Create multiarch image by cross-compiling Swift package to arm64

.github/workflows/deploy.yml

@@ -11,6 +11,7 @@ on:
 jobs:
   deploy:
     runs-on: ubuntu-latest
+    if: github.ref == 'refs/heads/main'
     steps:
     - uses: actions/checkout@v3
     - name: Set up Kubernetes CLI

.github/workflows/docker.yml

@@ -4,6 +4,7 @@ on:
   push:
     branches:
     - main
+  pull_request:
   workflow_dispatch:
 
 jobs:
@@ -25,11 +26,7 @@ jobs:
       uses: docker/build-push-action@v4
       with:
         context: .
-        # TODO: Ideally we could just build an aarch64 image too (under QEMU user-mode emulation) by using
-        #
-        #       platforms: linux/amd64,linux/arm64/v8
-        #
-        # See https://github.com/fwcd/d2/issues/124
-        platforms: linux/amd64
-        push: true
+        platforms: linux/amd64,linux/arm64/v8
+        push: true # TODO: Only push on main
         tags: ghcr.io/fwcd/d2:latest
+

Dockerfile

@@ -1,17 +1,46 @@
-FROM swift:5.7 as builder
+ARG SWIFTVERSION=5.8.1
+ARG UBUNTUDISTRO=jammy
 
-# Install native dependencies
+FROM swift:${SWIFTVERSION}-${UBUNTUDISTRO} AS sysroot
+
+WORKDIR /opt/d2
+
+# Install build dependencies into target sysroot
 COPY Scripts/install-build-dependencies-apt Scripts/
 RUN Scripts/install-build-dependencies-apt && rm -rf /var/lib/apt/lists/*
 
-# Build
+FROM --platform=$BUILDPLATFORM swift:${SWIFTVERSION}-${UBUNTUDISTRO} AS builder
+
+ARG SWIFTVERSION
+ARG UBUNTUDISTRO
+ARG BUILDARCH
+ARG TARGETARCH
+
+ARG TARGETSYSROOT=/usr/local/${TARGETARCH}-ubuntu-${UBUNTUDISTRO}
+
 WORKDIR /opt/d2
+
+# Copy target sysroot into builder
+# TODO: Only copy stuff that we need for compilation (/usr/lib, /usr/include etc.)
+COPY --from=sysroot / ${TARGETSYSROOT}
+
+# Install (cross-)GCC and patch some paths
+COPY Scripts/prepare-docker-buildroot Scripts/get-linux-arch-name Scripts/
+RUN Scripts/prepare-docker-buildroot
+
+# (Cross-)compile D2
 COPY Sources Sources
 COPY Tests Tests
 COPY Package.swift Package.resolved ./
-RUN swift build -c release
+COPY Scripts/build-release Scripts/
+RUN Scripts/build-release
+
+FROM swift:${SWIFTVERSION}-${UBUNTUDISTRO}-slim AS runner
 
-FROM swift:5.7-slim as runner
+ARG TARGETARCH
+ARG UBUNTUDISTRO
+
+ARG TARGETSYSROOT=/usr/local/${TARGETARCH}-ubuntu-${UBUNTUDISTRO}
 
 # Install Curl, add-apt-repository and node package repository
 RUN apt-get update && apt-get install -y curl software-properties-common && rm -rf /var/lib/apt/lists/*
@@ -21,6 +50,10 @@ RUN curl -sL https://deb.nodesource.com/setup_18.x | bash -
 COPY Scripts/install-runtime-dependencies-apt Scripts/
 RUN Scripts/install-runtime-dependencies-apt && rm -rf /var/lib/apt/lists/*
 
+# Link 'sysroot' to / to make sure D2 can find the Swift stdlibs
+# (the runpath within the D2 executable still points to its /usr/lib/swift)
+RUN ln -s / ${TARGETSYSROOT}
+
 WORKDIR /opt/d2
 
 # Install Node dependencies
@@ -32,9 +65,13 @@ RUN Scripts/install-node-dependencies
 COPY Resources Resources
 COPY LICENSE README.md ./
 
