Profile's LD_LIBRARY_PATH by default

Profile's LD_LIBRARY_PATH by default

[Sébastien Lerique]

Dear all,

This question could stem from a simpler example, but I think in 
this case it doesn't change much. So I'll go with my use case:

While running a racket program which uses OpenCV, I realised that 
my LD_LIBRARY_PATH does not contain my user's profile libs. I have 
`libopencv*.so` in `~/.guix-profile/lib/`, but running a racket 
program which needs that fails:

```
$ racket capture.rkt
ffi-lib: couldn't open "libopencv_core.so" (libopencv_core.so: 
cannot open shared object file: No such file or directory)
```

While running

```
env LD_LIBRARY_PATH=/home/sl/.guix-profile/lib/ racket capture.rkt
```

works.

(Also, this <http://0x0.st/ik3s.txt> is the output of `env 
LD_DEBUG=libs racket capture.rkt`.)

Is this normal behaviour, i.e. that the path to dynamic libs 
installed in my user profile should be manually configured in my 
shell startup scripts? Should this not be included in 
`~/.guix-profile/etc/profile`?

Thanks all, and best wishes!
Sébastien

Re: Profile's LD_LIBRARY_PATH by default

[david larsson]

On 2020-10-28 13:49, Sébastien Lerique wrote:
> Dear all,
> 
> This question could stem from a simpler example, but I think in this
> case it doesn't change much. So I'll go with my use case:
> 
> While running a racket program which uses OpenCV, I realised that my
> LD_LIBRARY_PATH does not contain my user's profile libs. I have
> `libopencv*.so` in `~/.guix-profile/lib/`, but running a racket
> program which needs that fails:
> 
> ```
> $ racket capture.rkt
> ffi-lib: couldn't open "libopencv_core.so" (libopencv_core.so: cannot
> open shared object file: No such file or directory)
> ```
> 
> While running
> 
> ```
> env LD_LIBRARY_PATH=/home/sl/.guix-profile/lib/ racket capture.rkt
> ```
> 
> works.
> 
> (Also, this <http://0x0.st/ik3s.txt> is the output of `env
> LD_DEBUG=libs racket capture.rkt`.)
> 
> Is this normal behaviour, i.e. that the path to dynamic libs installed
> in my user profile should be manually configured in my shell startup
> scripts? Should this not be included in `~/.guix-profile/etc/profile`?
> 
> Thanks all, and best wishes!
> Sébastien

Hi!

I wondered the same, and got answer in the IRC #guix that setting 
LD_LIBRARY_PATH is highly discouraged (unless you have a specific and 
good reason to do so in a specific case - never globally). I a good 
explanation about it here: 
https://web.archive.org/web/20060719201954/http://www.visi.com/~barr/ldpath.html

A good example of how it can go wrong:

"In its startup script[a program called WidgetMan], it sets 
LD_LIBRARY_PATH to point to its copy of Motif so it uses that one when 
it runs. As it happens, WidgetMan is designed to launch other programs 
too. Unfortunately, when WidgetMan launches other apps, they inherit the 
LD_LIBRARY_PATH setting and some Motif based apps now break when run 
from WidgetMan because WidgetMan's Motif is incompatible with (but the 
same library version as) the system Motif library. Bummer!"

Re: Profile's LD_LIBRARY_PATH by default

[Sébastien Lerique]

Hello!

On 29 Oct 2020 at 10:10, david larsson 
<david.larsson@selfhosted.xyz> wrote:
> On 2020-10-28 13:49, Sébastien Lerique wrote:
>> [snip]
>> While running a racket program which uses OpenCV, I realised 
>> that my
>> LD_LIBRARY_PATH does not contain my user's profile libs. I have
>> `libopencv*.so` in `~/.guix-profile/lib/`, but running a racket
>> program which needs that fails:
>> ```
>> $ racket capture.rkt
>> ffi-lib: couldn't open "libopencv_core.so" (libopencv_core.so: 
>> cannot
>> open shared object file: No such file or directory)
>> ```
>> While running
>> ```
>> env LD_LIBRARY_PATH=/home/sl/.guix-profile/lib/ racket 
>> capture.rkt
>> ```
>> works.
>> (Also, this <http://0x0.st/ik3s.txt> is the output of `env
>> LD_DEBUG=libs racket capture.rkt`.)
>> Is this normal behaviour, i.e. that the path to dynamic libs 
>> installed
>> in my user profile should be manually configured in my shell 
>> startup
>> scripts? Should this not be included in 
>> `~/.guix-profile/etc/profile`?

