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ELMA365 On-Premises > ELMA365 On-Premises Enterprise > Install add-on components for ELMA365 / Install NodeLocal DNS Cache

Install NodeLocal DNS Cache

NodeLocal DNS Cache helps reduce the load on DNS queries within a Kubernetes cluster. NodeLocal DNS enhances the stability of DNS name resolution, which in turn can avoid DNAT rules, connection tracking, and connection count limits.

начало внимание 

For Kubernetes clusters deployed on the Deckhouse platform, the installation of NodeLocal DNS is not required. In this case, use the built-in module.

конец внимание 

The installation consists of four steps:

  1. Get the IP address of the kube-dns service.
  2. Download the Helm chart and configuration file.
  3. Fill out the configuration file.
  4. Install the Node Local DNS chart using Helm in the Kubernetes cluster.

Step 1: Get the IP address of the kube-dns service

The kube-dns service is typically located in the namespace kube-system of the Kubernetes cluster.

Determine the IP address of the kube-dns service by executing the command:

kubectl get svc kube-dns -n kube-system -o jsonpath={.spec.clusterIP}

The result of the command should be the IP address, which will be used in Step 3. In the context of this article, the result of the command is the IP address 172.20.0.10.

Step 2: Download the Helm chart and configuration file

For installation via the internet, obtain the configuration file values-nodelocal-dns.yaml by executing the command:

helm repo add elma365 https://charts.elma365.tech
helm repo update
helm show values elma365/node-local-dns > values-nodelocal-dns.yaml

Getting the configuration file for installation in a closed-loop environment without internet access

  1. On a computer with internet access, download the ELMA365 images and upload them to the local image registry by executing the following command:

helm repo add elma365 https://charts.elma365.tech
helm repo update
helm pull elma365/node-local-dns

For more details, see Download ELMA365 images.

  1. Copy the downloaded chart archive node-local-dns-X.Y.Z.tgz to the server where the installation will be performed.
  1. Unpack this chart and copy the default configuration file values.yaml to values-nodelocal-dns.yaml:

tar -xf node-local-dns-X.Y.Z.tgz
cp node-local-dns/values.yaml values-nodelocal-dns.yaml

Step 3: Fill out the configuration file

Fill out the configuration file values-nodelocal-dns.yaml for the installation of NodeLocal DNS Cache.

## NodeLocal DNS Cache settings
node-local-dns:
  config:
    ## cluster domain
    dnsDomain: "cluster.local"
    ## IP address of kube-dns service
    dnsServer: "172.20.0.10"
    ## IP address for NodeLocal DNS Cache.
    localDns: "169.254.20.25"

where:

  • node-local-dns.config.dnsDomain is the domain of the Kubernetes cluster;
  • node-local-dns.config.dnsServer is the IP address of the kube-dns service, obtained in Step 1;
  • node-local-dns.config.localDns is the local IP address for NodeLocal DNS Cache.

Filling out connection parameters to the private registry for installation in a closed-loop environment without internet access

To connect to the private registry, you need to:

  1. Download ELMA365 images and upload them to the local image registry. For more details, see Download ELMA365 images.
  2. Set the address and path for the parameter node-local-dns.image.repository.
  1. Indicate the name of the secret with access rights to the private registry in the parameter node-local-dns.imagePullSecrets. The secret must be created manually and encrypted in Base64.

## NodeLocal DNS Cache settings
node-local-dns:
  ## Connection parameters to the private registry
  image:
    ## address and path for the private registry
    repository: registry.example.com/dns/k8s-dns-node-cache
  ## The secret with access rights to the private registry must be created manually, encrypted in Base64
  imagePullSecrets:
    - myRegistryKeySecretName

where repository format is:

  • address is registry.example.com;
  • path is /dns/k8s-dns-node-cache.

Step 4: Install the Node Local DNS chart using Helm in the Kubernetes cluster

Perform the installation of the Node Local DNS chart in namespace kube-system.

For online installation:

helm upgrade --install nodelocaldns elma365/node-local-dns -f values-nodelocal-dns.yaml -n kube-system

For offline installation without internet access:

helm upgrade --install nodelocaldns ./node-local-dns -f values-nodelocal-dns.yaml -n kube-system

Delete Node Local DNS chart using helm in the Kubernetes cluster

To remove the Node Local DNS chart in namespace kube-system, execute the command:

helm uninstall nodelocaldns -n kube-system

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