sureshanaparti commented on code in PR #458:
URL:
https://github.com/apache/cloudstack-documentation/pull/458#discussion_r2137438274
##########
source/plugins/cloudstack-kubernetes-service.rst:
##########
@@ -405,6 +450,266 @@ To remove an Instance from an ExternalManaged Kubernetes
cluster:
These operations are only supported for an ExternalManaged Kubernetes
Cluster
+.. _flexible-kubernetes-clusters:
+
+Flexible Kubernetes Clusters
+----------------------------
+
+From 4.21.0, many enhancements have been added to CloudStack Kubernetes
Service that allows users to:
+
+- Select the Hypervisor type for the Kubernetes Cluster nodes
+- Specify different templates and/or service offerings for different types of
Kubernetes Clusters nodes
+- Use CKS-ready custom templates for Kubernetes cluster nodes marked as 'For
CKS'
+- Separate etcd nodes from control nodes of the Kubernetes clusters
+- Add and remove a pre-created instance as a worker node to an existing
Kubernetes cluster
+- Mark Kubernetes cluster nodes for manual-only upgrade
+- Dedicate specific hosts/clusters to a specific domain for CKS cluster
deployment
+- Use diverse CNI plugins (Calico, Cilium, etc)
+
+Build a custom template to use for Kubernetes clusters nodes
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+CloudStack provides a custom CKS-ready template based on Ubuntu 22.04 to be
used for Kubernetes clusters nodes:
https://download.cloudstack.org/testing/custom_templates/ubuntu/22.04/.
+
+This template contains all the required packages to be used as a Kubernetes
cluster node. The default login credentials are: cloud:cloud.
+
+A user may decide not to use the provided CKS-ready template and build their
own template. The following needs to be made sure is present on the template:
+
+- The following packages or the equivalent ones for the specific OS need to be
installed:
+
+ .. code-block:: bash
+
+ cloud-init cloud-guest-utils conntrack apt-transport-https
ca-certificates curl gnupg gnupg-agent software-properties-common gnupg
lsb-release python3-json-pointer python3-jsonschema containerd.io
+
+- A user named `cloud` needs to be created and added to the sudoers list:
+
+ .. code-block:: bash
+
+ sudo useradd -m -s /bin/bash cloud
+ echo "cloud:<password>" | sudo chpasswd
+
+ # Edit /etc/sudoers file with:
+ cloud ALL=(ALL) NOPASSWD:ALL
+
+- Create the necessary directory /opt/bin:
+
+ .. code-block:: bash
+
+ sudo mkdir -p /opt/bin
+
+- Once the VM is deployed, place the Management Server’s SSH Public key at the
cloud user’s authorized_keys file at ~/.ssh/authorized_keys
+
+
+Registering a custom template for Kubernetes cluster nodes
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+By default, the Kubernetes clusters nodes are deployed from the System VM
template. On the Advanced Settings for Kubernetes clusters creation, CloudStack
allows selecting templates for different types of nodes.
+
+To register a template that will be listed as an option for Kubernetes cluster
nodes:
+
+- Set URL to the provided CKS-ready template at:
https://download.cloudstack.org/testing/custom_templates/ubuntu/22.04/ or a
custom template built from the section above.
+
+- Set the template specific values as usual for template registration.
+
+- Mark the option 'For CKS'. This ensures the template is considered as an
option for Kubernetes cluster nodes on the Advanced Settings section for
clusters creation.
+
+|cks-custom-template-registration.png|
+
+Separate etcd nodes from control nodes
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+By default, a CKS cluster has 0 dedicated etcd nodes, and the etcd service
runs on the control nodes. If etcd node count is set to a value greater than or
equal to 1 during cluster creation, CloudStack will provision separate nodes
exclusively for the etcd service, isolating them from the control nodes with
the desired template and service offering if specified.
+
+To use separate etcd nodes, it is required to build and register a CKS ISO
version containing the etcd binaries as explained in:
:ref:`kubernetes-supported-versions`
+
+For convenience, some CKS ISOs are uploaded to:
https://download.cloudstack.org/testing/cks/custom_templates/iso-etcd/
+
+Add an external VM Instance as a worker node to a Kubernetes cluster
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Requirements for a VM Instance to be added as worker node to a Kubernetes
cluster:
+
+- At least 8GB ROOT disk size, 2 CPU cores and 2GB RAM
+
+- The VM Instance must have a NIC on the Kubernetes cluster network
+
+- **The Management Server’s SSH Public key must be added at the cloud user’s
authorized_keys file at `~/.ssh/authorized_keys`**.
+
+The VM Instances meeting the requirements above can be added to the Kubernetes
cluster by the `addNodesToKubernetesCluster` API specifying:
+
+- **id** (UUID of the Kubernetes cluster. Required)
+- **nodeids** (comma separated list of (external) node (physical or virtual
machines) IDs that need to be added as worker nodes to an existing managed
Kubernetes cluster (CKS). Required)
+- **mountcksisoonvr** (optional parameter for Vmware only, uses the CKS
cluster network VR to mount the CKS ISO)
+- **manualupgrade** (optional parameter that indicates if the node is marked
for manual upgrade and excluded from the Kubernetes cluster upgrade operation)
+
+.. note::
+ Users will have the ability to add nodes to the Kubernetes cluster and mark
them for manual upgrade. Once the nodes are marked for manual upgrade, the
future cluster upgrade operations will exclude these nodes i.e., the Kubernetes
version won't be upgraded.
+
+The following course of actions are taken:
+
+- Validation: The external node(s) are validated to ensure that all the
above-mentioned prerequisites are present
+
+- Addition of port-forwarding rules and firewall rules (for isolated networks)
+
+- VM is rebooted with the Kubernetes configuration passed as userdata
Review Comment:
```suggestion
- VM is rebooted with the Kubernetes configuration passed as user data
```
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