minimal "zero conf" build dockerfiles for fedora:latest and alpine:latest

minimal "zero conf" build dockerfiles for fedora:latest and alpine:latest

[John Snow]

I wanted to know what the minimal setup required was to replicate the 
compilation instructions featured on https://www.qemu.org/download/#source

 > wget https://download.qemu.org/qemu-5.2.0.tar.xz
 > tar xvJf qemu-5.2.0.tar.xz
 > cd qemu-5.2.0
 > ./configure
 > make

For fedora:latest, I found that to be:

----

FROM fedora:latest

ENV PACKAGES \
       wget \
       xz \
       ninja-build \
       gcc \
       glib2-devel \
       pixman-devel \
       bzip2 \
       diffutils \
       perl

ENV QEMU_CONFIGURE_OPTS ""

RUN dnf install -y $PACKAGES && \
     rpm -q $PACKAGES | sort > /packages.txt

RUN wget https://download.qemu.org/qemu-5.2.0.tar.xz && \
     tar xvJf qemu-5.2.0.tar.xz

WORKDIR /qemu-5.2.0
RUN ./configure $QEMU_CONFIGURE_OPTS && \
     make -j9

----

Notes:

- our configure file suggests bzip2 is an optional dependency (It's set 
to 'auto') but meson will error out if it is not present at 
configuration time:

     ../pc-bios/meson.build:5:2: ERROR: Program 'bzip2' not found

- diffutils is required for the qapi-schema test, which runs at build time.

- early on in the build process, an error "bash: find: command not 
found" can be seen, but it doesn't seem to cause a failure otherwise.

- perl is not declared as a hard pre-requisite during configure time, 
but the build will error out if it is not present:

[254/8314] Generating texture-blit-frag.h with a meson_exe.py custom command
FAILED: ui/shader/texture-blit-frag.h
/usr/bin/python3 /qemu-5.2.0/meson/meson.py --internal exe --capture 
ui/shader/texture-blit-frag.h -- /usr/bin/env perl 
/qemu-5.2.0/scripts/shaderinclude.pl ../ui/shader/texture-blit.frag
/usr/bin/env: ‘perl’: No such file or directory



I wanted to try with alpine for the sake of a dependency audit. It isn't 
quite "zero conf", but I did get it working by disabling linux-user:

----

FROM alpine:latest

ENV PACKAGES \
     wget \
     xz \
     python3 \
     ninja \
     gcc \
     musl-dev \
     pkgconfig \
     glib-dev \
     pixman-dev \
     make \
     bash \
     perl

ENV QEMU_CONFIGURE_OPTS --disable-linux-user

RUN apk add $PACKAGES

RUN wget https://download.qemu.org/qemu-5.2.0.tar.xz && \
     tar xvJf qemu-5.2.0.tar.xz

WORKDIR /qemu-5.2.0
RUN ./configure $QEMU_CONFIGURE_OPTS && \
     make -j9

----

Notes:

- "ninja" actually installs "samurai", but it appears to work.

- musl seems to work alright, but does throw a ton of warnings. I didn't 
actually run any tests, since they require more dependencies.

- bash has to be installed explicitly. configure/meson do not check for 
it, but the build will fail if they aren't present.

- linux-user binaries can't be compiled because alpine's usage of musl; 
I didn't look much more closely.



Takeaways:

- You really don't need a lot to build a minimal QEMU. Even the alpine 
package list is pretty small.

- meson seems to be handling "absolutely everything is missing" 
environments pretty well.

- There are a scant handful of dependencies that could be added to 
configure, but you are very likely not to be missing them, so it's low 
priority.


--js

Re: minimal "zero conf" build dockerfiles for fedora:latest and alpine:latest

[Thomas Huth]

On 12/01/2021 23.37, John Snow wrote:
> I wanted to know what the minimal setup required was to replicate the 
> compilation instructions featured on https://www.qemu.org/download/#source
[...]
 >      pixman-devel \

pixman is only required for the softmmu and tools targets. If you just build 
the linux-user targets, you can even get rid of this.

