[bug#60632] [PATCH 1/1] services: base: Add extra-env support to guix-configuration.

[bug#60632] [PATCH 1/1] services: base: Add extra-env support to guix-configuration.

[Mathieu Othacehe]

* gnu/services/base.scm (<guix-configuration>)[extra-env]: New field.
(guix-shepherd-service): Honor it.
* doc/guix.texi (Base Services): Document it.
---
Hello,

Here is a small patch to allow defining extra environment variables in the
guix-daemon context.

I intend to use it to set the GUIX_SUBSTITUTE_DEBUG variable to debug
https://issues.guix.gnu.org/48468.

Thanks,

Mathieu

 doc/guix.texi         |  4 ++++
 gnu/services/base.scm | 10 +++++++---
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/doc/guix.texi b/doc/guix.texi
index 293c3016aa..e337945ba7 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -18482,6 +18482,10 @@ herd set-http-proxy guix-daemon
 @item @code{tmpdir} (default: @code{#f})
 A directory path where the @command{guix-daemon} will perform builds.
 
+@item @code{extra-env} (default: @code{'()})
+Environment variables to be set before starting the daemon, as a list of
+@code{key=value} strings.
+
 @end table
 @end deftp
 
diff --git a/gnu/services/base.scm b/gnu/services/base.scm
index 6993e1f174..f29657e86e 100644
--- a/gnu/services/base.scm
+++ b/gnu/services/base.scm
@@ -198,6 +198,7 @@ (define-module (gnu services base)
             guix-configuration-generate-substitute-key?
             guix-configuration-extra-options
             guix-configuration-log-file
+            guix-configuration-extra-env
 
             guix-extension
             guix-extension?
@@ -1654,7 +1655,9 @@ (define-record-type* <guix-configuration>
   (http-proxy       guix-http-proxy               ;string | #f
                     (default #f))
   (tmpdir           guix-tmpdir                   ;string | #f
-                    (default #f)))
+                    (default #f))
+  (extra-env        guix-configuration-extra-env  ;list of strings
+                    (default '())))
 
 (define %default-guix-configuration
   (guix-configuration))
@@ -1710,7 +1713,7 @@ (define (guix-shepherd-service config)
     (guix build-group build-accounts authorize-key? authorized-keys
           use-substitutes? substitute-urls max-silent-time timeout
           log-compression discover? extra-options log-file
-          http-proxy tmpdir chroot-directories)
+          http-proxy tmpdir chroot-directories extra-env)
     (list (shepherd-service
            (documentation "Run the Guix daemon.")
            (provision '(guix-daemon))
@@ -1799,7 +1802,8 @@ (define discover?
                            (if proxy
                                (list (string-append "http_proxy=" proxy)
                                      (string-append "https_proxy=" proxy))
-                               '()))
+                               '())
+                           extra-env)
 
                    #:log-file #$log-file))))
            (stop #~(make-kill-destructor))))))
-- 
2.38.1

[bug#60632] [PATCH 1/1] services: base: Add extra-env support to guix-configuration.

[Maxim Cournoyer]

Hi Mathieu,

Mathieu Othacehe <othacehe@gnu.org> writes:

> * gnu/services/base.scm (<guix-configuration>)[extra-env]: New field.
> (guix-shepherd-service): Honor it.
> * doc/guix.texi (Base Services): Document it.
> ---
> Hello,
>
> Here is a small patch to allow defining extra environment variables in the
> guix-daemon context.
>
> I intend to use it to set the GUIX_SUBSTITUTE_DEBUG variable to debug
> https://issues.guix.gnu.org/48468.

LGTM.

Side topic: I wonder if (with some changes to the daemon -- perhaps in
DerivationGoal::startBuilder) in nix/libstore/build.cc we could leak the
COLUMNS variable to be able to control the Guile builder backtrace
width.

-- 
Thanks,
Maxim

[bug#60632] [PATCH 1/1] services: base: Add extra-env support to guix-configuration.

[Ludovic Courtès]

Hi!

Maxim Cournoyer <maxim.cournoyer@gmail.com> skribis:

> Side topic: I wonder if (with some changes to the daemon -- perhaps in
> DerivationGoal::startBuilder) in nix/libstore/build.cc we could leak the
> COLUMNS variable to be able to control the Guile builder backtrace
> width.

As a rule of thumb, I think we should keep the build environment
unchanged forever—no changes to the set of environment variables and
files/directories present in the build environment.

It’s important because the whole reproducibile-by-construction approach
depends on that.

Ludo’.

configurable guile backtrace in builder (was: services: base: Add extra-env support to guix-configuration)

[Maxim Cournoyer]

+CC guix-devel

Hello!

