mirror of
https://github.com/kata-containers/kata-containers.git
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9b816aa0ac
Add a self-contained "devkit" guest extension: a minimal Alpine (musl + busybox + apk) rootfs with common debug tools prebaked (strace, ltrace, iproute2, procps, lsof, tcpdump, pciutils, util-linux, ...), built as a measured erofs+dm-verity image mounted at /run/kata-extensions/devkit. The production guest rootfs is minimal (and, for some bases, shell-less), so the agent debug console has no rich interactive shell. Rather than rebuilding the whole rootfs with debug tooling, this optional extension can be cold-plugged alongside any base image. At runtime the guest helper scripts overlay a writable tmpfs on the read-only extension and chroot in, so apk and every tool run natively against a normal root filesystem; `devkit-apk add <pkg>` (or plain `apk add` inside the debug shell) installs anything else into the overlay. Alpine's own busybox-static (/bin/busybox.static) bootstraps the overlay/chroot from the shell-less base (the dynamic musl loader is not present there yet); it is installed at a dedicated path so it never clobbers Alpine's /bin/busybox or /bin/sh, which are needed unclobbered inside the chroot. The image is assembled directly and handed to image_builder.sh (mirroring the CoCo extension), never going through rootfs.sh: it ships no kata-agent, kernel or driver userspace. No runtime wiring is added here; that follows in later commits. Nothing consumes the image yet. Signed-off-by: Fabiano Fidêncio <ffidencio@nvidia.com> Assisted-by: Cursor <cursoragent@cursor.com>
32 lines
1.1 KiB
Bash
32 lines
1.1 KiB
Bash
#!/run/kata-extensions/devkit/bin/busybox.static sh
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# shellcheck shell=dash
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#
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# Copyright (c) Kata Containers Community
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#
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# SPDX-License-Identifier: Apache-2.0
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#
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# Interactive devkit debug shell: the debug_console_shell target, reached via
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# ${DEVKIT}/bin/devkit-sh -> this.
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#
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# NOTE: the bootstrap busybox ash has no builtin/PATH `[`, so use "${BB}" test.
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DEVKIT=/run/kata-extensions/devkit
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# BB and MERGED are exported by the sourced devkit-init, resolved at runtime.
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# shellcheck source=tools/osbuilder/rootfs-builder/devkit/devkit-init.sh
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. "${DEVKIT}/usr/bin/devkit-init"
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devkit_setup_chroot || {
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"${BB}" echo "devkit: failed to set up chroot environment" >&2
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exit 1
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}
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# Prefer the prebaked bash, falling back to busybox ash (/bin/sh) if bash is
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# missing or not executable in the merged tree.
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shell=/bin/bash
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"${BB}" test -x "${MERGED}${shell}" || shell=/bin/sh
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# The agent execs the shell with no arguments, so default to a login shell; any
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# arguments (-i, -c "cmd", ...) pass straight through.
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"${BB}" test "$#" -eq 0 && set -- -l
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exec "${BB}" chroot "${MERGED}" "${shell}" "$@"
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