[...]
> Notes:
> 
> - our configure file suggests bzip2 is an optional dependency (It's set to 
> 'auto') but meson will error out if it is not present at configuration time:
> 
>      ../pc-bios/meson.build:5:2: ERROR: Program 'bzip2' not found

IIRC it's required for compressing the edk2 firmware images, so if you 
compile without x86 and arm, you don't need it. Maybe it would be good to 
add a check for this to the configure script, too?

> - diffutils is required for the qapi-schema test, which runs at build time.

We should maybe add a check for "diff" to the configure script?

> - early on in the build process, an error "bash: find: command not found" 
> can be seen, but it doesn't seem to cause a failure otherwise.
> 
> - perl is not declared as a hard pre-requisite during configure time, but 
> the build will error out if it is not present:
> 
> [254/8314] Generating texture-blit-frag.h with a meson_exe.py custom command
> FAILED: ui/shader/texture-blit-frag.h
> /usr/bin/python3 /qemu-5.2.0/meson/meson.py --internal exe --capture 
> ui/shader/texture-blit-frag.h -- /usr/bin/env perl 
> /qemu-5.2.0/scripts/shaderinclude.pl ../ui/shader/texture-blit.frag
> /usr/bin/env: ‘perl’: No such file or directory

shaderinclude.pl seems to be pretty small, maybe it could be rewritten in 
python?

> - bash has to be installed explicitly. configure/meson do not check for it, 
> but the build will fail if they aren't present.

IIRC we were able to compile without bash before the meson conversion, just 
some parts like the iotests needed the bash (at least that's why we have a 
check for bash in tests/check-block.sh for example). Where is it failing now?

> - musl seems to work alright, but does throw a ton of warnings. I didn't 
> actually run any tests, since they require more dependencies.
> 
> - linux-user binaries can't be compiled because alpine's usage of musl; I 
> didn't look much more closely.

There were some related patches on the list recently, look for the "Alpine 
Linux build fix and CI pipeline" patch series.

  Thomas

Re: minimal "zero conf" build dockerfiles for fedora:latest and alpine:latest

[Paolo Bonzini]

On 12/01/21 23:37, John Snow wrote:
> - our configure file suggests bzip2 is an optional dependency (It's set 
> to 'auto') but meson will error out if it is not present at 
> configuration time:
> 
>      ../pc-bios/meson.build:5:2: ERROR: Program 'bzip2' not found

Yes, the configure option is for libbzip2, not bzip2.

Perhaps bzip2 could be required only if get_option('install_blobs') is 
true, I don't know.

> FROM alpine:latest
> 
> ENV PACKAGES \
>      wget \
>      xz \
>      python3 \
>      ninja \
>      gcc \
>      musl-dev \
>      pkgconfig \
>      glib-dev \
>      pixman-dev \
>      make \
>      bash \
>      perl
> 
> ENV QEMU_CONFIGURE_OPTS --disable-linux-user
> 
> RUN apk add $PACKAGES
> 
> RUN wget https://download.qemu.org/qemu-5.2.0.tar.xz && \
>      tar xvJf qemu-5.2.0.tar.xz
> 
> WORKDIR /qemu-5.2.0
> RUN ./configure $QEMU_CONFIGURE_OPTS && \
>      make -j9

This should be added to the CI!

> - diffutils is required for the qapi-schema test, which runs at build time. 

This is not required by meson because technically it is not needed 
except for "make check".

Perhaps we could do

-if build_docs
+if build_docs and diff.found()

in tests/qapi-schema/meson.build.

Paolo

Re: minimal "zero conf" build dockerfiles for fedora:latest and alpine:latest

[Paolo Bonzini]

On 13/01/21 07:48, Thomas Huth wrote:
>>
>> [254/8314] Generating texture-blit-frag.h with a meson_exe.py custom 
>> command
>> FAILED: ui/shader/texture-blit-frag.h
>> /usr/bin/python3 /qemu-5.2.0/meson/meson.py --internal exe --capture 
>> ui/shader/texture-blit-frag.h -- /usr/bin/env perl 
>> /qemu-5.2.0/scripts/shaderinclude.pl ../ui/shader/texture-blit.frag
>> /usr/bin/env: ‘perl’: No such file or directory
> 
> shaderinclude.pl seems to be pretty small, maybe it could be rewritten 
> in python?

