[Pkg-nginx-maintainers] [Resend] [RFC] nginx packaging refactor

[Miao Wang]

Dear nginx maintainers,

I'm a user of Debian nginx packages. I'm writing to suggest a possible way to 
improve the packaging of nginx in Debian.

Currently, the nginx package is shipping several useful third-party modules. 
However, the modules are embed into the debian/modules directory and compiled
along with the nginx binary, which has three shortcomings: 1. the version number
of third party modules is forced to be the same with the nginx binary, although
they have their own version numbers, and thus it is not convenient to track
their versions. 2. An simple upgrade to any of the modules and nginx itself
would trigger a total rebuild of the entire package, and resulting the users to
upgrade all the packages. 3. Embedding too much code in debian/ directory does
not look good and is somewhat o kind of abuse.

The root cause of the problems is that nginx lacks the native ability to compile
out-of-tree modules separately. However, using all the headers and the configure
scripts in the auto/ directory, out-of-tree modules can be successfully
compiled.

Utilizing this mechanism, I created a new package called nginx-dev, containing
all the headers and scripts needed to compile a nginx module, removed all the
3rd-party modules in the nginx package, and put them in separate packages. 
Additionally, I created debhelper scripts to help the packaging of nginx
modules and improved the dn_nginx script.

The module packages have their own versions now and for those the version of
which is smaller than the current nginx, I increased the epoch. All the modules
depends on an exact upstream version, but not a certian debian revision, because
the signature in a module contains the version number and we can assure that
we won't introduce abi changes to nginx during revisioning. Thus, patching nginx
won't affect the modules and the users can upgrade only the main nginx packages.

I put the above work at https://salsa.debian.org/shankerwangmiao/nginx in the
feat-remove-mods branch, and modules also at shankerwangmiao/ngx-* in the
deb/<ver> branch. I also included the njs module, which I'd like it to be an
example for a complex module.

It would be grateful if you have any comments on my work.

Cheers,

Miao Wang