On Fri, Apr 15, 2016 at 05:19:04PM +0100, Stephen C. Tweedie wrote:
Hi,
On Thu, 2016-04-14 at 18:35 +0200, Petr Šabata wrote:
>
the first draft of the module metadata format is now available
> for you to comment on. We've decided to go with YAML so it
> should be fairly readable. You can view the latest version here:
>
>
https://pagure.io/fm-metadata/blob/master/f/metadata.yaml
>
> What is is:
> The file defines basic properties of the module such as its
> name, version, description, licenses, references to upstream
> documentation or its content. Currently only RPM content
> is supported but this can be easily extended in the future.
> The metadata file is meant as both input and output of the
> module build process (don't confuse it with package build
> process), with various tools adding various new data to it,
> such as vendor and buildsystem identifiers, timestamp of the
> build, autogenerated lists of licenses or whatever you can
> think of (well, maybe not whatever but close). The output is
> then placed in the generated repository, container image or
> any other module deliverable and can be processed by tools and
> services consuming and delivering modules.
>
> What is isn't:
> It's not a SPEC file. It doesn't say how to build individual
> packages. And it's not a simple comps group either. It can
> and does provide lots more additional data.
>
> It's not perfect and it's constantly evolving. Please, do
> comment, ask questions and suggest improvements.
How easy is it to modify and change field definitions around? I see
you've got a version identified for the format already --- good, that's
definitely something we want here.
Should be simple. We just bump the version number if it's a
breaking change. I also maintain a small library that should
provide an abstract API for handling this.
One thing I think we need is a bit more detail in the module
dependencies. We don't need them all for the initial task of building
a module and testing its repoclosure; but I think we may well have a
need for (for example)
* Package build deps: what other modules you need to compile packages
in this module. (This basically defines the build root for the
module, and we want to be able to make sure we're using a consistent
build root with consistent compiler versions etc. for all the
packages in a module.)
A buildrequires field was present in an earlier draft but I
removed it as it wasn't (and still isn't) entirely clear what
it actually means to build a module. I expect to put it back
once this is more clear.
* Runtime deps: what other modules need to be enabled by the user
at
runtime to use this module. Eg. library dependencies, CLI tool
requirements.
You can define versioned module runtime dependencies in the
requires field.
* -Devel deps: what other modules need to be enabled by the user to
build applications against this module.
Currently -devel (and other) subpackages are included if the
fulltree option is set to true. This is the default.
We could also expand on the module ID a bit. Many packaging systems
use a hierarchical naming scheme --- eg. instead of name: foo, name
might be "foo.fedora.org". A maintainer name and reference download
URL/homepage could also be useful here.
This is an interesting idea. Noted.
But the main place I'd like to see expanded is the package list
itself.
In addition to the list of packages included, I think we need:
What is the function of the package? It may be:
* A runtime component which is part of the official API of the module.
We can do things like verify ABI compatibility on these components
on updates if we want.
* A runtime component which is an internal implementation-detail only
(similar to the distinction between unstable, internal and stable,
external symbols in a library.) A user should know not to rely on
these components remaining the same on module updates.
We should also record which externally-usable package needs this
internal dependency in this case.
At the moment we list the "main" components of the module.
Other packages, such as the related subpackages, source RPMS
or debuginfos are automagically included if the fulltree option
is enabled (again, defaults to true).
Dependencies of the listed components that aren't provided by
any of the required modules are also included in the module if
the dependencies option is enabled (also defaults to true).
I would say the listed components could be considered the
"official API" and the bundled (an ugly word, I know)
dependencies would be the internal implementation detail.
You could also place comments in the (source control tracked)
YAML file for extra information. Of course these wouldn't
be normally visible to any processing tools but I don't think
that's important. Correct me if I'm wrong.
* A -devel package: never needed at runtime; only used if a
developer
is building an application against the module.
These are available via the fulltree feature, without the need
of listing them explicitly.
* Debuginfo. We could choose to keep debuginfo in the module
itself,
marked this way; or we could keep separate debuginfo lookasides or
separate debuginfo modules. Not sure which way we'll eventually go,
but it would be useful to at least be able to mark packages which
are included only for runtime debugging.
The same as above. We might split fulltree into two or more
options later, if required.
For long-term distro maintenance, it will be *hugely* helpful to be
able to look at content and say "why do we have this package? Does
anyone actually need it, or is it only there to satisfy some dependency
for an application that was added years ago and might not even need it
any longer?"
Making the distinction between external and internal functionality, and
recording explicitly what needs the internal pieces, will really help
that sort of long-term maintenance, making it much easier to see when
dependencies are no longer needed.
If it's a bundled dependency, an implementation detail, it would
be remove automatically the next time you build the module --
in case none of your main components needs it anymore.
Again, extra info could be added as comments.
Or do you think it'd be useful to have these as separate fields?
P
> Thanks,
> P
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