[PATCH v1 0/2] scripts: introduce containerized builds

[PATCH v1 0/2] scripts: introduce containerized builds

[Guillaume Tucker]

This proposal emerged from an email discussion and a talk at Plumbers
last year:

    https://lore.kernel.org/all/affb7aff-dc9b-4263-bbd4-a7965c19ac4e@gtucker.io/

The aim is to facilitate reproducing builds for CI bots as well as
developers using containers.  Here's an illustrative example with a
kernel.org toolchain in a Docker image from tuxmake:

    $ scripts/container -i tuxmake/korg-clang-21 make LLVM=1 defconfig
      HOSTCC  scripts/basic/fixdep
      HOSTCC  scripts/kconfig/conf.o
    [...]
      HOSTCC  scripts/kconfig/util.o
      HOSTLD  scripts/kconfig/conf
    *** Default configuration is based on 'x86_64_defconfig'
    #
    # configuration written to .config
    #

and a follow-up command to build the kernel with the verbose flag
turned on to show DEBUG log messages from the container tool:

    $ scripts/container -i tuxmake/korg-clang-21 -v -- make LLVM=1 -j8
    [container DEBUG] runtime=docker, image=tuxmake/korg-clang-21
      GEN     arch/x86/include/generated/asm/orc_hash.h
      HOSTCC  scripts/basic/fixdep
      SYSHDR  arch/x86/include/generated/uapi/asm/unistd_32.h
      SYSHDR  arch/x86/include/generated/uapi/asm/unistd_64.h
      SYSHDR  arch/x86/include/generated/uapi/asm/unistd_x32.h
      WRAP    arch/x86/include/generated/uapi/asm/bpf_perf_event.h
      WRAP    arch/x86/include/generated/uapi/asm/errno.h
    [...]
      LD      arch/x86/boot/setup.elf
      OBJCOPY arch/x86/boot/setup.bin
      BUILD   arch/x86/boot/bzImage
    Kernel: arch/x86/boot/bzImage is ready  (#1)

While the example above uses a tuxmake image, I've also started
preparing reference container images with kernel.org toolchains and
no third-party dependencies other than the base Debian distro:

    https://gitlab.com/gtucker/korg-containers

This patch series include a documentation page with all the relevant
details about how to use the tool and images currently available.

Guillaume Tucker (2):
  scripts: add tool to run containerized builds
  Documentation: dev-tools: add container.rst page

 Documentation/dev-tools/container.rst | 175 ++++++++++++++++++++++++++
 Documentation/dev-tools/index.rst     |   1 +
 scripts/container                     | 112 +++++++++++++++++
 3 files changed, 288 insertions(+)
 create mode 100644 Documentation/dev-tools/container.rst
 create mode 100755 scripts/container

-- 
2.47.3

[PATCH v1 1/2] scripts: add tool to run containerized builds

[Guillaume Tucker]

Add a 'scripts/container' tool written in Python to run any command in
the source tree from within a container.  This can typically be used
to call 'make' with a compiler toolchain image to run reproducible
builds but any arbitrary command can be run too.  Only Docker and
Podman are supported for this initial version.

Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Link: https://lore.kernel.org/all/affb7aff-dc9b-4263-bbd4-a7965c19ac4e@gtucker.io/
Signed-off-by: Guillaume Tucker <gtucker@gtucker.io>
---
 scripts/container | 112 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 112 insertions(+)
 create mode 100755 scripts/container