+ARG TARGETOS
+ARG TARGETARCH
+
 # Set up .build folder in runner
 WORKDIR /opt/d2/.build
-RUN mkdir -p x86_64-unknown-linux-gnu/release && ln -s x86_64-unknown-linux-gnu/release release
+COPY Scripts/setup-dotbuild-tree Scripts/
+RUN Scripts/setup-dotbuild-tree
 
 # Copy font used by swiftplot to the correct path
 COPY --from=builder \

Scripts/build-release

@@ -0,0 +1,30 @@
+#!/bin/bash
+
+# (Cross-)compile D2
+
+set -e
+cd "$(dirname $0)/.."
+
+extra_flags=()
+
+if [ -n "$TARGETARCH" ] && [ -n "$TARGETSYSROOT" ]; then
+  echo "==> Setting flags for target arch '$TARGETARCH'"
+  arch_name="$(Scripts/get-linux-arch-name $TARGETARCH)"
+
+  extra_flags+=(
+    --arch "$arch_name"
+    --sdk "$TARGETSYSROOT"
+    -Xswiftc -use-ld=lld
+    -Xswiftc -resource-dir -Xswiftc "$TARGETSYSROOT/usr/lib/swift"
+    -Xswiftc -tools-directory -Xswiftc "/usr/$arch_name-linux-gnu/bin"
+    -Xcc -I"$TARGETSYSROOT/usr/include"
+    -Xcc -I"$TARGETSYSROOT/usr/include/freetype2"
+    -Xcc -I"$TARGETSYSROOT/usr/include/$arch_name-linux-gnu"
+    -Xcc -I"$TARGETSYSROOT/usr/include/cairo"
+    -Xlinker -L"$TARGETSYSROOT/usr/lib"
+    -Xlinker -L"$TARGETSYSROOT/usr/lib/$arch_name-linux-gnu" # libtesseract installs there
+  )
+fi
+
+echo "==> Building D2 with flags ${extra_flags[@]}"
+exec swift build -c release "${extra_flags[@]}"

Scripts/get-linux-arch-name

@@ -0,0 +1,18 @@
+#!/bin/bash
+
+# Unfortunately, Docker uses a different name for some CPU architectures than some
+# Linux tools (arm64 vs aarch64, amd64 vs x86_64, ...), therefore we use this script
+# to perform this mapping once and for all.
+
+set -e
+
+if [ $# -lt 1 ]; then
+  echo "Usage: $0 [arch name]"
+  exit 1
+fi
+
+case "$1" in
+  amd64) echo "x86_64";;
+  arm64) echo "aarch64";;
+  *)     echo "$1";;
+esac

Scripts/install-build-dependencies-apt

@@ -5,12 +5,25 @@
 set -e
 cd "$(dirname $0)/.."
 
-apt-get update
-apt-get install -y \
-  libcairo2-dev \
-  libsqlite3-dev \
-  libleptonica-dev \
-  libtesseract-dev \
+dependencies=(
+  libcairo2-dev
+  libsqlite3-dev
+  libleptonica-dev
+  libtesseract-dev
   libgraphviz-dev
+  libstdc++-12-dev
+  # TODO: poppler-utils and libssl1.1 needed?
+)
+
+echo "==> Installing add-apt-repository"
+apt-get update
+apt-get install -y software-properties-common
 
-# TODO: poppler-utils and libssl1.1 needed?
+echo "==> Enabling all repositories"
+for repo in main universe multiverse; do
+  add-apt-repository $repo
+done
+
+echo "==> Installing ${dependencies[@]}"
+apt-get update
+apt-get install -y "${dependencies[@]}"

Scripts/install-runtime-dependencies-apt

@@ -5,12 +5,14 @@
 set -e
 cd "$(dirname $0)/.."
 
