--- layout: docs page_title: Resolve Consul DNS requests in Kubernetes description: >- Use a k8s ConfigMap to configure KubeDNS or CoreDNS so that you can use Consul's `.service.consul` syntax for queries and other DNS requests. In Kubernetes, this process uses either stub-domain or proxy configuration. --- # Resolve Consul DNS requests in Kubernetes One of the primary query interfaces to Consul is the [DNS interface](/docs/discovery/dns). You can configure Consul DNS in Kubernetes using a [stub-domain configuration](https://kubernetes.io/docs/tasks/administer-cluster/dns-custom-nameservers/#configure-stub-domain-and-upstream-dns-servers) if using KubeDNS or a [proxy configuration](https://coredns.io/plugins/proxy/) if using CoreDNS. Once configured, DNS requests in the form `.service.consul` will resolve for services in Consul. This will work from all Kubernetes namespaces. -> **Note:** If you want requests to just `` (without the `.service.consul`) to resolve, then you'll need to turn on [Consul to Kubernetes Service Sync](/docs/k8s/service-sync#consul-to-kubernetes). ## Consul DNS Cluster IP To configure KubeDNS or CoreDNS you'll first need the `ClusterIP` of the Consul DNS service created by the [Helm chart](/docs/k8s/helm). The default name of the Consul DNS service will be `consul-dns`. Use that name to get the `ClusterIP`: ```shell-session $ kubectl get svc consul-dns --output jsonpath='{.spec.clusterIP}' 10.35.240.78% ``` For this installation the `ClusterIP` is `10.35.240.78`. -> **Note:** If you've installed Consul using a different helm release name than `consul` then the DNS service name will be `-consul-dns`. ## KubeDNS If using KubeDNS, you need to create a `ConfigMap` that tells KubeDNS to use the Consul DNS service to resolve all domains ending with `.consul`: Export the Consul DNS IP as an environment variable: ```bash export CONSUL_DNS_IP=10.35.240.78 ``` And create the `ConfigMap`: ```shell-session $ cat < **Note:** The `stubDomain` can only point to a static IP. If the cluster IP of the Consul DNS service changes, then it must be updated in the config map to match the new service IP for this to continue working. This can happen if the service is deleted and recreated, such as in full cluster rebuilds. -> **Note:** If using a different zone than `.consul`, change the stub domain to that zone. Now skip ahead to the [Verifying DNS Works](#verifying-dns-works) section. ## CoreDNS Configuration If using CoreDNS instead of KubeDNS in your Kubernetes cluster, you will need to update your existing `coredns` ConfigMap in the `kube-system` namespace to include a `forward` definition for `consul` that points to the cluster IP of the Consul DNS service. Edit the `ConfigMap`: ```shell-session $ kubectl edit configmap coredns --namespace kube-system ``` And add the `consul` block below the default `.:53` block and replace `` with the DNS Service's IP address you found previously. ```diff apiVersion: v1 kind: ConfigMap metadata: labels: addonmanager.kubernetes.io/mode: EnsureExists name: coredns namespace: kube-system data: Corefile: | .:53 { } + consul { + errors + cache 30 + forward . + } ``` -> **Note:** The consul proxy can only point to a static IP. If the cluster IP of the `consul-dns` service changes, then it must be updated to the new IP to continue working. This can happen if the service is deleted and recreated, such as in full cluster rebuilds. -> **Note:** If using a different zone than `.consul`, change the key accordingly. ## Verifying DNS Works To verify DNS works, run a simple job to query DNS. Save the following job to the file `job.yaml` and run it: ```yaml apiVersion: batch/v1 kind: Job metadata: name: dns spec: template: spec: containers: - name: dns image: anubhavmishra/tiny-tools command: ['dig', 'consul.service.consul'] restartPolicy: Never backoffLimit: 4 ``` ```shell-session $ kubectl apply --filename job.yaml ``` Then query the pod name for the job and check the logs. You should see output similar to the following showing a successful DNS query. If you see any errors, then DNS is not configured properly. ```shell-session $ kubectl get pods --show-all | grep dns dns-lkgzl 0/1 Completed 0 6m $ kubectl logs dns-lkgzl ; <<>> DiG 9.11.2-P1 <<>> consul.service.consul ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4489 ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 4 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ;; QUESTION SECTION: ;consul.service.consul. IN A ;; ANSWER SECTION: consul.service.consul. 0 IN A 10.36.2.23 consul.service.consul. 0 IN A 10.36.4.12 consul.service.consul. 0 IN A 10.36.0.11 ;; ADDITIONAL SECTION: consul.service.consul. 0 IN TXT "consul-network-segment=" consul.service.consul. 0 IN TXT "consul-network-segment=" consul.service.consul. 0 IN TXT "consul-network-segment=" ;; Query time: 5 msec ;; SERVER: 10.39.240.10#53(10.39.240.10) ;; WHEN: Wed Sep 12 02:12:30 UTC 2018 ;; MSG SIZE rcvd: 206 ```