[Tarantool-patches] [PATCH v2] build: don't start example instance in postinstall

[Alexander Turenko]

LGTM.

Pushed to master and 2.4. CCed Kirill.

WBR, Alexander Turenko.

On Tue, Jun 09, 2020 at 02:40:36PM +0300, Olga Arkhangelskaia wrote:
> After tarantool installation on Debian/Ubuntu from repo, example instance
> was automatically started on 3301 port. At the same time example instance
> on RHEL/CentOS is started manually. Patch does the same for Debian/Ubuntu.

Nit: Over 72 symbols.

> 
> If tarantool is installed not for the first time,
> do "apt-get purge tarantool-common" before installation to get rid of link in
> /etc/tarantool/instances.enabled.

Note: There is no such sentence in the commit on the branch. However the
commit is okay without it too, so I would not bother much.

> 
> Closes #4507
> ---
> Brabch: gh-4507-disable-start-example-instance-full-ci

I rebased and force-pushed it to verify again (just in case).

https://gitlab.com/tarantool/tarantool/-/pipelines/154589256

release_asan_clang8 fail is the same as on master, so is not related to
the patch. Other jobs are passed.

Removed the branch.

> @ChangeLog:
> - disabled start of example instance after installing from Debian/Ubuntu
>   repo.

Nit: Don't forget to include (gh-xxxx) at the end.

> If there is no installed version of tarantool-common, one should do
> "apt-get install tarantool-common".

'tarantool' package depends on 'tarantool-common', so it is not
necessary. Moreover, when 'tarantool-common' is installed as the
dependency for 'tarantool' package it is marked as 'auto' package and
will be removed by `apt-get autoremove` (or `debfoster`) after removal
of 'tarantool' package. See [1] for more information about autimatic
dependencies.

[1]: https://books.google.com/books?id=xmfTCgAAQBAJ&pg=PA115

> If tarantool-common was installed before, and even removed,
> installation or upgrade won't take effect, because the link to example
> instance still present in /etc/tarantool/instances.enabled.
> Do following steps to get rid from example instance starting every time:
> "apt-get purge tarantool-common"
> "apt-get install tarantool-common"

In order to avoid explicit (re)installation of tarantool-common I would
suggest to stop the instance and remove the symlink manually:

 | # systemctl stop tarantool at example
 | # rm /etc/tarantool/instances.enabled/example.lua

Having everything said above in the mind I added the following entry to
the release notes:

@ChangeLog

- Don't start 'example' instance after installing tarantool (gh-4507).

  Before this release tarantool package for Debian and Ubuntu
  automatically enable and start 'example' instance, which listens on
  the TCP port 3301. Starting from this release the instance file is
  installed to /etc/tarantool/instances.available/example.lua, but is
  not enabled by default and not started anymore. One may perform the
  following actions to enable and start it:

  ```
  # ln -s /etc/tarantool/instances.available/example.lua \
        /etc/tarantool/instances.enabled/example.lua
  # systemctl start tarantool at example
  ```

  Existing configuration will not be updated automatically at package
  update, so manual actions are required to stop and disable the
  instance (if it is not needed, of course):

  ```
  # systemctl stop tarantool at example
  # rm /etc/tarantool/instances.enabled/example.lua
  ```