diff --git a/scripts/container b/scripts/container
new file mode 100755
index 000000000000..74644ac33685
--- /dev/null
+++ b/scripts/container
@@ -0,0 +1,112 @@
+#!/bin/env python3
+# SPDX-License-Identifier: GPL-2.0-only
+# Copyright (C) 2025 Guillaume Tucker
+
+"""Containerized builds"""
+
+import argparse
+import logging
+import os
+import subprocess
+import sys
+
+
+def get_logger(verbose):
+    """Set up a logger with the appropriate level"""
+    logger = logging.getLogger('container')
+    handler = logging.StreamHandler()
+    handler.setFormatter(logging.Formatter(
+        fmt='[container {levelname}] {message}', style='{'
+    ))
+    logger.addHandler(handler)
+    logger.setLevel(logging.DEBUG if verbose is True else logging.INFO)
+    return logger
+
+
+def run_docker(args):
+    """Run a command in a Docker container"""
+    uid = args.uid or os.getuid()
+    gid = args.gid or args.uid or os.getgid()
+    cmd = [
+        'docker', 'run',
+        '--interactive',
+        '--volume', f'{os.getcwd()}:/src',
+        '--workdir', '/src',
+        '--user', f'{uid}:{gid}'
+    ]
+    if args.env_file:
+        cmd += ['--env-file', args.env_file]
+    cmd.append(args.image)
+    cmd += args.cmd
+    return subprocess.call(cmd)
+
+
+def run_podman(args):
+    """Run a command in a Podman container"""
+    uid = args.uid or 1000
+    gid = args.gid or args.uid or 1000
+    cmd = [
+        'podman', 'run',
+        '--interactive',
+        '--volume', f'{os.getcwd()}:/src',
+        '--workdir', '/src',
+        '--userns', f'keep-id:uid={uid},gid={gid}',
+    ]
+    if args.env_file:
+        cmd += ['--env-file', args.env_file]
+    cmd.append(args.image)
+    cmd += args.cmd
+    return subprocess.call(cmd)
+
+
+def main(args):
+    """Main entry point for the container tool"""
+    logger = get_logger(args.verbose)
+    logger.debug("runtime=%s, image=%s", args.runtime, args.image)
+    runtimes = {
+        'docker': run_docker,
+        'podman': run_podman,
+    }
+    handler = runtimes.get(args.runtime)
+    if not handler:
+        logger.error("Unknown container runtime: %s", args.runtime)
+        return 1
+    try:
+        return handler(args)
+    except KeyboardInterrupt:
+        logger.error("aborted")
+        return 1
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser("Containerized builds")
+    parser.add_argument(
+        '-e', '--env-file',
+        help="Path to an environment file to load in the container."
+    )
+    parser.add_argument(
+        '-g', '--gid',
+        help="Group ID to use inside the container."
+    )
+    parser.add_argument(
+        '-i', '--image', default='gcc',
+        help="Container image, default is gcc."
+    )
+    parser.add_argument(
+        '-r', '--runtime', choices=['docker', 'podman'], default='docker',
+        help="Container runtime, default is docker."
+    )
+    parser.add_argument(
+        '-u', '--uid',
+        help="User ID to use inside the container.  If the -g option is not"
+        "specified, the user ID will also be used for the group ID."
+    )
+    parser.add_argument(
+        '-v', '--verbose', action='store_true',
+        help="Enable verbose output."
+    )
+    parser.add_argument(
+        'cmd', nargs='+',
+        help="Command to run in the container"
+    )
+    sys.exit(main(parser.parse_args(sys.argv[1:])))
-- 
2.47.3

Re: [PATCH v1 1/2] scripts: add tool to run containerized builds

[Guillaume Tucker]

[+Onur - sorry I didn't Cc you when sending this series]

On 10/12/2025 2:58 pm, Guillaume Tucker wrote:
> +def run_docker(args):
> +    """Run a command in a Docker container"""
> +    uid = args.uid or os.getuid()
> +    gid = args.gid or args.uid or os.getgid()
> +    cmd = [
> +        'docker', 'run',
> +        '--interactive',
> +        '--volume', f'{os.getcwd()}:/src',
> +        '--workdir', '/src',
> +        '--user', f'{uid}:{gid}'
> +    ]
> +    if args.env_file:
> +        cmd += ['--env-file', args.env_file]
> +    cmd.append(args.image)
> +    cmd += args.cmd
> +    return subprocess.call(cmd)

Just realised that it also needs a TTY to handle Ctrl-C signals
correctly, otherwise the Python process would stop but the container
would keep running in a detached process (same for podman):


diff --git a/scripts/container b/scripts/container
index 74644ac33685..e05425c06d28 100755
--- a/scripts/container
+++ b/scripts/container
@@ -30,6 +30,7 @@ def run_docker(args):
      cmd = [
          'docker', 'run',
          '--interactive',
+        '--tty',
          '--volume', f'{os.getcwd()}:/src',
          '--workdir', '/src',
          '--user', f'{uid}:{gid}'


I'll send a v2 next week, but I'll wait a bit for any feedback first.

