This is unreleased documentation for SUSE® Storage 1.10 (Dev).

Configure Default Node and Disk Settings

This feature allows the user to customize the default disks and node configurations in SUSE Storage for newly added nodes using Kubernetes labels and annotations instead of the SUSE Storage UI or API.

Customizing the default configurations for disks and nodes is useful for scaling the cluster because it eliminates the need to configure SUSE Storage manually for each new node if the node contains more than one disk, or if the disk configuration is different for new nodes.

SUSE Storage will not keep the node labels or annotations in sync with the current Longhorn node disks or tags. Nor will SUSE Storage keep the node disks or tags in sync with the nodes, labels or annotations after the default disks or tags have been created.

Adding Node Tags to New Nodes

When a node does not have a tag, you can use a node annotation to set the node tags, as an alternative to using the SUSE Storage UI or API.

Scale up the Kubernetes cluster. The newly added nodes contain no node tags.
Add annotations to the new Kubernetes nodes that specify what the default node tags should be. The annotation format is:
```
node.longhorn.io/default-node-tags: <node tag list with JSON string format>
```
For example:
```
node.longhorn.io/default-node-tags: '["fast","storage"]'
```
Wait for SUSE Storage to sync the node tag automatically. If the node tag list was originally empty, SUSE Storage updates the node with the tag list, and you will see the tags for that node updated according to the annotation. If the node already had tags, you will see no change to the tag list.

Customizing Default Disks for New Nodes

SUSE Storage uses the Create Default Disk on Labeled Nodes setting to enable default disk customization.

If the setting is disabled, SUSE Storage will create a default disk using setting.default-data-path on all new nodes.

If the setting is enabled, SUSE Storage will decide to create the default disks or not, depending on the node’s label value of node.longhorn.io/create-default-disk.

If the node’s label value is true, SUSE Storage will create the default disk using settings.default-data-path on the node. If the node already has existing disks, SUSE Storage will not change anything.
If the node’s label value is config, SUSE Storage will check for the node.longhorn.io/default-disks-config annotation and create default disks according to it. If there is no annotation, or if the annotation is invalid, or the label value is invalid, SUSE Storage will not change anything.

The value of the label will be in effect only when the setting is enabled.

If the create-default-disk label is not set, the default disk will not be automatically created on the new nodes when the setting is enabled.

The configuration described in the annotation only takes effect when there are no existing disks or tags on the node.

If the label or annotation fails validation, the whole annotation is ignored.

Prerequisite

The SUSE Storage setting Create Default Disk on Labeled Nodes must be enabled.

Add new nodes to the Kubernetes cluster.
Add the label to the node. SUSE Storage relies on the label to decide how to customize default disks:
```
node.longhorn.io/create-default-disk: 'config'
```

Then add an annotation to the node. The annotation is used to specify the configuration of default disks. The format is:

node.longhorn.io/default-disks-config: <disks configuration with JSON string format>

For example, the following disk configuration can be specified in the annotation:

node.longhorn.io/default-disks-config:
'[
    {
        "path":"/mnt/disk1",
        "allowScheduling":true
    },
    {
        "name":"fast-ssd-disk",
        "path":"/mnt/disk2",
        "allowScheduling":false,
        "storageReserved":10485760,
        "tags":[
            "ssd",
            "fast"
        ]
    }
]'

If the same name is specified for different disks, the configuration will be treated as invalid.

Wait for SUSE Storage to create the customized default disks automatically, according to the annotation.

Launch SUSE Storage with multiple disks

Add the label to all nodes before launching SUSE Storage.
```
node.longhorn.io/create-default-disk: 'config'
```

Then add the disk config annotation to all nodes:

node.longhorn.io/default-disks-config: '[ { "path":"/var/lib/longhorn", "allowScheduling":true
  }, { "name":"fast-ssd-disk", "path":"/mnt/extra", "allowScheduling":false, "storageReserved":10485760,
  "tags":[ "ssd", "fast" ] }]'

Deploy SUSE Storage with create-default-disk-labeled-nodes: true, check here for customizing the default settings of SUSE Storage.