Probably, but "make check" also requires Perl for the TAP driver.  I do 
have plans for using "meson test" instead, *however* there's also the 
other idea I've floated of parsing the command line with Perl:

https://patchew.org/QEMU/20210107140039.467969-1-pbonzini@redhat.com/20210107140039.467969-9-pbonzini@redhat.com/

(reviews welcome by the way).

I don't like Perl really, but there's a chicken-and-egg problem between 
detecting Python and using it to print the configure help script.  For 
configure-time tasks, Perl has the advantage that "#! /usr/bin/env perl" 
just works.

>> - bash has to be installed explicitly. configure/meson do not check 
>> for it, but the build will fail if they aren't present.
> 
> IIRC we were able to compile without bash before the meson conversion, 
> just some parts like the iotests needed the bash (at least that's why we 
> have a check for bash in tests/check-block.sh for example). Where is it 
> failing now?

It's failing due to

SHELL = /usr/bin/env bash -o pipefail

introduced in 5.2 (but not related to the Meson conversion)

     commit 3bf4583580ab705de1beff6222e934239c3a0356
     Author: Paolo Bonzini <pbonzini@redhat.com>
     Date:   Wed Oct 14 07:35:13 2020 -0400

     make: run shell with pipefail

     Without pipefail, it is possible to miss failures if the recipes
     include pipes.

     Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
     Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Paolo

Re: minimal "zero conf" build dockerfiles for fedora:latest and alpine:latest

[Gerd Hoffmann]

  Hi,

> I don't like Perl really, but there's a chicken-and-egg problem between
> detecting Python and using it to print the configure help script.  For
> configure-time tasks, Perl has the advantage that "#! /usr/bin/env perl"
> just works.

Assuming perl is actually installed, the world seems to shift to python.
On a minimal fedora install python is present but perl is not ...

On the other hand git depends on perl, so it is probably pretty hard to
find a developer workstation without perl installed, so maybe that
doesn't matter much for the time being.

take care,
  Gerd

Re: minimal "zero conf" build dockerfiles for fedora:latest and alpine:latest

[Philippe Mathieu-Daudé]

On 1/13/21 11:09 AM, Gerd Hoffmann wrote:
>   Hi,
> 
>> I don't like Perl really, but there's a chicken-and-egg problem between
>> detecting Python and using it to print the configure help script.  For
>> configure-time tasks, Perl has the advantage that "#! /usr/bin/env perl"
>> just works.
> 
> Assuming perl is actually installed, the world seems to shift to python.
> On a minimal fedora install python is present but perl is not ...
> 
> On the other hand git depends on perl, so it is probably pretty hard to
> find a developer workstation without perl installed, so maybe that
> doesn't matter much for the time being.

There is also the new configure-parse-buildoptions.pl script Paolo
wants to add:
https://www.mail-archive.com/qemu-devel@nongnu.org/msg770651.html

Re: minimal "zero conf" build dockerfiles for fedora:latest and alpine:latest

[Paolo Bonzini]

On 13/01/21 11:29, Philippe Mathieu-Daudé wrote:
> On 1/13/21 11:09 AM, Gerd Hoffmann wrote:
>>    Hi,
>>
>>> I don't like Perl really, but there's a chicken-and-egg problem between
>>> detecting Python and using it to print the configure help script.  For
>>> configure-time tasks, Perl has the advantage that "#! /usr/bin/env perl"
>>> just works.
>>
>> Assuming perl is actually installed, the world seems to shift to python.
>> On a minimal fedora install python is present but perl is not ...
>>
>> On the other hand git depends on perl, so it is probably pretty hard to
>> find a developer workstation without perl installed, so maybe that
>> doesn't matter much for the time being.
> 
> There is also the new configure-parse-buildoptions.pl script Paolo
> wants to add:
> https://www.mail-archive.com/qemu-devel@nongnu.org/msg770651.html
> 

Yes, that's what I was referring to.  shaderinclude.pl could be 
converted easily to Python, and I do support in general moving from Perl 
to Python.  For configure-parse-buildoptions.pl I viewed Perl as more of 
a necessary evil.

