Available in editions:  BE, SE, SE+, EE

The module lifecycle stage: General Availability

  • The module works with all CNIs, but in order to work correctly with cni-cilium, a number of conditions must be met.
  • By default, when used together with the cni-simple-bridge or cni-flannel modules, the node-local-dns module does not work for requests from hostNetwork. In this case, all requests go to the kube-dns module. You can specify the address 169.254.20.10 in the pod configuration, but if node-local-dns module crashes, there will be no fallback to the kube-dns module.

The module has 5 alerts.

The module is enabled by default in the Default bundle. The module is disabled by default in the following bundles: Managed, Minimal.

How to explicitly enable the module…

You may explicitly enable or disable the module in one of the following ways:

  • Via Deckhouse web UI. In the “System” → “System Management” → “Deckhouse” → “Modules” section, open the node-local-dns module and enable (or disable) the “Module enabled” toggle. Save changes.

    Example:

    Module enable/disable interface

  • Via Deckhouse CLI (d8).

    Use the d8 system module enable command for enabling, or d8 system module disable command for disabling the module (you need Deckhouse CLI (d8), configured to work with the cluster).

    Example of enabling the module:

    d8 system module enable node-local-dns

  • Using ModuleConfig node-local-dns.

    Set spec.enabled to true or false in ModuleConfig node-local-dns (create it if necessary);

    Example of a manifest to enable module node-local-dns:

    apiVersion: deckhouse.io/v1alpha1
kind: ModuleConfig
metadata:
  name: node-local-dns
spec:
  enabled: true

How to configure the module…

You can configure the module in one of the following ways:

  • Via Deckhouse web UI.

    In the “System” → “System Management” → “Deckhouse” → “Modules” section, open the node-local-dns module and enable the “Advanced Settings” switch. Fill in the required fields in the “Configuration” tab or specify the module settings in YAML format on the “YAML” tab, excluding the settings section. Save the changes.

    Example:

    Module Setup Interface

    You can also edit the ModuleConfig object node-local-dns on the “YAML” tab in the module settings window (“System” → “System Management” → “Deckhouse” → “Modules”, open the module node-local-dns) by specifying the schema version in the spec.version parameter and the necessary module parameters in the spec.settings section.

  • Via Deckhouse CLI (d8) (requires Deckhouse CLI (d8) configured to work with the cluster).

    Edit the existing ModuleConfig node-local-dns (for more details on configuring Deckhouse, see the documentation) by executing the following command:

    d8 k edit mc node-local-dns

    Make the necessary changes in the spec.settings section. If necessary, specify the schema version in the spec.version parameter. Save the changes.

    You can also create a file with manifest for ModuleConfig node-local-dns using the example below. Fill in the spec.settings section with the required module parameters. If necessary, specify the schema version in the spec.version parameter.

    Apply the manifest using the following command (indicate the manifest file name):

    d8 k apply -f <FILENAME>

    Example of a manifest for ModuleConfig node-local-dns:

    apiVersion: deckhouse.io/v1alpha1
kind: ModuleConfig
metadata:
  name: node-local-dns
spec:
  version: 1
  enabled: true
  settings: # Module parameters from the "Parameters" section below.

Requirements

To the versions of other modules:

  • kube-dns: any version.

Parameters

Schema version: 1

  • settings
    object
    • settings.enableLogs
      boolean

      Enables query logging for node-local-dns instances.

      Default: false

    • settings.highAvailability
      boolean

      Manual failover mode management. Within this module, the option affects the DNS records caching mechanism on nodes:

      • true: upon the expiration of the TTL for an individual DNS record, node-local-dns will continue to return the “stale” value immediately while simultaneously requesting a fresh value from the upstream kube-dns. Thus, in the event of issues with the nodes where kube-dns is running, applications will continue to receive responses to DNS queries with expired TTL, but without delay.
      • false: upon the expiration of the TTL for an individual DNS record, node-local-dns will continue to return the “stale” value, but only after querying the upstream kube-dns. Thus, in the event of issues with the nodes where kube-dns is running, applications will continue to receive DNS responses with expired TTL, but with potentially significant delay. This approach is suitable in highly dynamic environments where Services and Namespaces are frequently recreated.

      By default, Deckhouse automatically decides whether to enable the HA mode. Click here to learn more about the HA mode for modules.

      Example:

      highAvailability: true