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Merged
ehsanghaffar merged 11 commits into from
Jul 28, 2026
Merged

fix: make syslinux download resilient (try multiple locations) #2

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2e296ca
fix: make syslinux download resilient (try multiple locations)
ehsanghaffar Nov 20, 2025
9b615e4
Refactor script directory variable assignments
ehsanghaffar Nov 20, 2025
694a79f
fix: make BusyBox build non-interactive and remove invalid BUILD_JOBS…
ehsanghaffar Nov 20, 2025
cc21f9b
fix: fallback to make defconfig if olddefconfig target is missing in …
ehsanghaffar Nov 20, 2025
096c3c8
Update BusyBox build process in Dockerfile
ehsanghaffar Nov 20, 2025
d664155
Update Syslinux version and improve build scripts
ehsanghaffar Nov 20, 2025
557c9c5
Refactor Dockerfile for better readability and formatting
ehsanghaffar Nov 20, 2025
9bb3ec6
Set bash as the shell with pipefail option in Dockerfile
ehsanghaffar Nov 20, 2025
4159439
fix dockerfile syntax
ehsanghaffar Nov 20, 2025
dd7cb59
Improve busybox build and installation process
ehsanghaffar Nov 20, 2025
b2ccec9
Refactor Dockerfile for robust build and artifact creation
ehsanghaffar Nov 20, 2025
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210 changes: 109 additions & 101 deletions Dockerfile
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Original file line number Diff line number Diff line change
Expand Up @@ -2,186 +2,204 @@
# =============================================================================
# Multi-stage Dockerfile for Building Custom Linux Distribution
# =============================================================================
# This Dockerfile builds a minimal Linux distribution from scratch using:
# - Linux Kernel (from torvalds/linux)
# - BusyBox (minimal userspace utilities)
# - Syslinux (bootloader)
# =============================================================================

# -----------------------------------------------------------------------------
# Stage 1: Base builder with build dependencies
# -----------------------------------------------------------------------------
FROM debian:sid-slim AS builder-base

# Set build arguments for versioning and configuration
ARG LINUX_VERSION=master
ARG BUSYBOX_VERSION=master
ARG SYSLINUX_VERSION=6.04-pre1
ARG SYSLINUX_VERSION=6.03
ARG DEBIAN_FRONTEND=noninteractive
ARG BUILD_JOBS=auto
ARG BUILD_JOBS=

# Add metadata labels
LABEL maintainer="handbuilt-linux-project"
LABEL description="Custom Linux distribution builder"
LABEL version="1.0.0"

# Install build dependencies in a single layer with cleanup
# hadolint ignore=DL3008
# Install build dependencies
RUN --mount=type=cache,target=/var/cache/apt,sharing=locked \
--mount=type=cache,target=/var/lib/apt,sharing=locked \
apt-get update && \
apt-get install -yq --no-install-recommends \
build-essential \
bzip2 \
git \
make \
gcc \
libncurses-dev \
flex \
bison \
bc \
cpio \
libelf-dev \
libssl-dev \
syslinux-common \
dosfstools \
genisoimage \
wget \
curl \
ca-certificates \
xz-utils && \
build-essential \
bzip2 \
git \
make \
gcc \
libncurses-dev \
flex \
bison \
bc \
cpio \
libelf-dev \
libssl-dev \
syslinux-common \
dosfstools \
genisoimage \
wget \
curl \
ca-certificates \
xz-utils && \
apt-get clean && \
rm -rf /var/lib/apt/lists/*

# Set working directory
WORKDIR /build

# -----------------------------------------------------------------------------
# Stage 2: Download and prepare sources
# Stage: source-downloader
# -----------------------------------------------------------------------------
FROM builder-base AS source-downloader

ARG LINUX_VERSION=master
ARG BUSYBOX_VERSION=master
ARG SYSLINUX_VERSION=6.03

# Create directory structure
RUN mkdir -p /build/initramfs && \
mkdir -p /build/myiso/isolinux && \
mkdir -p /build/sources
mkdir -p /build/sources && \
mkdir -p /build/cache

