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. These instructions are for
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 this example, TPA installs its own list of ``default_packages`` , the
packages listed under ``packages.common`` on every instance, and the
remaining distribution-specific packages based on the distribution the
instance is running. If any of these packages isn’t available, the
deployment fails.

Don’t list any packages that depend on Postgres. Use :ref:`extra_postgres_packages <Installing Postgres-related packages>` 

instead.

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

You can specify a list of ``optional_packages`` that can be installed.
They will be installed if they’re 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`` to remove if they’re
installed.

.. code:: yaml

   unwanted_packages:
     common:
       - badpkg1
     Ubuntu:
       - badpkg2