deprecated-helm-charts/stable/coredns

CoreDNS

CoreDNS is a DNS server that chains plugins and provides DNS Services

TL;DR;

$ helm install --name coredns --namespace=kube-system stable/coredns

Introduction

This chart bootstraps a CoreDNS deployment on a Kubernetes cluster using the Helm package manager. This chart will provide DNS Services and can be deployed in multiple configuration to support various scenarios listed below:

• CoreDNS as a cluster dns service and a drop-in replacement for Kube/SkyDNS. This is the default mode and CoreDNS is deployed as cluster-service in kube-system namespace. This mode is chosen by setting isClusterService to true.
• CoreDNS as an external dns service. In this mode CoreDNS is deployed as any kubernetes app in user specified namespace. The CoreDNS service can be exposed outside the cluster by using using either the NodePort or LoadBalancer type of service. This mode is chosen by setting isClusterService to false.
• CoreDNS as an external dns provider for kubernetes federation. This is a sub case of 'external dns service' which uses etcd plugin for CoreDNS backend. This deployment mode as a dependency on etcd-operator chart, which needs to be pre-installed.

Prerequisites

• Kubernetes 1.10 or later

Installing the Chart

The chart can be installed as follows:

$ helm install --name coredns --namespace=kube-system stable/coredns

The command deploys CoreDNS on the Kubernetes cluster in the default configuration. The configuration section lists various ways to override default configuration during deployment.

Tip

: List all releases using helm list

Uninstalling the Chart

To uninstall/delete the my-release deployment:

$ helm delete coredns

The command removes all the Kubernetes components associated with the chart and deletes the release.

Configuration

Parameter	Description	Default
image.repository	The image repository to pull from	coredns/coredns
image.tag	The image tag to pull from	v1.6.6
image.pullPolicy	Image pull policy	IfNotPresent
replicaCount	Number of replicas	1
resources.limits.cpu	Container maximum CPU	100m
resources.limits.memory	Container maximum memory	128Mi
resources.requests.cpu	Container requested CPU	100m
resources.requests.memory	Container requested memory	128Mi
serviceType	Kubernetes Service type	ClusterIP
prometheus.monitor.enabled	Set this to true to create ServiceMonitor for Prometheus operator	false
prometheus.monitor.additionalLabels	Additional labels that can be used so ServiceMonitor will be discovered by Prometheus	{}
prometheus.monitor.namespace	Selector to select which namespaces the Endpoints objects are discovered from.	""
service.clusterIP	IP address to assign to service	""
service.loadBalancerIP	IP address to assign to load balancer (if supported)	""
service.externalTrafficPolicy	Enable client source IP preservation	[]
service.annotations	Annotations to add to service	{prometheus.io/scrape: "true", prometheus.io/port: "9153"}
serviceAccount.create	If true, create & use serviceAccount	false
serviceAccount.name	If not set & create is true, use template fullname
rbac.create	If true, create & use RBAC resources	true
rbac.pspEnable	Specifies whether a PodSecurityPolicy should be created.	false
isClusterService	Specifies whether chart should be deployed as cluster-service or normal k8s app.	true
priorityClassName	Name of Priority Class to assign pods	nil
servers	Configuration for CoreDNS and plugins	See values.yml
affinity	Affinity settings for pod assignment	{}
nodeSelector	Node labels for pod assignment	{}
tolerations	Tolerations for pod assignment	[]
zoneFiles	Configure custom Zone files	[]
extraSecrets	Optional array of secrets to mount inside the CoreDNS container	[]
customLabels	Optional labels for Deployment, Pod, Service, ServiceMonitor objects	{}
See values.yaml for configuration notes. Specify each parameter using the --set key=value[,key=value] argument to helm install. For example,

$ helm install --name coredns \
  --set rbac.create=false \
    stable/coredns

The above command disables automatic creation of RBAC rules.

Alternatively, a YAML file that specifies the values for the above parameters can be provided while installing the chart. For example,

$ helm install --name coredns -f values.yaml stable/coredns

Tip

: You can use the default values.yaml

Caveats

The chart will automatically determine which protocols to listen on based on the protocols you define in your zones. This means that you could potentially use both "TCP" and "UDP" on a single port. Some cloud environments like "GCE" or "Azure container service" cannot create external loadbalancers with both "TCP" and "UDP" protocols. So When deploying CoreDNS with serviceType="LoadBalancer" on such cloud environments, make sure you do not attempt to use both protocols at the same time.