# Download Linux kernel source
WORKDIR /build/sources

# Clone Linux (shallow, branch/tag from ARG)
RUN --mount=type=cache,target=/build/cache \
if [ ! -f /build/cache/linux/.git/config ]; then \
git clone --depth 1 \
https://github.com/torvalds/linux.git linux && \
cp -r linux /build/cache/linux; \
if [ ! -d /build/cache/linux ]; then \
git clone --depth 1 --branch "${LINUX_VERSION}" https://github.com/torvalds/linux.git linux || \
git clone --depth 1 https://github.com/torvalds/linux.git linux; \
cp -r linux /build/cache/linux; \
else \
cp -r /build/cache/linux linux; \
cp -r /build/cache/linux linux; \
fi

# Download BusyBox source
# Clone BusyBox (shallow, branch/tag from ARG)
WORKDIR /build/sources
RUN --mount=type=cache,target=/build/cache \
if [ ! -f /build/cache/busybox/.git/config ]; then \
git clone --depth 1 \
https://git.busybox.net/busybox busybox && \
cp -r busybox /build/cache/busybox; \
if [ ! -d /build/cache/busybox ]; then \
git clone --depth 1 --branch "${BUSYBOX_VERSION}" https://git.busybox.net/busybox busybox || \
git clone --depth 1 https://git.busybox.net/busybox busybox; \
cp -r busybox /build/cache/busybox; \
else \
cp -r /build/cache/busybox busybox; \
cp -r /build/cache/busybox busybox; \
fi

# Download and extract Syslinux
# Note: Using alternative download locations due to mirror availability
# Download and extract Syslinux (tries multiple URLs)
WORKDIR /build/sources
RUN curl -fsSL -o syslinux.tar.gz \
"https://www.kernel.org/pub/linux/utils/boot/syslinux/syslinux-6.03.tar.gz" || \
curl -fsSL -o syslinux.tar.gz \
"https://mirrors.edge.kernel.org/pub/linux/utils/boot/syslinux/syslinux-6.03.tar.gz" && \
tar xzf syslinux.tar.gz && \
rm syslinux.tar.gz && \
mv syslinux-* syslinux
RUN set -eux; \
tried=0; \
for url in \
"https://mirrors.edge.kernel.org/pub/linux/utils/boot/syslinux/syslinux-${SYSLINUX_VERSION}.tar.gz" \
"https://www.kernel.org/pub/linux/utils/boot/syslinux/syslinux-${SYSLINUX_VERSION}.tar.gz" \
"https://mirrors.edge.kernel.org/pub/linux/utils/boot/syslinux/Testing/${SYSLINUX_VERSION}/syslinux-${SYSLINUX_VERSION}.tar.gz"; do \
echo "Trying $url"; \
if curl -fsSL -o syslinux.tar.gz "$url"; then \
tried=1; \
break; \
else \
echo "Failed to download from $url"; \
fi; \
done; \
if [ "$tried" -ne 1 ]; then \
echo "ERROR: Unable to download syslinux ${SYSLINUX_VERSION}" >&2; \
exit 22; \
fi; \
tar xzf syslinux.tar.gz && rm syslinux.tar.gz && mv "syslinux-${SYSLINUX_VERSION}" syslinux

# -----------------------------------------------------------------------------
# Stage 3: Build Linux kernel
# Stage: kernel-builder
# -----------------------------------------------------------------------------
FROM builder-base AS kernel-builder

ARG BUILD_JOBS
ARG LINUX_VERSION=master

# Copy kernel source from downloader stage
COPY --from=source-downloader /build/sources/linux /build/linux

# Copy kernel configuration
# If you have a linux.config in repo, it will be copied by the build context
COPY linux.config /build/linux/.config

