Re: Include non-RPM content in buildroot

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Hi,

thank you all for your input! I have few notes:

Review process:
I don't think that the review process is a problem. It is independent of the file format we use. I mean we can have regular review process and store the package in a tarball as well as we do it with RPM.

Go package management:
I know that Go has a package management now, but the question is if upstream communities are going to adopt it.

Storage requirements:
Regarding the amount of packages, of course I don't want to clone the whole registry, I just want to do the same we already do, but without RPM.

-compat packages for Rust:
I, personally, don't like the proposed solution because it requires a lot of manual work and my goal is to remove as much manual work as possible.

mock:
I am aware that we don't have Internet access during RPM build, but as I said above, we can do the same with tarball and RPM.

Thanks for this email thread I also had few discussions off-line and it seems to me that there is a certain shift in the way people want to distribute their software. More specifically I could see more people focus on shipping their software in containers and trying to avoid RPM completely.

Regards,
Martin

On 2/21/20 3:57 PM, Martin Sehnoutka wrote:
Hi,

before I write the proposal itself I just want to stress the fact that it isn’t my intention to change the current packaging workflow and definitely not the user experience. Also if you have C or Python packages it would not affect your work at all (I’m not familiar with all interpreted languages in Fedora, but I guess it is similar to Python and therefore it is not affected by the problems I am going to describe).


First of all, let me describe the problem I see in our Fedora ecosystem with relation to Go and Rust language ecosystems. More specifically in the relation between RPM buildroot and packages in these ecosystems. Both of these languages follow the idea that packages should be small and only have a limited set of features. Developers then use a lot of these packages to write the final executable that is meant for end-users [1]. Also both of these languages use static linking of the final binaries meaning that Fedora users don’t install RPM packages of these libraries as they are already baked inside of the binary [2].


The 1st problem is that if we want to build RPMs of the final executables the way we do now, we need to package all these small libraries into RPM even though they are just build dependencies and users never install RPMs of these libraries. Many of these RPMs are automatically generated from the upstream packages meaning that we don’t do anything except for unpacking the upstream package (e.g. plain tarball in case of crates.io)  and then we package the same into RPM. This process is unfortunately not fully automated and therefore requires a certain amount of human effort.


To sum up the previous paragraph, I don’t think it is necessary to repackage upstream tarball into a downstream RPM.


The 2nd problem is present only in the Rust ecosystem (as far as my knowledge goes). Cargo, the official package manager for Rust, can handle the scenario where an executable depends on a single library in two different versions [3]. Dnf, on the other hand, will not install two versions of the same RPM package. What we do now is, that we patch the affected executables and libraries to only use the newest versions everywhere. This is again an additional maintenance cost and we create differences from upstream, because these patches are not necessarily merged. See this as an example: https://src.fedoraproject.org/rpms/rust-bstr/blob/master/f/rust-bstr.spec#_17
https://github.com/BurntSushi/bstr/pull/23


To sum up the 2nd problem: we are using dnf instead of the upstream package manager to install dependencies. These two approaches can be incompatible (and they are in case of Rust).


The 3rd problem I see is that issues like this are not going away, they are only going to get worse as other ecosystems emerge. e.g. if the Swift language became popular (for Linux development) it would again have it’s own package manager and probably its own set of issues in relation to our build system. (I mention Swift specifically because it is a compiled language that have stable ABI only for std, other libraries are statically linked)


Now, I’d like to point out that Go and Rust packaging works well in Fedora due to the enormous effort of certain people and I very much admire the work they do. But on the other hand I’m afraid where the ecosystem would go without them. This is where we get to the situation in the enterprise derivatives, specifically RHEL and CentOS. Their solution to this problem is not to package all libraries separately but to bundle all libraries directly into source RPMs of each executable. So the bundling is not present only on the binary file level, but also on the source RPM level. Go went even further in this case and it is common to bundle all the dependencies as a source code directly in the upstream repository. See this repo as an example:
https://github.com/containers/libpod/tree/master/vendor


It is fair to say, that my first motivation was the current state of packaging in RHEL but I’d prefer to discuss this in Fedora first.


The proposal itself is fairly simple: Let’s stop packaging all Go and Rust libraries into RPM and install them to the buildroot in the upstream format instead.


The specific implementation is up for a discussion but I think it is logical to start by asking what features do we want from the build system? My answers are:


 * We want to know what exactly was used to build the RPM to ensure integrity. This is possible with upstream tarballs as well as with RPMs. Just store a hash of the tarball.  * There should be no maintenance cost. If we would avoid modifying the upstream package it would be the ideal case.  * It should be possible to patch the library in case of severe issues like CVEs. This is a contradiction to the previous point, but it could be solved by unpacking the upstream package into a git repository and creating a new, modified package in upstream format from it.  * It should be possible to run the build locally in exactly the same way Koji does it. This is just about exposing our “registry” of packages to the public Internet.


Finally, the implementation could be something like this:
A service like release-monitoring could monitor the upstream projects for new releases (e.g. NPM has a RSS feed). Every time there is a new release it would automatically synchronize our own Fedora-specific registry, which would in turn be accessible in buildroot. Then the RPM macros like “cargo_build” could be modified to use this registry. If we wanted to have the possibility to patch these libraries we could synchronize the upstream release into our git repository and generate packages in upstream format from it.


What do you think about the way we build RPM packages for Go and Rust? Do you see other solutions or is it ok the way it is? (Please do not suggest to “fix” the upstream communities)

Thanks for your opinions!
Martin


FAQ:
  * Does it mean you want to get rid of -devel subpackages for C libraries?

No. First of all C language does not have a single package manager and it is still common to install dependencies using the distro specific package manager. But packaging into RPM also comes with the advantage of having shared libraries so in this case it has a positive effect on the end-user experience. Rust and Go libraries on the other hand are mostly useless for end-users.


 * I prefer to install development libraries using the distro package manager instead of the upstream package manager. Why do you want to change it?

This is the case for C development, but it is different in most of the modern languages. For example we ship Python packages, but we discourage people from using them for their own development. Python developers are instead encouraged to use pip to create a virtual environment and use upstream packages. In the case of Rust, using the system libraries would be much harder than using the upstream package manager.


  * Does it mean you want to get rid of Rust packages like ripgrep?

No. The end user experience stays unchanged. Packages that we ship to Fedora users must be in RPM format, it is only the buildroot that changes.

Notes:
[1] Please don’t discuss if it is a good idea or not. This is a discussion for upstream of those languages.
[2] Again, please don’t discuss static vs. dynamic linking here.
[3] https://stephencoakley.com/2019/04/24/how-rust-solved-dependency-hell
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