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Registration Pull Mode

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Sveltos Cluster Registration Pull Mode

Sveltos supports managed cluster registration in Pull Mode. In this model, managed clusters actively pull configuration and add-ons from a central source, rather than having the management cluster push them directly to the managed clusters.

The Pull Mode is ideal for managed clusters behind a firewall, in air-gapped environments, edge deployments with limited bandwidth or highly regulated and secure setups.

If Sveltos is not already installed, have a look at the installation details located here.

How does it work?

While the core Sveltos controllers run in a management cluster and orchestrate deployments, the concept of Pull Mode becomes relevant when managing clusters in challenging network environments such as firewalled, air-gapped, or edge deployments, where direct inbound access from the management cluster to the managed clusters is either not possible or not desired.

This is how the Pull Mode flow works:

  1. Management Cluster: It defines the desired state. We define our ClusterProfile/Profile resources in the management cluster, specifying which add-ons and configurations should be applied to which managed clusters by utilising the Kubernetes labels selection concept.
  2. Managed Cluster: Rather than the management cluster initiating all deployments, a component on the managed cluster initiates a connection to the management cluster.
  3. Configuration Fetching: The managed cluster pulls the relevant configuration, manifest, or Helm chart from the management cluster.
  4. Apply: The managed cluster's local agent or component applies the pulled configurations to the cluster.

Sveltos Pull Mode

Advantages

The following items are some of the benefits of utilising Sveltos in Pull Mode.

  • Firewalled and Air-Gapped Environments: This is the primary driver. When managed clusters are behind firewalls or in air-gapped networks, direct inbound connections from a central management cluster are not possible. Sveltos in Pull Mode allows the managed clusters to reach out to the management cluster or a Git repository to obtain deployment instructions.
  • Edge Deployments: For edge locations with intermittent connectivity or limited network bandwidth, the Sveltos Pull Mode offers resilience.
  • Security: Reducing the need for inbound ports to managed clusters enhances the security posture of an environment by minimising the attack surface.

Register Cluster

sveltosctl Registration

It is recommended, but not required, to use the sveltosctl for cluster registration. Alternatively, to programmatically register clusters, consult the section.

$ sveltosctl register cluster \
    --namespace=monitoring \
    --cluster=prod-cluster \
    --pullmode \
    --labels=environment=production,tier=backend \
    > sveltoscluster_registration.yaml
Parameter Description
--namespace The namespace in the management cluster where Sveltos stores information about the registered cluster.
--cluster The name of the cluster to identify the registered cluster within Sveltos.
--pullmode Enables the Sveltos Pull Mode registration.
--labels (Optional) Comma-separated key-value pairs to define labels for the registered cluster.

Once the .yaml file is generated, apply it to the Kubernetes managed cluster.

$ export KUBECONFIG=</path/to/kubeconfig/managed/cluster>
$ kubectl apply -f sveltoscluster_registration.yaml

Note

Test the Pull Mode with up to two managed clusters for free. Need more than two clusters? Contact us at support@projectsveltos.io to explore license options based on your needs!

Programmatic Registration

To programmatically register clusters with Sveltos in Pull Mode, create the below resource and apply it to the managed cluster.

  • SveltosCluster: Represent your cluster as an SveltosCluster instance.

SveltosCluster

---
apiVersion: lib.projectsveltos.io/v1beta1
kind: SveltosCluster
metadata:
  name: YOUR-CLUSTER-NAME
  namespace: YOUR-CLUSTER-NAMESPACE
  labels:
    environment: production
    tier: backend
spec:
  pullMode: true