Thanks,
Guillaume

Re: [PATCH v1 1/2] scripts: add tool to run containerized builds

[Onur Özkan]

Hi Guillaume,

Excellent work! Just one note from my side so far:

On Wed, 10 Dec 2025 14:58:28 +0100
Guillaume Tucker <gtucker@gtucker.io> wrote:

> Add a 'scripts/container' tool written in Python to run any command in
> the source tree from within a container.  This can typically be used
> to call 'make' with a compiler toolchain image to run reproducible
> builds but any arbitrary command can be run too.  Only Docker and
> Podman are supported for this initial version.
> 
> Cc: Nathan Chancellor <nathan@kernel.org>
> Cc: Miguel Ojeda <ojeda@kernel.org>
> Link:
> https://lore.kernel.org/all/affb7aff-dc9b-4263-bbd4-a7965c19ac4e@gtucker.io/
> Signed-off-by: Guillaume Tucker <gtucker@gtucker.io> ---
>  scripts/container | 112
> ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 112
> insertions(+) create mode 100755 scripts/container
> 
> diff --git a/scripts/container b/scripts/container
> new file mode 100755
> index 000000000000..74644ac33685
> --- /dev/null
> +++ b/scripts/container
> @@ -0,0 +1,112 @@
> +#!/bin/env python3

By default, this will not work on NixOS because /bin/env is
not a valid path.

It will fail like this:

	$ cat something
	#!/bin/env python3
	
	$ ./something
	zsh: ./something: bad interpreter: /bin/env: no such file or
	directory

Is there a reason for not using /usr/bin/env?

> +# SPDX-License-Identifier: GPL-2.0-only
> +# Copyright (C) 2025 Guillaume Tucker
> +
> +"""Containerized builds"""
> +
> +import argparse
> +import logging
> +import os
> +import subprocess
> +import sys
> +
> +
> +def get_logger(verbose):
> +    """Set up a logger with the appropriate level"""
> +    logger = logging.getLogger('container')
> +    handler = logging.StreamHandler()
> +    handler.setFormatter(logging.Formatter(
> +        fmt='[container {levelname}] {message}', style='{'
> +    ))
> +    logger.addHandler(handler)
> +    logger.setLevel(logging.DEBUG if verbose is True else
> logging.INFO)
> +    return logger
> +
> +
> +def run_docker(args):
> +    """Run a command in a Docker container"""
> +    uid = args.uid or os.getuid()
> +    gid = args.gid or args.uid or os.getgid()
> +    cmd = [
> +        'docker', 'run',
> +        '--interactive',
> +        '--volume', f'{os.getcwd()}:/src',
> +        '--workdir', '/src',
> +        '--user', f'{uid}:{gid}'
> +    ]
> +    if args.env_file:
> +        cmd += ['--env-file', args.env_file]
> +    cmd.append(args.image)
> +    cmd += args.cmd
> +    return subprocess.call(cmd)
> +
> +
> +def run_podman(args):
> +    """Run a command in a Podman container"""
> +    uid = args.uid or 1000
> +    gid = args.gid or args.uid or 1000
> +    cmd = [
> +        'podman', 'run',
> +        '--interactive',
> +        '--volume', f'{os.getcwd()}:/src',
> +        '--workdir', '/src',
> +        '--userns', f'keep-id:uid={uid},gid={gid}',
> +    ]
> +    if args.env_file:
> +        cmd += ['--env-file', args.env_file]
> +    cmd.append(args.image)
> +    cmd += args.cmd
> +    return subprocess.call(cmd)
> +
> +
> +def main(args):
> +    """Main entry point for the container tool"""
> +    logger = get_logger(args.verbose)
> +    logger.debug("runtime=%s, image=%s", args.runtime, args.image)
> +    runtimes = {
> +        'docker': run_docker,
> +        'podman': run_podman,
> +    }
> +    handler = runtimes.get(args.runtime)
> +    if not handler:
> +        logger.error("Unknown container runtime: %s", args.runtime)
> +        return 1
> +    try:
> +        return handler(args)
> +    except KeyboardInterrupt:
> +        logger.error("aborted")
> +        return 1
> +
> +
> +if __name__ == '__main__':
> +    parser = argparse.ArgumentParser("Containerized builds")
> +    parser.add_argument(
> +        '-e', '--env-file',
> +        help="Path to an environment file to load in the container."
> +    )
> +    parser.add_argument(
> +        '-g', '--gid',
> +        help="Group ID to use inside the container."
> +    )
> +    parser.add_argument(
> +        '-i', '--image', default='gcc',
> +        help="Container image, default is gcc."
> +    )
> +    parser.add_argument(
> +        '-r', '--runtime', choices=['docker', 'podman'],
> default='docker',
> +        help="Container runtime, default is docker."
> +    )
> +    parser.add_argument(
> +        '-u', '--uid',
> +        help="User ID to use inside the container.  If the -g option
> is not"
> +        "specified, the user ID will also be used for the group ID."
> +    )
> +    parser.add_argument(
> +        '-v', '--verbose', action='store_true',
> +        help="Enable verbose output."
> +    )
> +    parser.add_argument(
> +        'cmd', nargs='+',
> +        help="Command to run in the container"
> +    )
> +    sys.exit(main(parser.parse_args(sys.argv[1:])))

