Samba: add clustering functionality.

[andry-dev]

I waited for Samba 4.X to get merged to create this PR. I didn't want to interfere with the original one because it was pretty important.

This PR enables the cluster module (ctdb) and the GlusterFS VFS:

• The GlusterFS VFS (/usr/lib/samba/glusterfs_vfs.so) is needed to improve I/O performance with GlusterFS volumes. This is enabled automatically if waf can find the Gluster libraries, so to make it work it's only needed to add glusterfs-devel in the makedepends for samba and that's it.
• The ctdb module is needed to keep track of TDB across various nodes in a cluster, so that a share can be exposed as a single IP and resume operations in case of node failures. This is generally used in conjunction with Gluster, Ceph or other distributed filesystems.

Enabling both modules doesn't break existing users since these features are opt-in: for the Gluster VFS you specifically need to enable it in a share definition (see vfs_glusterfs(8)); for ctdb you need to enable and configure the daemon ctdbd.

EDIT: So it seems that glusterfs doesn't work on -musl, can I enable it only for glibc builds?

[ericonr]

EDIT: So it seems that glusterfs doesn't work on -musl, can I enable it only for glibc builds?

Yes, but I would make it a build option that gets added to build_options_default if XBPS_TARGET_LIBC is glibc.

[ahesford]

Is it appropriate for package updates to clobber everything in /etc/ctdb, or should some of the files in /etc/ctdb be marked as conf_files?

[andry-dev]

The files under /etc/ctdb, other than ctdb.conf and nodes, are scripts used for administering ctdb.

Now that I think about it, those scripts should probably go under mutable_files.

[ahesford]

Even if they are scripts, if you expect the user to modify them and you don't want to clobber them with every update, use conf_files instead of mutable_files. Files listed in mutable_files are still replaced during upgrades and removed when a package is removed, but XBPS ignores changes to the files when evaluating package integrity. Files listed in conf_files are removed or replaced if and only if their contents have not been changed by the user since installation time.

[ahesford]

Also, please incorporate ahesford@6efd1c0. I noticed some typos in the _privlib list and was able to drop a few more private shared libs. I've tested your changes (with my suggestions) against my cleanup and everything seems to build.

You should not need to modify common/shlibs when you adopt my suggestions; xbps-src warns about some unlisted libraries but, since they are intended to be private, they do not need to be described in the master list. The other private libraries are only included to satisfy interdependencies between the various samba subpackages.

[andry-dev]

Thank you for your feedback. Right now I'm not at home; I'll integrate your changes ASAP.

Just to get the last part right: I'll remove all my changes to common/shlibs, cherry-pick the commit from your repo and rebase my changes on top of that one, right?

[ahesford]

Yes, and don't forget to add ctdb-event-client to the _privlibs list, which means you won't need it in common/shlibs and you can drop the vmove usr/lib/libctdb-event-client-samba4.so in your new sub package as well.

[ahesford]

I've done a little more digging into this and have made changes in my branch to address the following concerns:

1. The ctdb package should probably be called samba-ctdb. I wondered whether ctdb served a purpose as a standalone clustered database, but as upstream seems to think its sole purpose is to be tightly coupled with Samba, the name should probably reflect that it's a subcomponent.

2. Building with GlusterFS adds a hard dependency on libglusterfs for the main samba package. The only place this appears is in the glusterfs.so VFS module, so we can put this module and its man page into a separate subpackage that will allow people to avoid the dependency without requiring a custom build.

3. After review, I don't think conf_files or mutable_files are appropriate for contents of /etc/ctdb. The functions file seems to be sourced from a lot of script not intended to be edited by users (specifically, those in /usr/share) and probably should be considered non-editable. The events contents are symlinks, which don't work properly conf_files. I think the best option we have for these files is noextract rules if users want to override the default set of event scripts.

4. Some executables in /usr/bin related to CTDB were still left behind in the main samba package.

Please take a look at commit ahesford/void-packages@d700385 and, if you have no objections, I'll merge that one.

[andry-dev]

I looked at your commit and it seems fine to me. You can merge that one and close this PR.

Thank you for your time and patience!