Re: do_adjust_git in dpkg-base.bbclass not working for gitsm fetcher

[Henning Schild <henning.schild@siemens.com>]

Am Tue, 1 Dec 2020 12:41:08 +0100
schrieb "[ext] Jan Kiszka" <jan.kiszka@siemens.com>:

> On 01.12.20 11:41, [ext] Raphael Lisicki wrote:
> > Hi,
> > 
> > the function do_adjust_git does not work if the fetcher has been
> > set to "gitsm" which is required if the project contains git
> > submodules.
> > 
> > See
> > https://github.com/siemens/isar/blob/master/meta/classes/dpkg-base.bbclass#L26
> > 
> > 
> > This will cause the .git/objects/info/alternates remain unmodified,
> > which in turn breaks git from inside the buildchroot.  
> 
> From
> https://www.yoctoproject.org/docs/latest/bitbake-user-manual/bitbake-user-manual.html#gitsm-fetcher:
> 
> "The Git Submodules fetcher is not a complete fetcher implementation.
> The fetcher has known issues where it does not use the normal source
> mirroring infrastructure properly. [...]"
> 
> For that reason already, I would strongly discourage the use of this
> fetcher. And that's why it was never tested with Isar (to my best
> knowledge).

I have seen people use git submodules in isar recipes. But they are
hairy indeed. A big issue is whether those submodules are absolute or
relative to their main repo. Relative is your best bet, absolute will
break authentication since you might find yourself wanting to clone with
ssh and gitsm contains absolute https links.

If you control that main repo, you might want to switch to relative ...
if you can. Doing that breaks the "forking workflow" ... now every
contributor needs to fork all, or switch to absolute before working.

The worst case would be nested submodules ...

I found it best to switch over to repeating the submodule stuff in the
recipe, naming all modules with their shas and where they should be
cloned. Hard to maintain ... but you can write helper scripts writing
".inc" files containing the bits and using a clone with initialized
modules as input.

SRC_URI = "gitsm://foo.git;destsuffix=${P}"
SRCREV = "0815"

becomes

SRC_URI = "git://foo.git;destsuffix=${P};name=main
SRCREV_main = "0815"
SRC_URI += "git://bar.git;destsuffix=${P}/modules/bar;name=module1
SRC_URI += "git://baz.git;destsuffix=${P}/mod/baz;name=module2
SRCREV_module1 = "1234"
SRCREV_module2 = "abcd"

Those last 4 lines can be generated from ".gitmodules" and "git ls-tree
<main-repo-sha> <sm-path>" and stored in an include.

Henning

> In general, git submodules are hairy. And specifically in the context
> of distro (like Debian), their presence indicate that you rather want
> them as "Build-Depends" and properly packaged.
> 
> Jan
>