Re: [PATCH 1/3] tools/router: use socket activation

Alyssa Ross
2025-12-09T11:02:09Z

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Demi Marie Obenour <demiobenour@gmail.com> writes:

> On 12/9/25 05:55, Alyssa Ross wrote:
>> Demi Marie Obenour <demiobenour@gmail.com> writes:
>>
>>> On 12/8/25 19:38, Alyssa Ross wrote:
>>>> This means we can use readiness notification to wait until the sockets
>>>> are created without having to add special functionality for that to
>>>> the router program, and also means we can do extra system-specific
>>>> setup to the sockets, like changing their owners, outside of the
>>>> router.
>>>>
>>>> Since the socket paths were the only arguments taken by the router,
>>>> this also lets us drop the clap dependency entirely.
>>>
>>> I strongly recommend open-coding the file descriptor stuff instead
>>> of using a third-party library for it. It's just a two calls to
>>> getsockopt() (SO_DOMAIN and SO_TYPE) per socket, and listenfd pulls
>>> in wasm-bindgen and js-sys!
>>
>> It pulls in wasm-bindgen and js-sys if you're building for those
>> platforms, which we are not. An inert mention in Cargo.lock is not a
>> problem. The only dependency of listenfd in our context (checked via
>> cargo tree) is on libc, which is already a dependency of tokio.
>>
>> I've implemented systemd socket activation in Rust before, and it's not
>> at all nice, even with libsystemd. listenfd adds 295 extra lines of
>> code in total. I think that's worth it.
>
> Ah, I didn't mean to actually implement the whole thing, but rather
> to open-code the specific case used here.
>
> If listenfd is a very popular crate, I'd go with it. Otherwise,
> I'd be too concerned about supply-chain risk. On the other hand,
> I might be too used to having to use Fedora and Debian packages for
> my Rust dependencies.

"#28 in Unix APIs", ahead of landlock and just behind libseccomp.

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