# Build kernel
WORKDIR /build/linux
RUN make olddefconfig && \
make -j"${BUILD_JOBS:-$(nproc)}" && \
(strip --strip-debug arch/x86/boot/bzImage 2>/dev/null || true)

# -----------------------------------------------------------------------------
# Stage 4: Build BusyBox
# Stage: busybox-builder
# -----------------------------------------------------------------------------
FROM builder-base AS busybox-builder

ARG BUILD_JOBS
ARG BUSYBOX_VERSION=master

# Copy BusyBox source from downloader stage
COPY --from=source-downloader /build/sources/busybox /build/busybox

# Copy BusyBox configuration
COPY busybox.config /build/busybox/.config

# Build and install BusyBox
WORKDIR /build/busybox
RUN make oldconfig && \
make -j"${BUILD_JOBS:-$(nproc)}" && \
make CONFIG_PREFIX=/build/initramfs install && \
strip /build/initramfs/bin/busybox

# Use a robust config, build, install; create an explicit tarball artifact and verify it
SHELL ["/bin/bash", "-o", "pipefail", "-c"]
RUN set -eux; \
mkdir -p /build/initramfs; \
# configure (prefer existing .config, accept defaults non-interactively)
if [ -f .config ]; then \
if ! yes "" | make oldconfig; then \
make defconfig; \
fi; \
else \
make defconfig; \
fi; \
# build
make -j"${BUILD_JOBS:-$(nproc)}"; \
# install into explicit path
make CONFIG_PREFIX=/build/initramfs install; \
# sanity checks — fail early with diagnostics if artifacts missing
if [ ! -x /build/initramfs/bin/busybox ]; then \
echo "ERROR: busybox install did not produce /build/initramfs/bin/busybox"; \
echo "workspace /build contents:"; ls -la /build || true; \
echo "busybox tree:"; ls -la /build/initramfs || true; \
exit 1; \
fi; \
# shrink binary if possible (non-fatal)
strip --strip-all /build/initramfs/bin/busybox || true; \
# create a single tarball artifact for reliable COPY by BuildKit
tar -C /build -czf /build/initramfs.tar.gz initramfs; \
ls -la /build/initramfs.tar.gz

# -----------------------------------------------------------------------------
# Stage 5: Create initramfs
# Stage: initramfs-builder
# -----------------------------------------------------------------------------
FROM builder-base AS initramfs-builder

# Copy BusyBox installation
COPY --from=busybox-builder /build/initramfs /build/initramfs
# Copy the tarball artifact and extract it, then add/overwrite init
COPY --from=busybox-builder /build/initramfs.tar.gz /build/initramfs.tar.gz

WORKDIR /build
RUN set -eux; \
mkdir -p /build; \
tar -C /build -xzf /build/initramfs.tar.gz && rm /build/initramfs.tar.gz; \
ls -la /build/initramfs

# Copy init script and make it executable
COPY init.sh /build/initramfs/init
RUN chmod +x /build/initramfs/init

# Create initramfs archive
WORKDIR /build/initramfs
SHELL ["/bin/bash", "-o", "pipefail", "-c"]
RUN find . -print0 | cpio --null --create --format=newc | gzip -9 > /build/initramfs.cpio.gz

# -----------------------------------------------------------------------------
# Stage 6: Create bootable ISO
# Stage: iso-builder
# -----------------------------------------------------------------------------
FROM builder-base AS iso-builder

# Copy syslinux files
COPY --from=source-downloader /build/sources/syslinux /build/syslinux
ARG SYSLINUX_VERSION=6.03

# Copy kernel
COPY --from=source-downloader /build/sources/syslinux /build/syslinux
COPY --from=kernel-builder /build/linux/arch/x86/boot/bzImage /build/myiso/bzImage

# Copy initramfs
COPY --from=initramfs-builder /build/initramfs.cpio.gz /build/myiso/initramfs

# Copy syslinux bootloader files
WORKDIR /build
RUN cp /build/syslinux/bios/core/isolinux.bin /build/myiso/isolinux/ && \
cp /build/syslinux/bios/com32/elflink/ldlinux/ldlinux.c32 /build/myiso/isolinux/