> I wondered the same, and got answer in the IRC #guix that 
> setting
> LD_LIBRARY_PATH is highly discouraged (unless you have a 
> specific and
> good reason to do so in a specific case - never globally). I a 
> good explanation
> about it here:
> https://web.archive.org/web/20060719201954/http://www.visi.com/~barr/ldpath.html
>
> A good example of how it can go wrong:
>
> "In its startup script[a program called WidgetMan], it sets 
> LD_LIBRARY_PATH to
> point to its copy of Motif so it uses that one when it runs. As 
> it happens,
> WidgetMan is designed to launch other programs too. 
> Unfortunately, when
> WidgetMan launches other apps, they inherit the LD_LIBRARY_PATH 
> setting and some
> Motif based apps now break when run from WidgetMan because 
> WidgetMan's Motif is
> incompatible with (but the same library version as) the system 
> Motif library.
> Bummer!"

Yes I see that makes sense. Does this mean that one shouldn't 
install libraries in user profiles?

Or maybe that, if I were to package this racket program, then it 
would depend on `opencv` and set its required lib paths properly 
in its package definition (so work no matter if it's system-wide 
or in a user profile)?

Then, for development, is setting LD_LIBRARY_PATH still the only 
way without installing the lib system-wide?

(that's a lot of questions, apologies!)

Re: Profile's LD_LIBRARY_PATH by default

[david larsson]

On 2020-10-29 10:07, Sébastien Lerique wrote:
> Hello!
> 
> On 29 Oct 2020 at 10:10, david larsson <david.larsson@selfhosted.xyz> 
> wrote:
>> On 2020-10-28 13:49, Sébastien Lerique wrote:
>>> [snip]
>>> While running a racket program which uses OpenCV, I realised that my
>>> LD_LIBRARY_PATH does not contain my user's profile libs. I have
>>> `libopencv*.so` in `~/.guix-profile/lib/`, but running a racket
>>> program which needs that fails:
>>> ```
>>> $ racket capture.rkt
>>> ffi-lib: couldn't open "libopencv_core.so" (libopencv_core.so: cannot
>>> open shared object file: No such file or directory)
>>> ```
>>> While running
>>> ```
>>> env LD_LIBRARY_PATH=/home/sl/.guix-profile/lib/ racket capture.rkt
>>> ```
>>> works.
>>> (Also, this <http://0x0.st/ik3s.txt> is the output of `env
>>> LD_DEBUG=libs racket capture.rkt`.)
>>> Is this normal behaviour, i.e. that the path to dynamic libs 
>>> installed
>>> in my user profile should be manually configured in my shell startup
>>> scripts? Should this not be included in 
>>> `~/.guix-profile/etc/profile`?
> 
>> I wondered the same, and got answer in the IRC #guix that setting
>> LD_LIBRARY_PATH is highly discouraged (unless you have a specific and
>> good reason to do so in a specific case - never globally). I a good 
>> explanation
>> about it here:
>> https://web.archive.org/web/20060719201954/http://www.visi.com/~barr/ldpath.html
>> 
>> A good example of how it can go wrong:
>> 
>> "In its startup script[a program called WidgetMan], it sets 
>> LD_LIBRARY_PATH to
>> point to its copy of Motif so it uses that one when it runs. As it 
>> happens,
>> WidgetMan is designed to launch other programs too. Unfortunately, 
>> when
>> WidgetMan launches other apps, they inherit the LD_LIBRARY_PATH 
>> setting and some
>> Motif based apps now break when run from WidgetMan because WidgetMan's 
>> Motif is
>> incompatible with (but the same library version as) the system Motif 
>> library.
>> Bummer!"
> 
> Yes I see that makes sense. Does this mean that one shouldn't install
> libraries in user profiles?

Not necessarily - it shouldn't hurt anway IIUC. Though I assume it is 
more common to install libraries when you use guix environment or guix 
profile.

> 
> Or maybe that, if I were to package this racket program, then it would
> depend on `opencv` and set its required lib paths properly in its
> package definition (so work no matter if it's system-wide or in a user
> profile)?

IIUC, yes, through package inputs and then the build-system usually 
finds the path for you.

> Then, for development, is setting LD_LIBRARY_PATH still the only way
> without installing the lib system-wide?

It is possibly the easiest way, but perhaps not the guix-iest way.

Please someone correct me if Im wrong here:

For development you can use guix environment or guix-profile and 
possibly even grafts if you want to develop against newer versions of 
opency.

Say you want to test updating the opency package in a profile created by 
guix package -m manifest.scm -p ~/guix-profiles/dev-profile; the new 
opency version can be grafted onto your racket package X (or all 
packages in the profile depending on opency) without rebuilding X, by 
adding "(replacement opency-fixed)" in the opency package definition in 
the profile manifest. On the next package update for the profile (i.e. 
guix package -m manifest-with-replacement.scm -p 
~/guix-profile/dev-profile) all dependencies of opency would be updated 
(such as your package X). The "manifest.scm" file is a package module 
that contains; the definition of opency with "(replacement 
opency-fixed)", the package definition for "opency-fixed", definition of 
X, and also any other packages you need to test.

see here: https://guix.gnu.org/manual/en/html_node/Security-Updates.html
and here: 
https://guix.gnu.org/manual/en/html_node/Invoking-guix-environment.html

> 
> (that's a lot of questions, apologies!)

No problem :-)