[PATCH 1/2] gnu: shepherd: Build Shepherd from git.

The rationale for this is that it makes it simpler to start VM's with a

Shepherd that is compiled from a local checkout. This facilitates hacking on

Shepherd itself, and testing it in the Guix init environment, by speeding up

the edit-compile-test cycle.

native-inputs accordingly. Also delete the strip build phase.

---

the first commit works, except when cross-compiling: help2man wants

to run the foreign binary, and fails.

the second commit is a WIP attempt to get the compiled man pages

from the native package when cross compiling. it's not ready,

but i got stuck at needing to gunzip the man pages, and where

to put them to convince the makefile to not execute help2man, etc.

my suggestion is to simply get rid of the not-very-useful

auto generated man page to fix cross-compilation.

if that's not desirable, then the second commit needs to be

polished, or implemented some other way.

gnu/packages/admin.scm | 28 +++++++++++++++++-----------

1 file changed, 17 insertions(+), 11 deletions(-)

---

gnu/packages/admin.scm | 48 +++++++++++++++++++++++++++++++++---------

1 file changed, 38 insertions(+), 10 deletions(-)

The rationale for this is that it makes it simpler to start VM's with a

Shepherd that is compiled from a local checkout. This facilitates hacking on

Shepherd itself, and testing it in the Guix init environment, by speeding up

the edit-compile-test cycle.

native-inputs accordingly. Also delete the strip build phase.

---

i've been running with this commit ever since i first submitted it, but

now it is causing quite a lot of local rebuilds, making it that much more

trouble.

please consider merging it if it makes senes.

note that it was not extensively tested by me WRT cross-compilation, or

non x86_64 platforms.

gnu/packages/admin.scm | 38 +++++++++++++++++++++++---------------

1 file changed, 23 insertions(+), 15 deletions(-)

Ludo, any hope that this gets merged?

i'm trying to debug something in shepherd (the SYSTEM call in shepherd misbehaves, but only when pulled on my server, not in a `guix system vm`). it will once again require me to use a custom shepherd, and pull/rebuild/reconfigure a gazillion times.

as for this patch: the only issue i know is that it cannot be cross compiled because of the help2man call. if you ask me, i would just get rid of that altogether. it's just added complexity for little gain.

--

• attila lendvai

• PGP: 963F 5D5F 45C7 DFCD 0A39

--

“He who flatters a man is his enemy. He who tells him of his faults is his maker.”

— Confucius (551–479 BC)

Hi Attila,

Attila Lendvai <attila@lendvai.name> skribis:

Apologies. I’m not convinced about the patch, mainly because I’ve been

using Shepherd as a channel for testing, which I think makes fine

details about the ‘shepherd’ package in Guix less interesting.

For info on how to do that, see:

https://git.savannah.gnu.org/cgit/shepherd.git/tree/README

The added bonus when doing this is that ‘guix system describe’ tells you

precisely which Shepherd commit you’re using.

WDYT?

Thanks,

Ludo’.

ouch, we've been here before, sorry for my loss of memory!

but after having read the README once again, i'm still not sure how this would work. please confirm my assumption:

if i add shepherd as a channel, then i unavoidably need to issue a `guix pull` (slow!) before i can test any shepherd changes, even if the channel points to a local checkout. also, i need to record any pending changes that i want to test into a git commit.

this is my objective:

- be able to edit files in a shepherd checkout

- issue a command that runs a vm with my shepherd changes included

- keep this cycle reasonably fast to avoid frustration

my ultimate objective:

fix a shepherd-action bug that doesn't manifest in my `guix system vm` tests, only when i pull stuff to my server (slow!). i have zero info on what goes wrong besides a non-zero return code from tar that my action invokes. to gain more info i'm planning to add extensive logging to shepherd, especially around its fork+exec-command calls.

this is how i used to hack shepherd, when i need to test it in its real environment:

i have a guix system test that i have extracted from the guix test suite. it defines an OPERATING-SYSTEM object that is run using `guix system vm`:

a custom shepherd package is defined for this OS object by modifying its SHEPHERD-ROOT-SERVICE-TYPE.

my custom shepherd package inherits from the shepherd package from guix, and replaces its source to point to my own shepherd checkout. for this to work, my local guix contains the patch to compile shepherd from git.

this worked fine, but something broke my setup recently. it was that some heavy packages started to depend on shepherd, which means that if i include my patch to compile shepherd from git, then all those packages need to be recompiled locally, which is pohibitively slow (it's added to the edit-compile-run cycle).

a tangential: i think these new dependencies are only needed for the CLI tools provided by the shepherd package. splitting shepherd into two packages (CLI tools and service) would also resolve this problem of mine.

possible solutions:

1) i learn some better way to hack on shepherd

2) shepherd in guix is compiled from git, so that i can easily inherit from it

3) i give up on getting this merged, and try to keep a completely standalone shepherd package in sync with what's in guix. i also give up on adding detailed instructions to the docs on how to hack on shepherd (https://issues.guix.gnu.org/54199).

i'd appreciate some guidance on how to proceed from here. i don't want to waste anyone's time further with this. if this change is not welcome in guix proper, then reject the patch and i'll try to find another way (probably option 3) to achieve my goals.

--

• attila lendvai

• PGP: 963F 5D5F 45C7 DFCD 0A39

--

“Think what you do when you run in debt; you give to another power over your liberty.”

— Benjamin Franklin (1706–1790), 'The Way to Wealth' (1758)

FTR, i've made progress, and i think i'm back to my original routine.

what i was missing is adding this to my guix .envrc:

export GUILE_LOAD_PATH=~/workspace/guix/shepherd/.guix/modules:$GUILE_LOAD_PATH

this then enables the following:

(define *parent-shepherd-package* (@ (shepherd-package) shepherd))

with this shepherd package i can once again start a `guix system vm` with all the changes in my shepherd checkout compiled in, and with a bearable turnaround time.

note that this was not suggested in the README. i'll keep an eye on updating the docs to help others getting into shepherd hacking.

thanks for your patience and help Ludo!

--

• attila lendvai

• PGP: 963F 5D5F 45C7 DFCD 0A39

--

“When a wise man points at the moon the imbecile examines the finger.”

— Confucius (551–479 BC)