README: Add more instructions

Signed-off-by: gigadjo <[email protected]>

README.md

@@ -3,7 +3,6 @@
 This is a collection of Ansible playbooks, Terraform configurations and scripts to deploy and operate Incus clusters.
 
 ## How to get the test setup run:
-
 ### Install incus and OpenTofu
 Install incus stable or LTS on your system from the [zabbly/incus](https://github.com/zabbly/incus) release and initialize it on your local machine.
 
@@ -45,3 +44,47 @@ Run the Playbooks:
 ```
 ansible-playbook deploy.yaml
 ```
+
+NOTE: When re-deploying the same cluster (e.g. following a `terraform
+destroy`), you need to make sure to also clear any local state from the
+`data` directory, failure to do so will cause Ceph/OVN to attempt
+connection to the previously deployed systems which will cause the
+deployment to get stuck.
+
+## Deploying against production systems
+### Requirements (when using Incus with both Ceph and OVN)
+
+ - At least 3 servers
+ - One main network interface (or bond/VLAN), referred to as `enp5s0` in the examples
+ - One additional network interface (or bond/VLAN) to use for ingress into OVN, referred to as `enp6s0` in the examples
+ - Configured IPv4/IPv6 subnets on that additional network interface, in the examples, we're using:
+   - IPv4 subnet: `172.31.254.0/24`
+   - IPv4 gaterway: `172.31.254.1`
+   - IPv6 subnet: `fd00:1e4d:637d:1234::/64`
+   - IPv6 gateway: `fd00:1e4d:637d:1234::1`
+   - DNS server: `1.1.1.1`
+ - A minimum of 3 disks (or partitions) on distinct servers across the cluster for consumption by Ceph, in the examples, we're using (on each server):
+   - `nvme-QEMU_NVMe_Ctrl_incus_disk1`
+   - `nvme-QEMU_NVMe_Ctrl_incus_disk2`
+ - A minimum of 1 disk (or partition) on each server for local storage, that's `/dev/disk/by-id/nvme-QEMU_NVMe_Ctrl_incus_disk3` in the examples
+
+### Configuring Ansible
+
+With a deployment against physical servers, Terraform isn't currently used at all.
+Ansible will be used to deploy Ceph, OVN and Incus on the servers.
+
+You'll need to create a new `hosts.yaml` which you can base on the example one provided.
+
+You'll then need to do the following changes at minimum:
+ - Generate a new `ceph_fsid` (use `uuidgen`)
+ - Set a new `incus_name`
+ - Set a new `ovn_name`
+ - Update the number and name of servers to match the FQDN of your machines
+ - Ensure that you have 3 servers with the `mon` `ceph_role` and 3 servers with the `central` `ovn_role`
+ - Update the connection details to fit your deployment:
+   - Unset `ansible_connection`, `ansible_incus_remote`, `ansible_user` and `ansible_become` as those are specific to our test environment
+   - Set the appropriate connection information to access your servers (`ansible_connection`, `ansible_user`, SSH key, ...)
+ - Update the list of ceph and local disks for each servers (look at `/dev/disk/by-id` for identifiers)
+ - Tweak the `incus_init` variable to match your environment
+
+You'll find more details about the Ansible configuration options in [ansible/README.md](ansible/README.md).