HCIDOCS-75: Add IPI installation workflow information to our documentation

Author: kdrake20

installing/installing_bare_metal/ipi/ipi-install-prerequisites.adoc

@@ -60,3 +60,5 @@ include::modules/ipi-install-out-of-band-management.adoc[leveloffset=+1]
 include::modules/ipi-install-required-data-for-installation.adoc[leveloffset=+1]
 
 include::modules/ipi-install-validation-checklist-for-nodes.adoc[leveloffset=+1]
+
+include::modules/con_ipi-installation-workflow.adoc[leveloffset=+1]

modules/con_ipi-installation-workflow.adoc

@@ -0,0 +1,48 @@
+// Module included in the following assemblies:
+//
+// * installing/installing_bare_metal/ipi/ipi-install-prerequisites.adoc
+
+:_mod-docs-content-type: CONCEPT
+
+[id="installation-workflow_{context}"]
+= Installation workflow
+
+The installation program supports interactive mode, but it is recommended to prepare an `install-config.yaml` file in advance, containing the provisioning details for all of the bare-metal hosts.
+
+The administrator adds the relevant cluster details to the `install-config.yaml` file. The `install-config.yaml` file is shipped to the provisioning host. The administrator generates the manifests and verifies all prerequisites.
+
+The installation program enrolls all nodes in the cluster and starts the bootstrap VM. Metal platform components are started as `systemd` services, which have the following containers:
+
+* Ironic-dnsmasq: DHCP server responsible for handing over the IP addresses to the provisioning interface of various nodes on the provisioning network. Ironic-dnsmasq is only enabled when the `provisioningNetwork` is enabled.
+* Ironic-httpd: http server used to ship the images to the nodes.
+* Image-customization
+* Ironic
+* Ironic-inspector (available in {openshift} 4.16 and earlier)
+* Ironic-ramdisk-logs
+* Extract-machine-os
+* Provisioning-interface: Service that configures networking when the provisioning interface is enabled.
+* Metal3-baremetal-operator: Operator that provides a higher-level API for Ironic and replaces `terraform-provider-ironic` (available in {openshift} 4.16 and later)
+
+The nodes enter the validation phase. The nodes move to a “manageable” state after Ironic validates the credentials to access the Baseboard Management Controller (BMC) for each node.
+
+Once in the “manageable” state, the “inspection” phase starts. The "inspection" phase ensures that the hardware meets the minimum requirements needed for a successful deployment of {ocp}.
+
+The `install-config.yaml` file details the provisioning network. The installation program on the bootstrap VM will try to push a live image to every node with the Ironic Python Agent (IPA) loaded in the RAM. When using virtual media, the live image connects directly to the BMC.
+
+When using PXE boot, all nodes reboot to start the process:
+
+* The `ironic-dnsmasq` service running on the bootstrap VM provides the IP address of the node and the TFTP boot server.
+* The first boot software loads the root file system over HTTP.
+* The `ironic` service on the bootstrap VM receives the hardware information from each node.
+
+The nodes then enter the “cleaning” state, where each node must clean all the disks before continuing with the configuration.
+
+Once the “cleaning” state finishes, the nodes enter the “available” state and the installation program moves the nodes to the “deploying” state.
+
+IPA runs the coreos-installer to install the RHCOS image on the disk defined by `rootDeviceHints` in the `install-config.yaml` file. The node boots into the new RHCOS.
+
+Once the control plane nodes are configured, control moves to the control plane nodes and the bootstrap is removed.
+
+The baremetal-operator continues the deployment of the workers, storage and infra nodes. Once the installation completes, the nodes move to the "active" state.
+
+The administrator performs the postinstallation checks and proceeds with Day 2 tasks.