In the case of scripts/tap-driver.pl, the plan is to use "meson test" 
instead as soon as it becomes featureful enough.  I have already 
switched my private branch to it, the upstream meson work is tracked at 
https://github.com/mesonbuild/meson/issues/7830.

Paolo

Re: minimal "zero conf" build dockerfiles for fedora:latest and alpine:latest

[John Snow]

On 1/13/21 1:48 AM, Thomas Huth wrote:
> On 12/01/2021 23.37, John Snow wrote:
>> I wanted to know what the minimal setup required was to replicate the 
>> compilation instructions featured on 
>> https://www.qemu.org/download/#source
> [...]
>  >      pixman-devel \
> 
> pixman is only required for the softmmu and tools targets. If you just 
> build the linux-user targets, you can even get rid of this.
> 

Sure; the intent was to figure out what happens if you run the 
instructions from the website without explicitly disabling anything.

What will you get by default?

softmmu by default is probably a pretty reasonable thing to want to 
build, so I'd say pixman will have to stick around in our minimal 
dependency list for now; though if we were to translate this experiment 
to the website, it'd be worth noting that pixman is only required for 
some, but not all, binaries like you say.

(If there was some way to build softmmu without pixman by default, that 
would be pretty interesting, though. I suppose it would involve 
disabling all spice/vnc/graphics devices entirely? It doesn't seem 
tremendously important, but pixman does stick out as the lone very 
particular dependency for a minimal build.)

> [...]
>> Notes:
>>
>> - our configure file suggests bzip2 is an optional dependency (It's 
>> set to 'auto') but meson will error out if it is not present at 
>> configuration time:
>>
>>      ../pc-bios/meson.build:5:2: ERROR: Program 'bzip2' not found
> 
> IIRC it's required for compressing the edk2 firmware images, so if you 
> compile without x86 and arm, you don't need it. Maybe it would be good 
> to add a check for this to the configure script, too?
> 

It already is erroring out when meson runs, so I think it's probably 
fine. Just something to document.

>> - diffutils is required for the qapi-schema test, which runs at build 
>> time.
> 
> We should maybe add a check for "diff" to the configure script?
> 

It's in tests/qapi-schema/meson.build already, so I think it's sufficient.

>> - early on in the build process, an error "bash: find: command not 
>> found" can be seen, but it doesn't seem to cause a failure otherwise.
>>
>> - perl is not declared as a hard pre-requisite during configure time, 
>> but the build will error out if it is not present:
>>
>> [254/8314] Generating texture-blit-frag.h with a meson_exe.py custom 
>> command
>> FAILED: ui/shader/texture-blit-frag.h
>> /usr/bin/python3 /qemu-5.2.0/meson/meson.py --internal exe --capture 
>> ui/shader/texture-blit-frag.h -- /usr/bin/env perl 
>> /qemu-5.2.0/scripts/shaderinclude.pl ../ui/shader/texture-blit.frag
>> /usr/bin/env: ‘perl’: No such file or directory
> 
> shaderinclude.pl seems to be pretty small, maybe it could be rewritten 
> in python?
> 

Maybe; Paolo has replied to you as well, but this is just the first perl 
script that so happens to run. There might be others.

Drawing down on perl long-term is probably nice to do, but it's probably 
not a priority. For now, we have both perl and python as build 
dependencies. Let's document and move on.

>> - bash has to be installed explicitly. configure/meson do not check 
>> for it, but the build will fail if they aren't present.
> 
> IIRC we were able to compile without bash before the meson conversion, 
> just some parts like the iotests needed the bash (at least that's why we 
> have a check for bash in tests/check-block.sh for example). Where is it 
> failing now?
> 
>> - musl seems to work alright, but does throw a ton of warnings. I 
>> didn't actually run any tests, since they require more dependencies.
>>
>> - linux-user binaries can't be compiled because alpine's usage of 
>> musl; I didn't look much more closely.
> 
> There were some related patches on the list recently, look for the 
> "Alpine Linux build fix and CI pipeline" patch series.
> 

Glad to see someone else thought it would be worthwhile to support 
Alpine. There may be interesting use cases for building alpine QEMU 
containers that are configured for extremely particular use cases, to be 
deployed as a utility.