Ludovic Courtès <ludo@gnu.org> writes:

> Hi!
>
> Maxim Cournoyer <maxim.cournoyer@gmail.com> skribis:
>
>> Side topic: I wonder if (with some changes to the daemon -- perhaps in
>> DerivationGoal::startBuilder) in nix/libstore/build.cc we could leak the
>> COLUMNS variable to be able to control the Guile builder backtrace
>> width.
>
> As a rule of thumb, I think we should keep the build environment
> unchanged forever—no changes to the set of environment variables and
> files/directories present in the build environment.
>
> It’s important because the whole reproducibile-by-construction approach
> depends on that.

I understand it can be risky to change anything on the builder side for
reproducibility.  Would you have an idea of the angle this problem
should be approached from, where the goal is to have a configurable
Guile backtrace width in the builder?

-- 
Thanks,
Maxim

Re: configurable guile backtrace in builder

[Ludovic Courtès]

Hi Maxim,

Maxim Cournoyer <maxim.cournoyer@gmail.com> skribis:

> Ludovic Courtès <ludo@gnu.org> writes:

[...]

>> Maxim Cournoyer <maxim.cournoyer@gmail.com> skribis:
>>
>>> Side topic: I wonder if (with some changes to the daemon -- perhaps in
>>> DerivationGoal::startBuilder) in nix/libstore/build.cc we could leak the
>>> COLUMNS variable to be able to control the Guile builder backtrace
>>> width.
>>
>> As a rule of thumb, I think we should keep the build environment
>> unchanged forever—no changes to the set of environment variables and
>> files/directories present in the build environment.
>>
>> It’s important because the whole reproducibile-by-construction approach
>> depends on that.
>
> I understand it can be risky to change anything on the builder side for
> reproducibility.

It’s not that it’s risky, it’s something we should never do; it’s crucial.

> Would you have an idea of the angle this problem should be approached
> from, where the goal is to have a configurable Guile backtrace width
> in the builder?

How about passing #:env-vars '(("COLUMNS" . "200")) to
‘gexp->derivation’ (in the build system), or adding a phase that sets
that environment variable?

HTH,
Ludo’.

Re: configurable guile backtrace in builder

[Maxim Cournoyer]

Hello,

Ludovic Courtès <ludo@gnu.org> writes:

> Hi Maxim,
>
> Maxim Cournoyer <maxim.cournoyer@gmail.com> skribis:
>
>> Ludovic Courtès <ludo@gnu.org> writes:
>
> [...]
>
>>> Maxim Cournoyer <maxim.cournoyer@gmail.com> skribis:
>>>
>>>> Side topic: I wonder if (with some changes to the daemon -- perhaps in
>>>> DerivationGoal::startBuilder) in nix/libstore/build.cc we could leak the
>>>> COLUMNS variable to be able to control the Guile builder backtrace
>>>> width.
>>>
>>> As a rule of thumb, I think we should keep the build environment
>>> unchanged forever—no changes to the set of environment variables and
>>> files/directories present in the build environment.
>>>
>>> It’s important because the whole reproducibile-by-construction approach
>>> depends on that.
>>
>> I understand it can be risky to change anything on the builder side for
>> reproducibility.
>
> It’s not that it’s risky, it’s something we should never do; it’s crucial.

Okay.

>> Would you have an idea of the angle this problem should be approached
>> from, where the goal is to have a configurable Guile backtrace width
>> in the builder?
>
> How about passing #:env-vars '(("COLUMNS" . "200")) to
> ‘gexp->derivation’ (in the build system), or adding a phase that sets
> that environment variable?

That sounds like a reasonable solution to me!  It's pretty "fixed" while
I would have preferred a user-configurable value, but it's better than
the current situation, so I'd say let's go for it on core-updates!

-- 
Thanks,
Maxim

Re: configurable guile backtrace in builder

[Attila Lendvai]

> How about passing #:env-vars '(("COLUMNS" . "200")) to
> ‘gexp->derivation’ (in the build system), or adding a phase that sets
> that environment variable?


i assume printed guile backtraces should not be part of the normal output of any package.

and then why not introduce an env variable (or some other way) that only affects the backtrace, and nothing else?

-- 
• attila lendvai
• PGP: 963F 5D5F 45C7 DFCD 0A39
--
If the source of fear is the unknown, and fear is the only way to be controlled, then knowledge is the only way to be free.

bug#60632: [PATCH 1/1] services: base: Add extra-env support to guix-configuration.

[Mathieu Othacehe]

Hey,

> As a rule of thumb, I think we should keep the build environment
> unchanged forever—no changes to the set of environment variables and
> files/directories present in the build environment.
>
> It’s important because the whole reproducibile-by-construction approach
> depends on that.

OK, closing then :)

Thanks,

Mathieu