-apt-get update
-apt-get install -y \
-  libcairo2 \
-  libsqlite3-0 \
-  tesseract-ocr \
-  graphviz \
+dependencies=(
+  libcairo2
+  libsqlite3-0
+  tesseract-ocr
+  graphviz
   nodejs
+  # TODO: poppler-utils and libssl1.1 needed?
+)
 
-# TODO: poppler-utils and libssl1.1 needed?
+apt-get update
+apt-get install -y "${dependencies[@]}"

Scripts/prepare-docker-buildroot

@@ -0,0 +1,63 @@
+#!/bin/bash
+
+# Prepares the build stage during the Docker image build. This assumes
+# that the target sysroot has already been installed to $TARGETSYSROOT.
+
+set -e
+cd "$(dirname $0)/.."
+
+if [ -z "$BUILDARCH" ]; then
+  echo "Please make sure to specify BUILDARCH!"
+  exit 1
+fi
+
+if [ -z "$TARGETARCH" ]; then
+  echo "Please make sure to specify TARGETARCH!"
+  exit 1
+fi
+
+if [ -z "$TARGETSYSROOT" ]; then
+  echo "Please make sure to specify TARGETSYSROOT!"
+  exit 1
+fi
+
+arch_name="$(Scripts/get-linux-arch-name $TARGETARCH)"
+
+echo "==> Updating apt..."
+apt-get update
+
+if [ "$BUILDARCH" == "$TARGETARCH" ]; then
+  echo "==> Installing build essentials"
+  apt-get install -y build-essential
+else
+  # Apparently, we need to symlink libstdc++ manually
+  if [ ! -f "$TARGETSYSROOT/usr/lib/$arch_name-linux-gnu/libstdc++.so" ]; then
+    echo "==> Symlinking libstdc++"
+    ln -s "$TARGETSYSROOT/usr/lib/$arch_name-linux-gnu/libstdc++.so"{.6,}
+  fi
+
+  # Symlinking the sysroot libs into the cross-GCC libs
+  # fixes a very strange linking issue where the linker would
+  # try resolving libc in /lib/$arch_name-linux-gnu. This also
+  # needs to happen before installing the cross-GCC package.
+  echo "==> Symlinking sysroot libs into cross-GCC libs"
+  mkdir -p "/usr/$arch_name-linux-gnu"
+  ln -s "$TARGETSYSROOT/usr/lib/$arch_name-linux-gnu" "/usr/$arch_name-linux-gnu/lib"
+
+  echo "==> Installing cross-GCC"
+  apt-get install -y gcc-$arch_name-linux-gnu
+fi
+
+# Workaround for https://github.com/stephencelis/CSQLite/pull/1
+if [ ! -f /usr/include/sqlite3.h ]; then
+  echo "==> Patching sqlite3.h"
+  ln -s {"$TARGETSYSROOT",}/usr/include/sqlite3.h
+fi
+
+# There seem to be some strange errors with <tgmath.h> (glibc)
+# on host + target x86_64. Since this header seems to be provided
+# elsewhere, we can remove it from the target sysroot as a workaround.
+if [ "$BUILDARCH" = amd64 ] && [ "$TARGETARCH" = amd64 ] && [ -f "$TARGETSYSROOT/usr/include/tgmath.h" ]; then
+  echo "==> Patching tgmath.h"
+  mv "$TARGETSYSROOT/usr/include/tgmath.h"{,.backup}
+fi

Scripts/setup-dotbuild-tree

@@ -0,0 +1,41 @@
+#!/bin/bash
+
+set -e
+cd "$(dirname $0)/.."
+
+if [ -n "$TARGETOS" ]; then
+  case "$TARGETOS" in
+    linux)
+      vendor=unknown
+      os=linux-gnu
+      ;;
+    *)
+      echo "Unsupported target os '$TARGETOS'"
+      exit 1
+      ;;
+  esac
+else
+  echo "Please specify the target OS by setting the TARGETOS variable!"
+  exit 1
+fi
+
+if [ -n "$TARGETARCH" ]; then
+  case "$TARGETARCH" in
+    amd64) arch=x86_64;;
+    arm64) arch=arm64;;
+    *)
+      echo "Unsupported target arch '${D2TARGETARCH[@]}'"
+      exit 1
+      ;;
+  esac
+else
+  echo "Please specify the target arch by setting the TARGETARCH variable!"
+  exit 1
+fi
+
+config=release
+
+mkdir -p .build/"$arch-$vendor-$os"/"$config"
+
+cd .build
+ln -s "$config" "$arch-$vendor-$os"/"$config"