gnocchi-indexer-sqlalchemy not packaged

What is the output of:

lsb_release -a; uname -a; cat -n /etc/apt/sources.list

Thanks

No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04.3 LTS
Release: 16.04
Codename: xenial
Linux unassigned 4.4.0-104-generic #127-Ubuntu SMP Mon Dec 11 12:16:42 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
     1 # deb http://archive.ubuntu.com/ubuntu xenial main restricted
     2
     3 # deb http://archive.ubuntu.com/ubuntu xenial-updates main restricted
     4 # deb http://security.ubuntu.com/ubuntu xenial-security main restricted
     5
     6 # See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
     7 # newer versions of the distribution.
     8 deb http://archive.ubuntu.com/ubuntu xenial main restricted
     9 # deb-src http://archive.ubuntu.com/ubuntu xenial main restricted
    10
    11 ## Major bug fix updates produced after the final release of the
    12 ## distribution.
    13 deb http://archive.ubuntu.com/ubuntu xenial-updates main restricted
    14 # deb-src http://archive.ubuntu.com/ubuntu xenial-updates main restricted
    15
    16 ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
    17 ## team. Also, please note that software in universe WILL NOT receive any
    18 ## review or updates from the Ubuntu security team.
    19 deb http://archive.ubuntu.com/ubuntu xenial universe
    20 # deb-src http://archive.ubuntu.com/ubuntu xenial universe
    21 deb http://archive.ubuntu.com/ubuntu xenial-updates universe
    22 # deb-src http://archive.ubuntu.com/ubuntu xenial-updates universe
    23
    24 ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
    25 ## team, and may not be under a free licence. Please satisfy yourself as to
    26 ## your rights to use the software. Also, please note that software in
    27 ## multiverse WILL NOT receive any review or updates from the Ubuntu
    28 ## security team.
    29 deb http://archive.ubuntu.com/ubuntu xenial multiverse
    30 # deb-src http://archive.ubuntu.com/ubuntu xenial multiverse
    31 deb http://archive.ubuntu.com/ubuntu xenial-updates multiverse
    32 # deb-src http://archive.ubuntu.com/ubuntu xenial-updates multiverse
    33
    34 ## N.B. software from this repository may not have been tested as
    35 ## extensively as that contained in the main release, although it includes
    36 ## newer versions of some applications which may provide useful features.
    37 ## Also, please note that software in backports WILL NOT receive any review
    38 ## or updates from the Ubuntu security team.
    39 deb http://archive.ubuntu.com/ubuntu xenial-backports main restricted universe multiverse
    40 # deb-src http://archive.ubuntu.com/ubuntu xenial-backports main restricted universe multiverse
    41
    42 ## Uncomment the following two lines to add software from Canonical's
    43 ## 'partner' repository.
    44 ## This software is not part of Ubuntu, but is offered by Canonical and the
    45 ## respective vendors as a service to Ubuntu users.
    46 # deb http://archive.canonical.com/ubuntu xenial partner
    47 # deb-src http://archive.canonical.com/ubuntu xenial partner
    48
    49 deb http://security.ubuntu.com/ubuntu xenial-security main restricted
    50 # deb-src http://security.ubuntu.com/ubuntu xenial-security main restricted
    51 deb http://security.ubuntu.com/ubuntu xenial-security universe
    52 # deb-src http://security.ubuntu.com/ubuntu xenial-security universe
    53 deb http://security.ubuntu.com/ubuntu xenial-security multiverse
    54 # deb-src http://security.ubuntu.com/ubuntu xenial-security multiverse

What is the "Queens Cloud Archive" please?

https://wiki.ubuntu.com/OpenStack/CloudArchive
sudo add-apt-repository cloud-archive:queens

I suggest you contact the PPA maintainer. They will be able to advise you

Thanks Manfred Hampl, that solved my question.