github.com/openshift/installer@v1.4.17/docs/user/agent/external-platform.md (about)

     1  # External platform configurations
     2  
     3  This document provides comprehensive details for configuring the external platform using the agent-based installer for OpenShift. It covers the minimum version requirement, 
     4  configuration options, and the generation of minimal ISOs for the specified platform.
     5  
     6  
     7  ## Minimum OpenShift Version
     8  The agent-based installer for OpenShift requires a minimum OpenShift version of 4.14 to support external platforms.
     9  
    10  ## Configuring the External Platform
    11  The external platform can be specified using either the install-config.yaml or by utilizing ZTP (Zero Touch Provisioning) manifests in agent-cluster-install.yaml. 
    12  When configuring the external platform, ensure that the platformName field is set to `oci`.
    13  
    14  __install-config.yaml__
    15  ```
    16  apiVersion: v1
    17  baseDomain: test.metalkube.org
    18  metadata:
    19    name: ostest
    20    namespace: cluster0
    21  ................
    22  ................
    23  ................
    24  ................
    25  platform:
    26      external:
    27        platformName: oci
    28  ```
    29  
    30  __agent-cluster-install.yaml__
    31  ```
    32  kind: AgentClusterInstall
    33  metadata:
    34    name: ostest
    35    namespace: cluster0
    36  spec:
    37    external:
    38      platformName: oci
    39  ................
    40  ................
    41  ................
    42  ................
    43  ```
    44  
    45  ## Generation of Minimal ISOs
    46  For the external platform, the agent-based installer always generates a minimal ISO, but may or may not generate the rootfs file explicitly. A minimal ISO is similar to the full ISO generated for other platforms, with the distinction that it does not contain the rootfs file within it.
    47  
    48  When generating the minimal ISO, the agent-based installer follows these steps:
    49  
    50  1. Deletes the rootfs image file from the RHCOS (Red Hat CoreOS) base ISO.
    51  2. Updates the grub configuration parameter `coreos.live.rootfs_url=` with the URL for the rootfs image file location.
    52  3. Users can specify the rootfs URL via an optional field named `bootArtifactsBaseURL` in the `agent-config.yaml`.
    53  
    54  # Downloading Rootfs Image
    55  When agent nodes are booted with the minimal ISO, the actual rootfs image file is dynamically downloaded into memory from the URL provided internally by the agent-based installer in the grub configuration.
    56  
    57  ## RootFS URL Configuration
    58  When running `openshift-install agent create image`
    59  
    60  - If the rootFS URL is specified via the `bootArtifactsBaseURL` field in `agent-config.yaml`, the agent-based installer embeds the specified URL into the grub configuration. It also generates a minimal ISO along with the rootfs.img file in the `boot-artifacts` directory. For IPV6 disconnected cluster installations, ensure that the agent-installer generated rootfs image file is uploaded to the URL specified in `bootArtifactsBaseURL` before booting the nodes with the minimal ISO.
    61  
    62  - If the rootFS URL is not specified via `bootArtifactsBaseURL` in `agent-config.yaml`, the agent-based installer embeds the default rootfs URL from the RHCOS streams file into the grub configuration. In this case, only a minimal ISO is generated. This is particularly useful for IPV4 connected cluster installations, as the default rootfs URL from the RHCOS streams is readily accessible in connected environments.