-Onur

Re: [PATCH v1 1/2] scripts: add tool to run containerized builds

[Guillaume Tucker]

Hi Onur,

On 15/12/2025 10:24 am, Onur Özkan wrote:
> Hi Guillaume,
> 
> Excellent work! Just one note from my side so far:

Thanks for the review!

> On Wed, 10 Dec 2025 14:58:28 +0100
> Guillaume Tucker<gtucker@gtucker.io> wrote:
> 
>> Add a 'scripts/container' tool written in Python to run any command in
>> the source tree from within a container.  This can typically be used
>> to call 'make' with a compiler toolchain image to run reproducible
>> builds but any arbitrary command can be run too.  Only Docker and
>> Podman are supported for this initial version.
>>
>> Cc: Nathan Chancellor<nathan@kernel.org>
>> Cc: Miguel Ojeda<ojeda@kernel.org>
>> Link:
>> https://lore.kernel.org/all/affb7aff-dc9b-4263-bbd4- 
>> a7965c19ac4e@gtucker.io/
>> Signed-off-by: Guillaume Tucker<gtucker@gtucker.io> ---
>>   scripts/container | 112
>> ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 112
>> insertions(+) create mode 100755 scripts/container
>>
>> diff --git a/scripts/container b/scripts/container
>> new file mode 100755
>> index 000000000000..74644ac33685
>> --- /dev/null
>> +++ b/scripts/container
>> @@ -0,0 +1,112 @@
>> +#!/bin/env python3
> By default, this will not work on NixOS because /bin/env is
> not a valid path.
> 
> It will fail like this:
> 
> 	$ cat something
> 	#!/bin/env python3
> 	
> 	$ ./something
> 	zsh: ./something: bad interpreter: /bin/env: no such file or
> 	directory
> 
> Is there a reason for not using /usr/bin/env?

Ah sorry, my bad.  I initially started writing this as a shell script
using /bin/sh and typed it wrong when changing to Python.  So I'll
fix it in v2, thanks for flagging this (pylint didn't...).

Another change I want to make is to drop the default image as 'gcc'
doesn't really help.  If the user hasn't set a custom tag, it will
pull some generic image from docker.io which won't have all the tools
needed to build a kernel.  So making the -i option required or
turning it into a positional argument would be better than some
implicit behaviour.  I'll start a separate thread with Konstantin and
Arnd about hosting kernel.org toolchain container images as having
that should make the tool much more useful and we might set valid
default values e.g. kernel.org/gcc.

