doc: describe usage of ansible-galaxy for installing required role dependencies

README.md

@@ -13,17 +13,16 @@ To deploy this role to a managed host, the following software must be installed
 * Python3
 * SSHd
 
-It is recommended to use this role with Red Hat Enterprise Linux VMs as prepared by the "ansible_lza_create_rhel_iso" and "ansible_lza_bootstrap_rhel_server" roles.
-
-## Quick start
-
+Other roles required by this role can be easily installed using `ansible-galaxy` if necessary. As the roles reside in SLUB's local Git server instance, you might need a password for certain repositories despite most of them being publicly available. This command will install the required roles in the correct location so they are found in the search path:
 ```
-	ansible-playbook site.yml [-i <INVENTORY_FILE>] [--limit <HOSTNAME>] [-u <USERNAME>] [-b]
+	ansible-galaxy install -r requirements.yml -p ../
 ```
 
-## General Ansible usage
+It is recommended to use this role with Red Hat Enterprise Linux VMs as prepared by the "ansible_lza_create_rhel_iso" and "ansible_lza_bootstrap_rhel_server" roles.
+
+## Quick start
 
-Most options already have sensible defaults in `ansible.cfg`. However, you can override these defaults using CLI options/flags if you want to.
+Most options already have sensible defaults in `ansible.cfg`. However, you can override these defaults using CLI options/flags if you want to. The flags can be combined if necessary, and most of them have long versions as well. Get more information using `ansible-playbook --help`.
 
 To simply run the playbook, just call the `site.yml` playbook like this:
 ```
@@ -61,8 +60,6 @@ You can then run only certain tagged tasks by using the `--tags` option:
 	ansible-playbook site.yml --tags=tag1,tag2,...,tagN
 ```
 
-For more help with ansible-playbook, use the `--help` flag.
-
 ## Testing the role
 
 Tests have been implemented using the Molecule framework. The details on using the test suite are described below `molecule/`.

requirements.yml

+---
+# https://docs.ansible.com/ansible/latest/galaxy/user_guide.html#installing-multiple-roles-from-a-file
+- src: git+https://git.slub-dresden.de/slub-referat-2-3/ansible_vaults.git
+  scm: git
+- src: git+https://git.slub-dresden.de/digital-preservation/ansible_lza_install_common.git
+  scm: git
+- src: git+https://git.slub-dresden.de/digital-preservation/ansible_lza_server_hardening.git
+  scm: git
+#- src: git+
+#  scm: git