I tested the execution of the new preinstall_cmd and preinstallopts in the following cases and it successfully works in all of them:

• Single preinstallopts

'preinstallopts' = 'touch A && touch B && '

• Single preinstall_cmd

'preinstall_cmd' = 'touch C && touch D'

• Both preinstallopts and preinstall_cmd

'preinstallopts' = 'touch A && touch B && '
'preinstall_cmd' = 'touch C && touch D'

@lexming Coincidentally PR easybuilders/easybuild-framework#3270 was opened today in framework that intends to cover (some of) the same ground as this, can you check if that approach would suit your needs?

@ocaisa that PR merges the folders instead of installing them in different subfolders. That will not work for bundles, at least not in a general sense, as the source code of different projects will probably have collisions.

@ocaisa I think that both options can complement each other and could be added to tarball. Maybe a variable called install_type that would accept merge or subdir as options. I'll wait to see what @Darkless012 proposes.

I might be repeating, but let me summarize what is needed by this change:

1. Don't remove install dir in tarball - on which we all agree, because this should be done by easyconfig and brings trouble to Bundles.
2. Allow changing (in some way) installdir so that conflicts will not arise.

Do you have any specific use-case other than using this in Bundle?

I needed step 1 Because I had MakeCP and Tarball. MakeCP would create installdir/bin/executable and then Tarball should copy its content (into installdir which includes bin folder) as well. Which is my need in merging folders instead of remove/copy. So there should be extra param "merge folder" which should not be default as you mentioned.
I can reverse the order of components for sure. But Tarball still shouldn't remove folder.
But as you pointed with install_in_subdir I might just have different folder with bin/executable and add it to the PATH?

I didn't thought about having multiple Tarballs in bundle, which is valid point. I like the idea of having install_in_subdir.
Just want point out that if you are already installing it into bundle, you might want to specify exact path within the installdir? Which is basically what I'm doing with MakeCp (files_to_copy).
Sure you can do mv/ln -s in postinstallcmds, where the install_in_subdir makes sence, because you will have always same name structure to copy from?

Does install_in_subdir has any other use besides Bundle?
"merge_folder" probably doesn't have since installdir should be wiped in solo Tarball installation.

List of use cases and required actions needed for each of them:

1. Installation of a single tarball

   • Wipe existing installation directory (we do not want any unexpected behaviour caused by leftovers)
   • Unpack and copy tarball

2. Installation of a multiple tarballs, where one is the main package and the other are addons that have to be decompressed in paths below the main one

   • Extract sources of main package using default settings
   • Extract sources of addon tarballs in paths under main package with specific extract_cmd (see for instance {phys}[foss/2019b] dftd3-lib v0.9, DFTB+ v19.1 w/ Python 2.7.16 easybuild-easyconfigs#10351)
   • tarball easyblock will do a single copy of everything to installation directory.

3. Installation of multiple tarballs, where all of them have to be merged in a common installation directory. Useful for Bundles were tarball easyblock comes after other easyblocks that have already populated the installation directory.

   • Installation directory will be already wiped and populated by previous easyblock
   • Copy files to installation directory without wipe and enabling dirs_exist_ok

4. Installation of multiple tarballs, where each of them is independent from the others and live in their own subdirectory. Useful for Bundles with multiple tarball easyblocks.

   • Wipe installation sub-directory
   • Unpack and copy tarball to specific sub-directory

Cases 1 and 2 are already supported. The default behaviour of tarball should not change to avoid breaking existing easyconfigs.
Support for case 3 and 4 will be added by this PR. Since these two options are exclusive, I propose to have a single option that can be set to one or the other.

@Darkless012 @ocaisa I have added the option install_type to handle default installations and also the options of merging the contents of the tarball or extracting them in their own sub-directory. Please test it and let me know your thoughts.

I've tested it combining several tarball components in a single bundle with various combinations of options (None, merge, subdir) and all worked well on my end.
With this PR all four use cases listed in #1989 (comment) should be covered.

@lexming PR looks good, can you share that test case (here or in a gist) just so I repeat the tests for myself?

@ocaisa I put the dummy easyconfig to test this PR in https://gist.github.com/lexming/3477ca1390b1965affb6338efc5f1dd7
It's just a stripped down version of my PR for Alpha (easybuilders/easybuild-easyconfigs#9994) with the updated settings from this PR for tarball.
The version I'm sharing uses subdir and should fulfil the sanity checks. The python package has its own lib folder and pyinclude and alpha are in their own folder. You can change the settings for install_type to merge or None and check the different results.