Cheers,
Guillaume

Re: [Automated-testing] [PATCH v1 1/2] scripts: add tool to run containerized builds

[David Gow]

[-- Attachment #1: Type: text/plain, Size: 1028 bytes --]

On Wed, 10 Dec 2025 at 21:58, Guillaume Tucker via
lists.yoctoproject.org <gtucker=gtucker.io@lists.yoctoproject.org>
wrote:
>
> Add a 'scripts/container' tool written in Python to run any command in
> the source tree from within a container.  This can typically be used
> to call 'make' with a compiler toolchain image to run reproducible
> builds but any arbitrary command can be run too.  Only Docker and
> Podman are supported for this initial version.
>
> Cc: Nathan Chancellor <nathan@kernel.org>
> Cc: Miguel Ojeda <ojeda@kernel.org>
> Link: https://lore.kernel.org/all/affb7aff-dc9b-4263-bbd4-a7965c19ac4e@gtucker.io/
> Signed-off-by: Guillaume Tucker <gtucker@gtucker.io>
> ---

I gave this a go, and am liking it so far. My only real complaints are
that the defaults don't totally match my prejudices. :-)

Having a good default container, and perhaps falling back
automatically to podman if docker isn't running (or just defaulting to
podman) would make this very convenient for one-line
tests/reproducers.

-- David

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Re: [Automated-testing] [PATCH v1 1/2] scripts: add tool to run containerized builds

[Guillaume Tucker]

Hello David,

On 17/12/2025 10:56 am, David Gow wrote:
> On Wed, 10 Dec 2025 at 21:58, Guillaume Tucker via
> lists.yoctoproject.org <gtucker=gtucker.io@lists.yoctoproject.org>
> wrote:
>>
>> Add a 'scripts/container' tool written in Python to run any command in
>> the source tree from within a container.  This can typically be used
>> to call 'make' with a compiler toolchain image to run reproducible
>> builds but any arbitrary command can be run too.  Only Docker and
>> Podman are supported for this initial version.
>>
>> Cc: Nathan Chancellor <nathan@kernel.org>
>> Cc: Miguel Ojeda <ojeda@kernel.org>
>> Link: https://lore.kernel.org/all/affb7aff-dc9b-4263-bbd4-a7965c19ac4e@gtucker.io/
>> Signed-off-by: Guillaume Tucker <gtucker@gtucker.io>
>> ---
> 
> I gave this a go, and am liking it so far. My only real complaints are
> that the defaults don't totally match my prejudices. :-)
> 
> Having a good default container, and perhaps falling back
> automatically to podman if docker isn't running (or just defaulting to
> podman) would make this very convenient for one-line
> tests/reproducers.

Many thanks for your feedback, I'm glad that worked for you.

Yes, the default 'gcc' image doesn't actually work in practice.  I've
proposed something else in another email to drop the default for now
but aim to provide "first-party" container images using kernel.org
toolchains which may give us some useful default later on.

Then good point about the default container runtime, I'll update the
logic to automatically look for Docker and Podman - basically iterate
through the supported runtimes - in the v2.

Cheers,
Guillaume

Re: [PATCH v1 1/2] scripts: add tool to run containerized builds

[Nathan Chancellor]

Hi Guillaume,

On Wed, Dec 10, 2025 at 02:58:28PM +0100, Guillaume Tucker wrote:
> Add a 'scripts/container' tool written in Python to run any command in
> the source tree from within a container.  This can typically be used
> to call 'make' with a compiler toolchain image to run reproducible
> builds but any arbitrary command can be run too.  Only Docker and
> Podman are supported for this initial version.
> 
> Cc: Nathan Chancellor <nathan@kernel.org>
> Cc: Miguel Ojeda <ojeda@kernel.org>
> Link: https://lore.kernel.org/all/affb7aff-dc9b-4263-bbd4-a7965c19ac4e@gtucker.io/
> Signed-off-by: Guillaume Tucker <gtucker@gtucker.io>

Overall, I like the concept here. It is simple and should be relatively
easy for people to drive. I think having some short quick examples (or a
link to the Documentation file that inclues them) would be good in case
people stumble across the script first.

One initial comment (or perhaps feature request) would be handling O= /
KBUILD_OUTPUT for building out of tree. It may be a little complicated
for mounting the build directory into the container but it might make it
easier for folks who build out of tree to use.