--js

Re: minimal "zero conf" build dockerfiles for fedora:latest and alpine:latest

[John Snow]

On 1/13/21 5:09 AM, Gerd Hoffmann wrote:
>    Hi,
> 
>> I don't like Perl really, but there's a chicken-and-egg problem between
>> detecting Python and using it to print the configure help script.  For
>> configure-time tasks, Perl has the advantage that "#! /usr/bin/env perl"
>> just works.
> 
> Assuming perl is actually installed, the world seems to shift to python.
> On a minimal fedora install python is present but perl is not ...
> 
> On the other hand git depends on perl, so it is probably pretty hard to
> find a developer workstation without perl installed, so maybe that
> doesn't matter much for the time being.
> 
> take care,
>    Gerd
> 

I agree that it doesn't matter much right now, Though I don't always 
have git installed in containers when I am doing builds. It will become 
more common to encounter environments that are missing "obvious" 
dependencies.

This was just an "FYI" experiment. :)

--js

Re: minimal "zero conf" build dockerfiles for fedora:latest and alpine:latest

[John Snow]

On 1/13/21 3:20 AM, Paolo Bonzini wrote:
> On 12/01/21 23:37, John Snow wrote:
>> - our configure file suggests bzip2 is an optional dependency (It's 
>> set to 'auto') but meson will error out if it is not present at 
>> configuration time:
>>
>>      ../pc-bios/meson.build:5:2: ERROR: Program 'bzip2' not found
> 
> Yes, the configure option is for libbzip2, not bzip2.
> 
> Perhaps bzip2 could be required only if get_option('install_blobs') is 
> true, I don't know.
> 

Oh, right. Library vs tool. Good point.

Yes, we should make the tool required somewhere in the configure jungle.

>> FROM alpine:latest
>>
>> ENV PACKAGES \
>>      wget \
>>      xz \
>>      python3 \
>>      ninja \
>>      gcc \
>>      musl-dev \
>>      pkgconfig \
>>      glib-dev \
>>      pixman-dev \
>>      make \
>>      bash \
>>      perl
>>
>> ENV QEMU_CONFIGURE_OPTS --disable-linux-user
>>
>> RUN apk add $PACKAGES
>>
>> RUN wget https://download.qemu.org/qemu-5.2.0.tar.xz && \
>>      tar xvJf qemu-5.2.0.tar.xz
>>
>> WORKDIR /qemu-5.2.0
>> RUN ./configure $QEMU_CONFIGURE_OPTS && \
>>      make -j9
> 
> This should be added to the CI!
> 

Apparently someone else is working on an Alpine linux patchset, so I 
suppose something like this will be included there.

If not, feel free to take it:

Signed-off-by: John Snow <jsnow@redhat.com>

However, yes, I would like to include some build smoke tests for CI, 
which just cover "configure && make" with the absolute minimum set of 
dependencies possible. We could rebase our more fully fledged tests on 
top of them to share the common layer.

Not a priority for me, but I'm keeping these little dinky dockerfiles 
around to use as smoke tests against fedora:latest, alpine:latest, etc. 
I should likely expand to CentOS stream, debian, and so on to catch 
early breakages.

>> - diffutils is required for the qapi-schema test, which runs at build 
>> time. 
> 
> This is not required by meson because technically it is not needed 
> except for "make check".
> 

Is that true? I was just running "make". qapi-schema test does run at 
build time to make sure that the schema pre-processing occurred correctly.

> Perhaps we could do
> 
> -if build_docs
> +if build_docs and diff.found()
> 
> in tests/qapi-schema/meson.build.
> 
> Paolo
> 

I wasn't building docs, I don't think. (No sphinx and no --enable-docs.)

