Title: #255: Use default configuration with missing sssd.conf
The problem I was considering was that before (in current master), if
you compile sssd with --disable-files-domain (which is the default), then you can't
start sssd without a config file.
And it is a bug because this options has nothing to do with missing configuration file.
--enable-files-domain If this feature is enabled, then SSSD always enables
a domain with id_provider=files even if the domain
is not specified in the config file [default=no]
it just changes default value of the option `enable_files_domain` from `false` to `true`
When this option is enabled, SSSD prepends an implicit domain with
“id_provider=files” before any explicitly configured domains.
This patch changes this behaviour to start the implicit domain with
no config file, so what the option now does is adding the additional files domain even if
explicit domains are configured, right?
`prepends an implicit domain` has nothing to do missing `sssd.conf` from semantical POV.
They are two different things. It is just an implementation detail that
`enable_files_domain = true`.
The same could be achieved with different `SSSD_FALLBACK_CONFIG_LDIF` but
`SSSD_FALLBACK_CONFIG_LDIF` would be much bigger.
I'm not sure I would like that in RHEL. Although typically in
RHEL, the order of nsswitch modules is "files sss", so for files users, sss
wouldn't be typically reached at all..which might make the change OK..
There is not a huge functional difference between this PR and version which was introduced
a year ago 59744cff6edb106ae799b2321cb8731edadf409a. And As I already mention
59744cff6edb106ae799b2321cb8731edadf409a was reverted in RHEL due to other reasons and not
because missing sssd.conf caused problems
See the full comment at https://github.com/SSSD/sssd/pull/255#issuecomment-299459227