> ---
>  scripts/container | 112 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 112 insertions(+)
>  create mode 100755 scripts/container
> 
> diff --git a/scripts/container b/scripts/container
> new file mode 100755
> index 000000000000..74644ac33685
> --- /dev/null
> +++ b/scripts/container
> @@ -0,0 +1,112 @@
> +#!/bin/env python3
> +# SPDX-License-Identifier: GPL-2.0-only
> +# Copyright (C) 2025 Guillaume Tucker
> +
> +"""Containerized builds"""
> +
> +import argparse
> +import logging
> +import os
> +import subprocess
> +import sys
> +
> +
> +def get_logger(verbose):
> +    """Set up a logger with the appropriate level"""
> +    logger = logging.getLogger('container')
> +    handler = logging.StreamHandler()
> +    handler.setFormatter(logging.Formatter(
> +        fmt='[container {levelname}] {message}', style='{'
> +    ))
> +    logger.addHandler(handler)
> +    logger.setLevel(logging.DEBUG if verbose is True else logging.INFO)
> +    return logger
> +
> +
> +def run_docker(args):
> +    """Run a command in a Docker container"""
> +    uid = args.uid or os.getuid()
> +    gid = args.gid or args.uid or os.getgid()
> +    cmd = [
> +        'docker', 'run',
> +        '--interactive',
> +        '--volume', f'{os.getcwd()}:/src',

Is there a minimum python version required for this? If not, I would
prefer using pathlib here:

  from pathlib import Path

then

  Path.cwd()

> +        '--workdir', '/src',
> +        '--user', f'{uid}:{gid}'
> +    ]
> +    if args.env_file:
> +        cmd += ['--env-file', args.env_file]
> +    cmd.append(args.image)
> +    cmd += args.cmd
> +    return subprocess.call(cmd)
> +
> +
> +def run_podman(args):
> +    """Run a command in a Podman container"""
> +    uid = args.uid or 1000
> +    gid = args.gid or args.uid or 1000

Why 1000 instead of using getuid() and getgid() as above?

> +    cmd = [
> +        'podman', 'run',
> +        '--interactive',
> +        '--volume', f'{os.getcwd()}:/src',
> +        '--workdir', '/src',
> +        '--userns', f'keep-id:uid={uid},gid={gid}',
> +    ]
> +    if args.env_file:
> +        cmd += ['--env-file', args.env_file]
> +    cmd.append(args.image)
> +    cmd += args.cmd
> +    return subprocess.call(cmd)

Most of these two functions are the same. Maybe they could be abstracted
into a simple class so that most of the logic could be shared between
the two implementations? That also might simplify main() a bit and make
fulfilling David's request a little simpler as well.

> +def main(args):
> +    """Main entry point for the container tool"""
> +    logger = get_logger(args.verbose)
> +    logger.debug("runtime=%s, image=%s", args.runtime, args.image)
> +    runtimes = {
> +        'docker': run_docker,
> +        'podman': run_podman,
> +    }
> +    handler = runtimes.get(args.runtime)
> +    if not handler:
> +        logger.error("Unknown container runtime: %s", args.runtime)
> +        return 1
> +    try:
> +        return handler(args)
> +    except KeyboardInterrupt:
> +        logger.error("aborted")
> +        return 1
> +
> +
> +if __name__ == '__main__':
> +    parser = argparse.ArgumentParser("Containerized builds")
> +    parser.add_argument(
> +        '-e', '--env-file',
> +        help="Path to an environment file to load in the container."
> +    )

Is there documentation for how an environment file should be formatter?

> +    parser.add_argument(
> +        '-g', '--gid',
> +        help="Group ID to use inside the container."
> +    )
> +    parser.add_argument(
> +        '-i', '--image', default='gcc',
> +        help="Container image, default is gcc."
> +    )
> +    parser.add_argument(
> +        '-r', '--runtime', choices=['docker', 'podman'], default='docker',
> +        help="Container runtime, default is docker."
> +    )
> +    parser.add_argument(
> +        '-u', '--uid',
> +        help="User ID to use inside the container.  If the -g option is not"
> +        "specified, the user ID will also be used for the group ID."
> +    )
> +    parser.add_argument(
> +        '-v', '--verbose', action='store_true',
> +        help="Enable verbose output."
> +    )
> +    parser.add_argument(
> +        'cmd', nargs='+',
> +        help="Command to run in the container"
> +    )
> +    sys.exit(main(parser.parse_args(sys.argv[1:])))
> -- 
> 2.47.3
> 