--js

Re: minimal "zero conf" build dockerfiles for fedora:latest and alpine:latest

[Andrea Bolognani]

On Wed, 2021-01-13 at 13:31 -0500, John Snow wrote:
> On 1/13/21 5:09 AM, Gerd Hoffmann wrote:
> > > I don't like Perl really, but there's a chicken-and-egg problem between
> > > detecting Python and using it to print the configure help script.  For
> > > configure-time tasks, Perl has the advantage that "#! /usr/bin/env perl"
> > > just works.
> > 
> > Assuming perl is actually installed, the world seems to shift to python.
> > On a minimal fedora install python is present but perl is not ...
> > 
> > On the other hand git depends on perl, so it is probably pretty hard to
> > find a developer workstation without perl installed, so maybe that
> > doesn't matter much for the time being.
> 
> I agree that it doesn't matter much right now, Though I don't always 
> have git installed in containers when I am doing builds. It will become 
> more common to encounter environments that are missing "obvious" 
> dependencies.

Note that Fedora has a git-core package that doesn't depend on Perl
while still providing more than enough git for something like a CI
build job.

As a data point, the libvirt project has made it an explicit goal[1]
to remove all usage of Perl in favor of Python. We're not quite there
yet, but at this point there are only a very tiny handful of Perl
scripts remaining in the repository.


[1] https://libvirt.org/strategy.html
-- 
Andrea Bolognani / Red Hat / Virtualization

Re: minimal "zero conf" build dockerfiles for fedora:latest and alpine:latest

[John Snow]

On 1/14/21 6:10 AM, Andrea Bolognani wrote:
> On Wed, 2021-01-13 at 13:31 -0500, John Snow wrote:
>> On 1/13/21 5:09 AM, Gerd Hoffmann wrote:
>>>> I don't like Perl really, but there's a chicken-and-egg problem between
>>>> detecting Python and using it to print the configure help script.  For
>>>> configure-time tasks, Perl has the advantage that "#! /usr/bin/env perl"
>>>> just works.
>>>
>>> Assuming perl is actually installed, the world seems to shift to python.
>>> On a minimal fedora install python is present but perl is not ...
>>>
>>> On the other hand git depends on perl, so it is probably pretty hard to
>>> find a developer workstation without perl installed, so maybe that
>>> doesn't matter much for the time being.
>>
>> I agree that it doesn't matter much right now, Though I don't always
>> have git installed in containers when I am doing builds. It will become
>> more common to encounter environments that are missing "obvious"
>> dependencies.
> 
> Note that Fedora has a git-core package that doesn't depend on Perl
> while still providing more than enough git for something like a CI
> build job.
> 

Good to know. Another point against perl necessarily existing.

> As a data point, the libvirt project has made it an explicit goal[1]
> to remove all usage of Perl in favor of Python. We're not quite there
> yet, but at this point there are only a very tiny handful of Perl
> scripts remaining in the repository.
> 
> 
> [1] https://libvirt.org/strategy.html
> 

It's a good long term goal, I think.

I'm biased, but:

(1) I understand Python very well
(2) I find perl difficult to work with.

I assume that long-term it will be easier to use Python instead of Perl 
for most of our precompiler scripts. Based also somewhat on everyone's 
reaction when someone suggests changes to the checkpatch script, which 
is "Oh, sure, if YOU write it ..."

--js

Re: minimal "zero conf" build dockerfiles for fedora:latest and alpine:latest

[Philippe Mathieu-Daudé]

On 1/13/21 9:20 AM, Paolo Bonzini wrote:
> On 12/01/21 23:37, John Snow wrote:
>> - our configure file suggests bzip2 is an optional dependency (It's
>> set to 'auto') but meson will error out if it is not present at
>> configuration time:
>>
>>      ../pc-bios/meson.build:5:2: ERROR: Program 'bzip2' not found
> 
> Yes, the configure option is for libbzip2, not bzip2.
> 
> Perhaps bzip2 could be required only if get_option('install_blobs') is
> true, I don't know.

Yes, OK.