64/sysroot/usr/lib/aarch64-linux-android
        ├── arm-linux-androideabi -> ~/Library/Android/sdk/ndk/27.0.12077973/toolchains/llvm/prebuilt/darwin-x86_64/sysroot/usr/lib/arm-linux-androideabi
        ├── x86_64-linux-android -> ~/Library/Android/sdk/ndk/27.0.12077973/toolchains/llvm/prebuilt/darwin-x86_64/sysroot/usr/lib/x86_64-linux-android
        ├── swift
        │   └── android
        │       ├── aarch64
        │       │   └── swiftrt.o -> ../../../../../../swift-resources/usr/lib/swift-aarch64/android/aarch64/swiftrt.o
        │       ├── armv7
        │       │   └── swiftrt.o -> ../../../../../../swift-resources/usr/lib/swift-armv7/android/armv7/swiftrt.o
        │       └── x86_64
        │           └── swiftrt.o -> ../../../../../../swift-resources/usr/lib/swift-x86_64/android/x86_64/swiftrt.o
        └── swift_static
            └── android
                ├── aarch64
                │   └── swiftrt.o -> ../../../../../../swift-resources/usr/lib/swift_static-aarch64/android/aarch64/swiftrt.o
                ├── armv7
                │   └── swiftrt.o -> ../../../../../../swift-resources/usr/lib/swift_static-armv7/android/armv7/swiftrt.o
                └── x86_64
                    └── swiftrt.o -> ../../../../../../swift-resources/usr/lib/swift_static-x86_64/android/x86_64/swiftrt.o

Alternative NDK locations can be specified by overriding the ANDROID_NDK_HOME, like so:

zap org.swift.swiftpm/swift-sdks % ANDROID_NDK_HOME="/opt/homebrew/share/android-ndk" swift-6.2-DEVELOPMENT-SNAPSHOT-2025-05-07-a-android-0.1.artifactbundle/swift-android/scripts/setup-android-sdk.sh
setup-android-sdk.sh: success: ndk-sysroot linked to Android SDK

zap org.swift.swiftpm/swift-sdks % tree swift-6.2-DEVELOPMENT-SNAPSHOT-2025-05-07-a-android-0.1.artifactbundle/swift-android/ndk-sysroot
└── usr
    ├── include -> /opt/homebrew/share/android-ndk/toolchains/llvm/prebuilt/darwin-x86_64/sysroot/usr/include
    └── lib
        ├── aarch64-linux-android -> /opt/homebrew/share/android-ndk/toolchains/llvm/prebuilt/darwin-x86_64/sysroot/usr/lib/aarch64-linux-android
        ├── arm-linux-androideabi -> /opt/homebrew/share/android-ndk/toolchains/llvm/prebuilt/darwin-x86_64/sysroot/usr/lib/arm-linux-androideabi
        ├── x86_64-linux-android -> /opt/homebrew/share/android-ndk/toolchains/llvm/prebuilt/darwin-x86_64/sysroot/usr/lib/x86_64-linux-android
        ├── swift
        │   └── android
        │       ├── aarch64
        │       │   └── swiftrt.o -> ../../../../../../swift-resources/usr/lib/swift-aarch64/android/aarch64/swiftrt.o
        │       ├── armv7
        │       │   └── swiftrt.o -> ../../../../../../swift-resources/usr/lib/swift-armv7/android/armv7/swiftrt.o
        │       └── x86_64
        │           └── swiftrt.o -> ../../../../../../swift-resources/usr/lib/swift-x86_64/android/x86_64/swiftrt.o
        └── swift_static
            └── android
                ├── aarch64
                │   └── swiftrt.o -> ../../../../../../swift-resources/usr/lib/swift_static-aarch64/android/aarch64/swiftrt.o
                ├── armv7
                │   └── swiftrt.o -> ../../../../../../swift-resources/usr/lib/swift_static-armv7/android/armv7/swiftrt.o
                └── x86_64
                    └── swiftrt.o -> ../../../../../../swift-resources/usr/lib/swift_static-x86_64/android/x86_64/swiftrt.o

[marcprux]

As of 72964f5, the Android SDK is now being built in a Docker container.

[etcwilde]

Working through this. One thing to note, https://github.com/swiftlang/swift-docker/blob/main/ci_test.py --

swift-docker/ci_test.py

Lines 79 to 83 in c95bc0c

	cmd = [
	'docker', 'build', '--no-cache=true',
	'-f', dockerfile,
	'-t', image_name,
	docker_dir

runs the docker build commands from the repository root, not from the subdirectory so scripts will need to be able to accommodate a working directory that is different from the directory where the script lives.

[marcprux]

I think it should be fine in theory to run the Dockerfile from another folder, but it does require some mount points to be set up (see https://github.com/swift-android-sdk/swift-docker/blob/main/swift-ci/sdks/android/build-docker#L63).

I also notice that the static-linux Dockerfile doesn't build out-of-the-box with a generic command like:

$ docker build --no-cache=true -f swift-ci/sdks/static-linux/Dockerfile .