# Copy bootloader configuration
COPY syslinux.cfg /build/myiso/isolinux/isolinux.cfg

# Create bootable ISO
WORKDIR /build
RUN mkisofs \
-J \
Expand All @@ -195,56 +213,46 @@ RUN mkisofs \
myiso

# -----------------------------------------------------------------------------
# Stage 7: Final minimal image with artifacts
# Stage: export-stage
# -----------------------------------------------------------------------------
FROM scratch AS export-stage

# Copy build artifacts
COPY --from=iso-builder /build/output.iso /output.iso
COPY --from=kernel-builder /build/linux/arch/x86/boot/bzImage /bzImage
COPY --from=initramfs-builder /build/initramfs.cpio.gz /initramfs

# -----------------------------------------------------------------------------
# Stage 8: Runtime image (default)
# Stage: runtime
# -----------------------------------------------------------------------------
FROM debian:sid-slim AS runtime

# Install only runtime dependencies
RUN --mount=type=cache,target=/var/cache/apt,sharing=locked \
--mount=type=cache,target=/var/lib/apt,sharing=locked \
apt-get update && \
apt-get install -yq --no-install-recommends \
qemu-system-x86 \
qemu-utils && \
qemu-system-x86 \
qemu-utils && \
apt-get clean && \
rm -rf /var/lib/apt/lists/*

# Create non-root user for better security
RUN groupadd -r distro && \
useradd -r -g distro -d /distro -s /bin/bash distro && \
mkdir -p /distro && \
chown -R distro:distro /distro

# Copy build artifacts from iso-builder stage
COPY --from=iso-builder /build/output.iso /distro/output.iso
COPY --from=kernel-builder /build/linux/arch/x86/boot/bzImage /distro/bzImage
COPY --from=initramfs-builder /build/initramfs.cpio.gz /distro/initramfs

# Copy scripts
COPY --chown=distro:distro build.sh /distro/build.sh
RUN chmod +x /distro/build.sh

# Set working directory and user
WORKDIR /distro
USER distro

# Set environment variables
ENV DISTRO_HOME=/distro
ENV PATH="${DISTRO_HOME}:${PATH}"

# Health check
HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
CMD [ -f "/distro/output.iso" ] || exit 1

# Default command
CMD ["/bin/bash"]
CMD ["/bin/bash"]
6 changes: 4 additions & 2 deletions scripts/clean.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -6,8 +6,10 @@

set -euo pipefail

readonly SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
readonly PROJECT_DIR="$(dirname "${SCRIPT_DIR}")"
readonly SCRIPT_DIR
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
readonly PROJECT_DIR
PROJECT_DIR="$(dirname "${SCRIPT_DIR}")"

readonly GREEN='\033[0;32m'
readonly BLUE='\033[0;34m'
Expand Down
6 changes: 4 additions & 2 deletions scripts/test.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -6,8 +6,10 @@

set -euo pipefail

readonly SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
readonly PROJECT_DIR="$(dirname "${SCRIPT_DIR}")"
readonly SCRIPT_DIR
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
Comment on lines +9 to +10

@chatgpt-codex-connector chatgpt-codex-connector Bot Jul 28, 2026

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P2 Badge Assign variables before marking them readonly

With Bash, readonly SCRIPT_DIR marks the name immutable immediately, so the following assignment aborts with SCRIPT_DIR: readonly variable; as a result ./scripts/test.sh exits before running any tests (the same split declaration pattern also breaks scripts/clean.sh). Keep the assignment in the readonly declaration or assign first and mark it readonly afterward.

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readonly PROJECT_DIR
PROJECT_DIR="$(dirname "${SCRIPT_DIR}")"

readonly GREEN='\033[0;32m'
readonly RED='\033[0;31m'
Expand Down
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