spksrc: Fully use DSM7 var directory

[th0ma7]

Description

Motivation: Follow-up to to both #4579 and #4797 with focus only on var. This now uses previously merged PR such as:

• (installer.dsm7: Use rsync to synchronize var directory #4997) Usage of rsync to migrate target/var to var in spksrc.service.installer.dsm7
• (installer.dsm7: Use rsync to synchronize var directory #4997) Add a functionality that allows generating .new suffix new files when previous ones already exist. User can then refer to them and adapt their own configuration as needed.

Current framework simply move files from target/var to target/../var at package installation/upgrade time. While it's probably fine for most use-cases, this doesn't adapt all configuration files at build time using the "real" end-state path and most importantly the application isn't "aware" by default of the expected var directory path.

Solving this require using localstatedir option at configuration time. Doing so enforces the application to have an awareness and use by default the new DSM7 var directory and thus, installs files at the proper location and adjust paths in configurations at build time. Not doing so leaves a bit of unknown on actual application state & behavior.

This PR aims at solving the current limitations by doing the following on top of rsync work (#4997):

1. enforcing the usage of localstatedir for DSM7 builds. At package generation time, files installed under <workdir>/install/var/package/<package>/var are now being handled in order to be packaged and installed properly.

Details

This new implementation is a major step above previous attempt as it:

1. requires NO changes at all in any packages.
2. is key to demonstrate feasibility to also migrate etc in a later work

Checklist

• Build rule all-supported completed successfully
• New installation of package completed successfully
• Package upgrade completed successfully (Manually install the package again)
• Package functionality was tested
• Any needed documentation is updated/created

Type of change

• Bug fix
• New Package
• Package update
• Includes small framework changes
• This change requires a documentation update (e.g. Wiki)

[Safihre]

I tried to review, since I know you put a lot of work in it, but I am not fully understanding (even after reading the previous PR) what this change will do?
Maybe you could explain it again shortly?

[th0ma7]

Thnx @Safihre for looking into it. It is now ready for review (you where a few minutes to early). I've added a much better description + a diagram that explains it hopefully well.

[Safihre]

Based on your diagram, it looks good. All changes seem logical.
But @hgy59 or someone else is more an expert.

[th0ma7]

@SynoCommunity/developers Friendly reminder for reviews. Unless there is opposition to this PR I'll look into merging in the coming days.

[hgy59]

I have a package under development (urbackup) where the cross packages create config files in the var folder. PLIST contains entries like rsc:var/urbackup/dataplan_db.txt.

After rebase to include this PR, DSM 7 packages cannot be created anymore.

• The install folder for DSM 7 does not contain the {packagename}/target/var but the {packagename}/var with the required config data.
• The staging folder for DSM 7 is empty, and does not contain the directory structure of {packagename}/var in the install folder, so there is an error:

  ===>  [DSM7+] Copy & merge var and target/var to /spksrc/spk/urbackup/work-x64-7.0/staging/var
  tar: Cowardly refusing to create an empty archive
  

@th0ma7 any idea how to handle this?

[th0ma7]

@hgy59 can you point me to your development branch i'll look into it probably tomorrow.

[hgy59]

@th0ma7 the copy and merge of different var folders needs two command lines, as tar must be executed within each var folder separately.

[hgy59]

The following existing cross packages have var folders in PLIST

• domoticz
• ejabberd
• mutt
• rsnapshot
• saltgui (spk: salt-master)
• zap2epg (spk: tvheadend)

@th0ma7 shall I create a dedicated PR to merge this fix to master?

[th0ma7]

Yes please do @hgy59 , I'll have a second look at it as well.

EDIT: I can't reproduce your issue... I tried with rsnapshot and mutt and all is good with the current code.