This directory is empty on purpose in git. Content in this folder is populated packaging time (see package.sh/package.conf) and can be modified if needed also on target server where package is installed.
All application related configuration variables are defined in the application_configuration.yml file in this folder. The name of the configuration file can be altered but it must be passed to ansible run as command line variable file nevertheless.
Example:
./run_playbook.sh application.yml -i application/hosts.yml -e @application/application_configuration.yml
Application helm charts must be available on infra node before application playbook is executed. That folder on infra node is specified within app_helm_charts_infra_directory variable.
There is a good default value for this variable and if not changed, installer will handle Helm charts transfer from packaging up to the target infra server.
Installer supports optional custom pre and post install roles. Custom roles' code folders are placed into this directory at packaging time and names of those folders shall be configured in application_configuration.yml with variable application_pre_install_role and application_post_install_role. Note that these directory names must correspond to those configured in APP_CONFIGURATION inside package.conf during package build time.
Example:
application_pre_install_role: "my-pre-install-role"
Ansible inventory file is least application specific but in practice example inventory file in git ansible/inventory/hosts.yml cannot be directly used anyway and at least ip addresses need to be changed according to target servers after installer installation and before starting installer execution.
So it's better to place also hosts.yml to this application directory and edit it here. That can be done either at packaging time same way as application_configuration.yml or after package has been installed to server where ansible process are run just before lauching any playbooks.