…
--------------------
  86 |     RUN chmod ugo+x /scripts/*
  87 |     
  88 | >>> COPY resources /resources
  89 |     
  90 |     # Create a user
--------------------
ERROR: failed to build: failed to solve: failed to compute cache key: failed to calculate checksum of ref 19bdc85c-49c5-4899-bc25-2a1cffd11dfe::e0kqjvdnitebn8odzbggham6d: "/resources": not found

Is there some different command I should run to test it?

[etcwilde]

Started going through this. I think my main concerns right now are around cloning repo's that we are already cloning with update-checkout and the patches that haven't been merged into the repos yet. Otherwise it's generally looking fine. I still need to look more closely at the build.sh though.

[etcwilde]

I'm concerned about running this on every PR against the swift-docker repository.
At the moment, testing on this repo takes a few minutes maximum, while I suspect that this will increase that it pretty substantially. It might be good to either limit running it to changes to the android subdirectory, or we should make this a dedicated job on Swift CI like the static Linux Musl SDK instead.
CC @shahmishal, @justice-adams-apple

[marcprux]

I'm concerned about running this on every PR against the swift-docker repository.

Yeah, actually, that android-build CI part was intended to be expunged before this PR would be merged. 😊

It is just there so we can exercise updates to the pull request.

[etcwilde]

Okay, that sounds good to me. Either Justice or I can probably use it as a template for setting up the Jenkins job if we have questions later, so useful to have in history.

[marcprux]

@etcwilde, did you ever manage to run this and get an Android SDK artifactbundle out of it? We're itching to start publishing 6.2 snapshots of the SDK so we can get more eyes on it and start integrating those snapshots into our Android CI workflow.

[marcprux]

@etcwilde I was hoping we could get some feedback on this PR so we can discuss it at the Android Workgroup meeting on Wednesday. Did you ever run the SDK build script? The sooner we can starting publishing snapshots, the sooner we will be able to iron out any last kinks before 6.2 is released.

[etcwilde]

Do we want to include an example of the command(s) for running the build locally?

[marcprux]

Added in swift-android-sdk#14

[etcwilde]

Alternatively, save the pushd/popd call and let CMake run the build for you.

run cmake --build ${build_dir}/$arch/curl -- -j ${parallel_jobs}

[marcprux]

Fixed in swift-android-sdk#14

[etcwilde]

run cmake --install ${build_dir}/${arch}/curl

[marcprux]

Fixed in swift-android-sdk#14

[etcwilde]

We're already passing -S and -B to CMake. We shouldn't need the pushd/popd.

[marcprux]

Fixed in swift-android-sdk#14

[etcwilde]

We should use this to generate the spdx SBOM for the SDK like the static SDK does here:

swift-docker/swift-ci/sdks/static-linux/scripts/build.sh

Lines 757 to 871 in 3bf68fb

	spdx_uuid=$(uuidgen)
	spdx_doc_uuid=$(uuidgen)
	spdx_timestamp=$(date -Iseconds)
	sdk_name=swift-${swift_version}_static-linux-${static_linux_sdk_version}
	bundle="${sdk_name}.artifactbundle"
	rm -rf "${build_dir}/$bundle"
	mkdir -p "${build_dir}/$bundle/$sdk_name/swift-linux-musl"
	quiet_pushd ${build_dir}/$bundle
	# First the info.json, for SwiftPM
	cat > info.json <<EOF
	{
	"schemaVersion": "1.0",
	"artifacts": {
	"$sdk_name": {
	"variants": [
	{
	"path": "$sdk_name/swift-linux-musl"
	}
	],
	"version": "0.0.1",
	"type": "swiftSDK"
	}
	}
	}
	EOF
	# Now generate SPDX data
	cat > sbom.spdx.json <<EOF
	{
	"SPDXID": "SPDXRef-DOCUMENT",
	"name": "SBOM-SPDX-${spdx_uuid}",
	"spdxVersion": "SPDX-2.3",
	"creationInfo": {
	"created": "${spdx_timestamp}",
	"creators": [
	"Organization: Apple, Inc."
	]
	},
	"dataLicense": "Apache-2.0",
	"documentNamespace": "urn:uuid:${spdx_doc_uuid}",
	"documentDescribes": [
	"SPDXRef-Package-static-linux-sdk"
	],
	"packages": [
	EOF
	first=true
	for package in ${packages[@]}; do
	if [[ "$first" == "true" ]]; then
	first=false
	else
	cat >> sbom.spdx.json <<EOF
	},
	EOF
	fi
	snake=${package}_snake; snake=${!snake}
	version=${package}_version; version=${!version}
	name=${package}_name; name=${!name}
	license=${package}_license; license=${!license}
	url=${package}_url; url=${!url}
	cat >> sbom.spdx.json <<EOF
	{
	"SPDXID": "SPDXRef-Package-${snake}",
	"name": "${name}",
	"versionInfo": "${version}",
	"filesAnalyzed": false,
	"licenseDeclared": "${license}",
	"licenseConcluded": "${license}",
	"downloadLocation": "${url}",
	"copyrightText": "NOASSERTION",
	"checksums": []
	EOF
	done
	cat >> sbom.spdx.json <<EOF
	}
	],
	"relationships": [
	EOF
	first=true
	for package in ${packages[@]}; do
	if [[ "$package" == "static_linux_sdk" ]]; then
	continue
	fi
	if [[ "$first" == "true" ]]; then
	first=false
	else
	cat >> sbom.spdx.json <<EOF
	},
	EOF
	fi
	snake=${package}_snake; snake=${!snake}
	cat >> sbom.spdx.json <<EOF
	{
	"spdxElementId": "SPDXRef-Package-static-linux-sdk",
	"relationshipType": "GENERATED_FROM",
	"relatedSpdxElement": "SPDXRef-Package-${snake}"
	EOF
	done
	cat >> sbom.spdx.json <<EOF
	}
	]
	}
	EOF

