add discussed options for scripting support

autoinstallation/README.md

@@ -154,6 +154,131 @@ set -ex
 You might want to have a look to [Agama's default script for inspiration](./scripts/auto.sh). Such a
 script comes into action when you provide a profile.
 
+### Custom Scripts Support
+
+The goal of this section is to document examples and use cases for additional scripting support in agama autoinstall.
+
+#### Changes Before Installation
+
+##### Activation of Hardware
+
+In some cases it is necessary to manually activate tricky devices before the installation starts. Examples are two network cards, one for external and one for internal network.
+
+```sh
+set -ex
+
+/usr/bin/agama profile download ftp://my.server/tricky_hardware_setup.sh
+sh tricky_hardware_setup.sh
+/usr/bin/agama config set software.product=Tumbleweed
+/usr/bin/agama config set user.userName=joe user.password=doe
+/usr/bin/agama install
+```
+
+##### Modify the installation profile
+
+
+For various reasons, jsonnet may not be able to handle all of the profile changes that users may wish to make.
+
+
+```
+set -ex
+
+
+/usr/bin/agama profile download ftp://my.server/profile.json
+
+# modify profile.json here
+
+/usr/bin/agama profile validate profile.json
+/usr/bin/agama config load profile.json
+
+/usr/bin/agama install
+
+```
+
+#### After Partitioning
+
+Note: not supported now ( params to install is not implemented yet )
+
+##### Partitioning Changes
+
+Sometimes there is a tricky partitioning that needs to be modified after partitioning and before installing RPMs, such as changing fstab and mounting an additional partition.
+
+
+```sh
+set -ex
+
+/usr/bin/agama config set software.product=Tumbleweed
+
+/usr/bin/agama config set user.userName=joe user.password=doe
+
+/usr/bin/agama install --until partitioning # install till the partitioning step
+
+# Place for specific modifications of /dev
+
+/usr/bin/agama install # do the rest of the installation
+```
+
+#### After Deployment
+
+Note: not supported now ( params to install is not implemented yet )
+
+##### Setup Security
+
+
+If there is a need to modify the system before rebooting, e.g. to install mandatory security software for internal network, then it must be modified before umount.
+
+
+``` sh
+
+set -ex
+
+/usr/bin/agama profile download ftp://my.server/velociraptor.config
+
+/usr/bin/agama config set software.product=Tumbleweed
+
+/usr/bin/agama config set user.userName=joe user.password=doe
+
+/usr/bin/agama install --until deploy # do partitioning, rpm installation and configuration step
+
+# Example enablement of velociraptor
+
+zypper --root /mnt install velociraptor-client
+
+mkdir -p /mnt/etc/velociraptor
+cp velociraptor.config /mnt/etc/velociraptor/client.config
+
+systemctl --root /mnt enable velociraptor-client
+
+/usr/bin/agama install # do the rest of the installation - basically unmount and copy logs
+
+```
+
+##### Tune Kernel
+
+Another type of changes are changes that are mandatory for successful reboot like some kernel tuning or adding some remote storage that have to be mounted during boot.
+
+``` sh
+
+set -ex
+
+
+/usr/bin/agama config set software.product=Tumbleweed
+
+/usr/bin/agama config set user.userName=joe user.password=doe
+
+/usr/bin/agama install --until deploy # do partitioning, rpm installation and configuration step
+
+# Do custom modification to /mnt including call to dracut
+
+/usr/bin/agama install # do the rest of the installation - basically unmount and copy logs
+
+```
+
+#### After Reboot
+
+Users are just to do a lot of stuff using post install scripts in autoyast e.g. to call zypper with various modifications, modify configuration files or manipulate with systemd services. It is done after initial reboot.
+If that is the case then agama will just delegate it to any other tool user prefers for initial configuration like ignition/combustion.
+
 ## Starting the auto-installation
 
 The auto-installation is started by passing `agama.auto=<url>` on the kernel's command line. If you