Installing packages
===================

TPA installs a batch of non-Postgres-related packages early during the
deployment, then all Postgres-related packages together, and then
packages for optional components separately. This page is about
installing packages like sysstat or strace, which have no dependency on
Postgres packages.

You can add entries to ``packages`` under ``cluster_vars`` or a
particular instance’s ``vars`` in config.yml:

.. code:: yaml

   cluster_vars:
     packages:
       common:
         - pkg1
         - pkg2
       Debian:
         - debpkg1
       RedHat:
         - rhpkg1
         - rhpkg2
       Ubuntu:
         - ubpkg1
       SLES:
         - slespkg1

In the example above, TPA will install its own list of
``default_packages`` and the packages listed under ``packages.common``
on every instance, and the remaining distribution-specific packages
based on which distribution the instance is running. If any of these
packages is not available, the deployment will fail.

Don’t list any packages that depend on Postgres; use :ref:`Installing Postgres-related packages <Installing Postgres-related packages>` 

instead.

Optional packages
-----------------

You can specify a list of ``optional_packages`` to install. They will be
installed if they are available, and ignored otherwise. As with the
other settings, the ``common`` entries apply to every instance, whereas
any other lists apply only to instances running the relevant
distribution.

.. code:: yaml

   optional_packages:
     common:
       - pkg1
       - pkg2
     Debian:
       - debpkg4

Removing packages
-----------------

You can specify a list of ``unwanted_packages`` that should be removed
if they are installed.

.. code:: yaml

   unwanted_packages:
     common:
       - badpkg1
     Ubuntu:
       - badpkg2