Precedence: list
MIME-Version: 1.0
In-Reply-To: <CA+T2pCGeMe+LgApEwUju6NL8FCSAPxY7bPCKDHw5Pj3FXZvqCA@mail.gmail.com>
References: <5ad90a46-8c78-ebdd-e022-a94fe7937805@bitmessage.ch> <CA+T2pCGeMe+LgApEwUju6NL8FCSAPxY7bPCKDHw5Pj3FXZvqCA@mail.gmail.com>
From: William Pitcock <nenolod@dereferenced.org>
Date: Tue, 15 May 2018 23:13:02 -0500
Message-ID: <CA+T2pCEdamivZ8J1JL7L2p8abgboP6MBdyDjMbdcOs53c2=nxg@mail.gmail.com>
Subject: Re: [alpine-devel] apk and libraries that optionally replace others
To: Oliver Smith <ollieparanoid@bitmessage.ch>
Cc: alpine-dev <alpine-devel@lists.alpinelinux.org>
Content-Type: text/plain; charset="UTF-8"

Hello,

On Tue, May 15, 2018 at 11:08 PM, William Pitcock
<nenolod@dereferenced.org> wrote:
> Hello,
>
> On Tue, May 15, 2018 at 3:57 PM, Oliver Smith
> <ollieparanoid@bitmessage.ch> wrote:
>> Hey folks,
>>
>> in Alpine based postmarketOS we have hit the following use case quite a
>> few times by now, and we're wondering how to solve it properly:
>> Packaging "testlib-b" as a _optional_ replacement for "testlib-a".
>>
>> Both "testlib-a" and "testlib-b" provide the same soname, which means
>> abuild will automatically make both binary packages provide
>> "so:libtestlib.so.1".
>
> By default this means that both packages will provide
> so:libtestlib.so.1 with provider_priority 0.  When provider_priority
> is 0, it means to skip automatically resolving the provider.  Provider
> selection is based on a combination of priority and overall "cost" of
> choosing that provider.  apk will prefer the highest priority provider
> with the lowest cost (dependency chain length) that can yield a
> satiable solution.
>
>> Now there is a "testapp" package, which has "testlib-a" in makedepends
>> and links against "libtestlib.so.1". Therefore abuild puts
>> "so:libtestlib.so.1" in the depends of "testapp". What we would like to
>> achieve is, that whenever installing "testapp", it pulls in "testlib-a".
>> But when "testlib-b" is already installed, it uses "testlib-b" instead
>> of "testlib-a".
>
> testlib-b (libdrm) should have provider_priority 1, testlib-a
> (libdrm-grate) should have provider_priority greater than 1.  The
> provides field itself should be left alone.  The key is to set a
> priority on both providers, otherwise APK will treat it as a collision
> and behave as you describe.

For what it's worth, I am open to adding provider_priority=1 to
libdrm.  But it's not my package, so I prefer to hear from ncopa who
maintains it first.  Otherwise, you will need to rebuild the package.

William


---
Unsubscribe:  alpine-devel+unsubscribe@lists.alpinelinux.org
Help:         alpine-devel+help@lists.alpinelinux.org
---