Re: [PATCH v1 1/2] scripts: add tool to run containerized builds

[Nathan Chancellor]

On Fri, Dec 19, 2025 at 12:47:48PM -0700, Nathan Chancellor wrote:
> Most of these two functions are the same. Maybe they could be abstracted
> into a simple class so that most of the logic could be shared between
> the two implementations? That also might simplify main() a bit and make
> fulfilling David's request a little simpler as well.

Sigh, this is what I get for working through my inbox bottom up since I
see that you did this in v2 :) looks good, I will give a couple more
comments there.

[PATCH v1 2/2] Documentation: dev-tools: add container.rst page

[Guillaume Tucker]

Add a dev-tools/container.rst documentation page for the
scripts/container tool.  This covers the basic usage with additional
information about environment variables and user IDs.  It also
includes a number of practical examples with a reference to the
experimental kernel.org toolchain images.

Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Guillaume Tucker <gtucker@gtucker.io>
---
 Documentation/dev-tools/container.rst | 175 ++++++++++++++++++++++++++
 Documentation/dev-tools/index.rst     |   1 +
 2 files changed, 176 insertions(+)
 create mode 100644 Documentation/dev-tools/container.rst

diff --git a/Documentation/dev-tools/container.rst b/Documentation/dev-tools/container.rst
new file mode 100644
index 000000000000..2a56f256f648
--- /dev/null
+++ b/Documentation/dev-tools/container.rst
@@ -0,0 +1,175 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+.. Copyright (C) 2025 Guillaume Tucker
+
+====================
+Containerized Builds
+====================
+
+The ``container`` tool can be used to run any command in the kernel source tree
+from within a container.  Doing so facilitates reproducing builds across
+various platforms, for example when a test bot has reported an issue which
+requires a specific version of a compiler or an external test suite.  While
+this can already be done by users who are familiar with containers, having a
+dedicated tool in the kernel tree lowers the barrier to entry by solving common
+problems once and for all (e.g. user id management).  It also makes it easier
+to share an exact command line leading to a particular result.  The main use
+case is likely to be kernel builds but virtually anything can be run: KUnit,
+checkpatch etc. provided a suitable image is available.
+
+
+Options
+=======
+
+Command line syntax::
+
+  scripts/container [OPTION]... CMD...
+
+Available options:
+
+``-e, --env-file ENV_FILE``
+
+    Path to an environment file to load in the container.
+
+``-g, --gid GID``
+
+    Group id to use inside the container.
+
+``-i, --image IMAGE``
+
+    Container image, default is ``gcc``.
+
+``-r, --runtime RUNTIME``
+
+    Container runtime, default is ``docker``.  Supported runtimes: ``docker``,
+    ``podman``.
+
+``-u, --uid UID``
+
+    User id to use inside the container.  If the ``-g`` option is not
+    specified, the user id will also be used for the group id.
+
+``-v, --verbose``
+
+    Enable verbose output.
+
+``-h, --help``
+
+    Show the help message and exit.
+
+
+Usage
+=====
+
+It's entirely up to the user to choose which image to use and the ``CMD``
+arguments are passed directly as an arbitrary command line to run in the
+container.  The tool will take care of mounting the source tree as the current
+working directory and adjust the user and group id as needed.
+
+The container images are provided by the user and selected via the ``-i``
+option.  They will typically include a compiler toolchain to build the kernel
+and as such, the default image tag is set to ``gcc`` to give a convenient way
+of running builds.  Any local image with a GCC compiler toolchain could be
+tagged as ``gcc`` to make it point to it.  For example::
+
+  docker tag my-user/gcc:15 gcc
+
+The container runtime can be selected with the ``-r`` option, which can be
+either Docker or Podman.  Support for other runtimes may be added later
+depending on their popularity among users.
+
+
+Environment Variables
+=====================
+
+Environment variables are not propagated to the container so they have to be
+either defined in the image itself or via the ``-e`` option using an