[marcprux]

OK, I've added generation of a sbom.spdx.json file in swift-android-sdk#14, which will look like:

{
  "SPDXID": "SPDXRef-DOCUMENT",
  "name": "SBOM-SPDX-9fe120c9-d845-4586-876b-4080c9143143",
  "spdxVersion": "SPDX-2.3",
  "creationInfo": {
    "created": "2025-08-22T02:37:12+00:00",
    "creators": [
      "Organization: Apple, Inc."
    ]
  },
  "dataLicense": "Apache-2.0",
  "documentNamespace": "urn:uuid:cceb1cb9-34b6-4595-9e1f-9091c408d88b",
  "documentDescribes": [
    "SPDXRef-Package-swift-android-sdk"
  ],
  "packages": [
    {
      "SPDXID": "SPDXRef-Package-swift-android-sdk",
      "name": "Swift SDK for Android",
      "versionInfo": "",
      "filesAnalyzed": false,
      "licenseDeclared": "Apache-2.0",
      "licenseConcluded": "Apache-2.0",
      "downloadLocation": "https://swift.org/install",
      "copyrightText": "NOASSERTION",
      "checksums": []
    },
    {
      "SPDXID": "SPDXRef-Package-swift",
      "name": "swift",
      "versionInfo": "6.2-DEVELOPMENT-SNAPSHOT-2025-08-20-a",
      "filesAnalyzed": false,
      "licenseDeclared": "Apache-2.0",
      "licenseConcluded": "Apache-2.0",
      "downloadLocation": "https://swift.org",
      "copyrightText": "NOASSERTION",
      "checksums": []
    },
    {
      "SPDXID": "SPDXRef-Package-libxml2",
      "name": "libxml2",
      "versionInfo": "2.11.5",
      "filesAnalyzed": false,
      "licenseDeclared": "MIT",
      "licenseConcluded": "MIT",
      "downloadLocation": "https://github.com/GNOME/libxml2",
      "copyrightText": "NOASSERTION",
      "checksums": []
    },
    {
      "SPDXID": "SPDXRef-Package-curl",
      "name": "curl",
      "versionInfo": "8.9.1",
      "filesAnalyzed": false,
      "licenseDeclared": "MIT",
      "licenseConcluded": "MIT",
      "downloadLocation": "https://curl.se",
      "copyrightText": "NOASSERTION",
      "checksums": []
    },
    {
      "SPDXID": "SPDXRef-Package-boringssl",
      "name": "boringssl",
      "versionInfo": "fips-20220613",
      "filesAnalyzed": false,
      "licenseDeclared": "OpenSSL AND ISC AND MIT",
      "licenseConcluded": "OpenSSL AND ISC AND MIT",
      "downloadLocation": "https://boringssl.googlesource.com/boringssl/",
      "copyrightText": "NOASSERTION",
      "checksums": []
    }
  ],
  "relationships": [
    {
      "spdxElementId": "SPDXRef-Package-swift-android-sdk",
      "relationshipType": "GENERATED_FROM",
      "relatedSpdxElement": "SPDXRef-Package-swift"
    },
    {
      "spdxElementId": "SPDXRef-Package-swift-android-sdk",
      "relationshipType": "GENERATED_FROM",
      "relatedSpdxElement": "SPDXRef-Package-libxml2"
    },
    {
      "spdxElementId": "SPDXRef-Package-swift-android-sdk",
      "relationshipType": "GENERATED_FROM",
      "relatedSpdxElement": "SPDXRef-Package-curl"
    },
    {
      "spdxElementId": "SPDXRef-Package-swift-android-sdk",
      "relationshipType": "GENERATED_FROM",
      "relatedSpdxElement": "SPDXRef-Package-boringssl"
    }
  ]
}

[etcwilde]

Noticed an issue in one of the shebangs.
Do we want a /usr/bin/env bash? I know these scripts are documented to work on Ubuntu 24.04 so the /bin/bash should be fine, but it looks like most of the pieces should work on other linux distros too.