+environment file.  In some cases it makes more sense to have them defined in
+the Containerfile used to create the image.  For example, a Clang-only compiler
+toolchain image would most likely have ``LLVM=1`` defined.  The local
+environment file is more useful for user-specific variables during development.
+
+Please note that ``make`` options can still be passed on the command line, so
+while this can't be done as the first argument needs to be the executable::
+
+  scripts/container INSTALL_MOD_STRIP=1 make modules_install
+
+this will work::
+
+  scripts/container make modules_install INSTALL_MOD_STRIP=1
+
+
+User IDs
+========
+
+This is an area where the behaviour will vary slightly depending on the
+container runtime.  The goal is to run commands as the user invoking the tool.
+With Podman, a namespace is created to map the current user id to a different
+one in the container (1000 by default).  With Docker, while this is also
+possible with recent versions it requires a special feature to be enabled in
+the daemon so it's not used here for simplicity.  Instead, the container is run
+with the current user id directly.  In both cases, this will provide the same
+file permissions for the kernel source tree mounted as a volume.  The only
+difference is that when using Docker without a namespace, the user id may not
+be the same as the default one set in the image.
+
+Say, we're using an image which sets up a default user with id 1000 and the
+current user calling the ``container`` tool has id 1234.  The kernel source
+tree was checked out by this same user so the files belong to user 1234.  With
+Podman, the container will be running as user id 1000 with a mapping to id 1234
+so that the files from the mounted volume appear to belong to id 1000 inside
+the container.  With Docker and no namespace, the container will be running
+with user id 1234 which can access the files in the volume but not in the user
+1000 home directory.  This shouldn't be an issue when running commands only in
+the kernel tree but it is worth highlighting here as it might matter for
+special corner cases.
+
+
+Examples
+========
+
+The shortest example is to run a basic kernel build using Docker and the
+default ``gcc`` image::
+
+  scripts/container -- make defconfig
+  scripts/container -- make -j$(nproc)
+
+.. note::
+
+   When running a command with options within the container, it should be
+   separated with a double dash ``--`` to not confuse them with the
+   ``container`` tool options.  Simple make targets with no options don't
+   strictly require the double dashes e.g.::
+
+     scripts/container make mrproper
+
+To run ``checkpatch.pl`` in a ``patches`` directory with a generic image::
+
+  scripts/container -i perl:slim-trixie scripts/checkpatch.pl patches/*
+
+To build using the TuxMake Clang image::
+
+  scripts/container -i tuxmake/x86_64_korg-clang -- make LLVM=1 -j$(nproc)
+
+The examples below refer to ``kernel.org`` images which are based on the
+`kernel.org compiler toolchains
+<https://mirrors.edge.kernel.org/pub/tools/>`__.  These aren't (yet) available
+in any public registry but users can build their own locally instead using this
+`experimental repository <https://gitlab.com/gtucker/korg-containers>`__ by
+running ``make PREFIX=kernel.org/``.
+
+To build just ``bzImage`` using Clang::
+
+  scripts/container -i kernel.org/clang -- make bzImage -j$(nproc)
+
+To run KUnit::
+
+  scripts/container -i kernel.org/gcc:kunit -- \
+      tools/testing/kunit/kunit.py \
+          run \
+          --arch=x86_64 \
+          --cross_compile=x86_64-linux-
+
+To build the HTML documentation, which requires the ``kdocs`` image built with
+``make PREFIX=kernel.org/ extra`` as it's not a compiler toolchain::
+
+  scripts/container -i kernel.org/kdocs make htmldocs
diff --git a/Documentation/dev-tools/index.rst b/Documentation/dev-tools/index.rst
index 4b8425e348ab..527a0e4cf2ed 100644
--- a/Documentation/dev-tools/index.rst
+++ b/Documentation/dev-tools/index.rst
@@ -38,6 +38,7 @@ Documentation/process/debugging/index.rst
    gpio-sloppy-logic-analyzer
    autofdo
    propeller
+   container
 
 
 .. only::  subproject and html
-- 
2.47.3