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ExternalDNS synchronizes exposed Kubernetes Services and Ingresses with DNS providers.
This README is a part of the complete documentation, available here and DeepWiki.
Inspired by Kubernetes DNS, Kubernetes' cluster-internal DNS server, ExternalDNS makes Kubernetes resources discoverable via public DNS servers. Like KubeDNS, it retrieves a list of resources (Services, Ingresses, etc.) from the Kubernetes API to determine a desired list of DNS records. Unlike KubeDNS, however, it's not a DNS server itself, but merely configures other DNS providers accordingly—e.g. AWS Route 53 or Google Cloud DNS.
In a broader sense, ExternalDNS allows you to control DNS records dynamically via Kubernetes resources in a DNS provider-agnostic way.
The FAQ contains additional information and addresses several questions about key concepts of ExternalDNS.
To see ExternalDNS in action, have a look at this video or read this blogpost.
ExternalDNS allows you to keep selected zones (via --domain-filter) synchronized with Ingresses and Services of type=LoadBalancer and nodes in many DNS providers. See In-tree providers for the built-in list, and New providers for webhook-based ones.
ExternalDNS is, by default, aware of the records it is managing, therefore it can safely manage non-empty hosted zones.
We strongly encourage you to set --txt-owner-id to a unique value that doesn't change for the lifetime of your cluster.
You might also want to run ExternalDNS in a dry run mode (--dry-run flag) to see the changes to be submitted to your DNS Provider API.
Note that all flags can be replaced with environment variables; for instance,
--dry-run could be replaced with EXTERNAL_DNS_DRY_RUN=1.
ExternalDNS runs as a controller in your cluster, and can also be run locally to test a configuration. For provider-specific setup, see the In-tree providers table (each row links its tutorial) or the webhook providers. More tutorials — ingress controllers, sources, and provider extras — are in the full documentation.
Running Locally
See the contributor guide for details on compiling from source.
Next, run an application and expose it via a Kubernetes Service:
kubectl run nginx --image=nginx --port=80
kubectl expose pod nginx --port=80 --target-port=80 --type=LoadBalancerAnnotate the Service with your desired external DNS name. Make sure to change example.org to your domain.
kubectl annotate service nginx "external-dns.kubernetes.io/hostname=nginx.example.org."Optionally, you can customize the TTL value of the resulting DNS record by using the external-dns.kubernetes.io/ttl annotation:
kubectl annotate service nginx "external-dns.kubernetes.io/ttl=10"For more details on configuring TTL, see advanced ttl.
Use the internal-hostname annotation to create DNS records with ClusterIP as the target.
kubectl annotate service nginx "external-dns.kubernetes.io/internal-hostname=nginx.internal.example.org."If the service is not of type Loadbalancer you need the --publish-internal-services flag.
Locally run a single sync loop of ExternalDNS.
external-dns --txt-owner-id my-cluster-id --provider google --google-project example-project --source service --once --dry-runThis should output the DNS records it will modify to match the managed zone with the DNS records you desire.
It also assumes you are running in the default namespace. See the FAQ for more information regarding namespaces.
Note: TXT records will have the my-cluster-id value embedded. Those are used to ensure that ExternalDNS is aware of the records it manages.
Once you're satisfied with the result, you can run ExternalDNS like you would run it in your cluster: as a control loop, and not in dry-run mode:
external-dns --txt-owner-id my-cluster-id --provider google --google-project example-project --source serviceCheck that ExternalDNS has created the desired DNS record for your Service and that it points to its load balancer's IP. Then try to resolve it:
dig +short nginx.example.org.
104.155.60.49Now you can experiment and watch how ExternalDNS makes sure that your DNS records are configured as desired. Here are a couple of things you can try out:
- Change the desired hostname by modifying the Service's annotation.
- Recreate the Service and see that the DNS record will be updated to point to the new load balancer IP.
- Add another Service to create more DNS records.
- Remove Services to clean up your managed zone.
If using a txt registry and attempting to use a CNAME the --txt-prefix must be set to avoid conflicts. Changing --txt-prefix will result in lost ownership over previously created records.
If externalIPs list is defined for a LoadBalancer service, this list will be used instead of an assigned load balancer IP to create a DNS record.
It's useful when you run bare metal Kubernetes clusters behind NAT or in a similar setup, where a load balancer IP differs from a public IP (e.g. with MetalLB).
No new provider will be added to ExternalDNS in-tree.
ExternalDNS has introduced a webhook system, which can be used to add a new provider. See PR #3063 for all the discussions about it.
Some known providers using webhooks are the ones in the table below.
NOTE: The maintainers of ExternalDNS have not reviewed those providers, use them at your own risk and following the license and usage recommendations provided by the respective projects. The maintainers of ExternalDNS take no responsibility for any issue or damage from the usage of any externally developed webhook.
ExternalDNS supports the DNS providers below, implemented by the ExternalDNS contributors.
Maintaining all of these in a central repository introduces lots of toil and potential risks, so external-dns has begun moving providers out of tree (see #4347).
No new in-tree providers are accepted; use the webhook system instead.
Those interested can create a webhook provider based on an in-tree provider and submit a PR to reference it in the table above. Providers without a maintainer listed are in need of assistance.
| Provider | Maintainers | Tutorials |
|---|---|---|
| Alibaba Cloud DNS | guide | |
| AWS Cloud Map | guide | |
| AWS Route 53 | Route 53, public & private zones, filters, LocalStack, Load Balancer Controller, kube-ingress-aws | |
| AzureDNS | Azure DNS, Private DNS | |
| Civo | @alejandrojnm | guide |
| CloudFlare | guide | |
| CoreDNS | guide, etcd backend | |
| DNSimple | guide | |
| Exoscale | guide | |
| Gandi | @packi | guide |
| GoDaddy | guide | |
| Google Cloud DNS | GKE default ingress, GKE with nginx | |
| Linode DNS | guide | |
| NS1 | guide | |
| Oracle Cloud Infrastructure DNS | guide | |
| OVHcloud | @rbeuque74 | guide |
| Pi-hole | @tinyzimmer | guide |
| PowerDNS | guide | |
| RFC2136 | guide | |
| Scaleway DNS | @Sh4d1 | guide |
ExternalDNS reads Kubernetes resources from one or more sources (set via --source) and turns them into the desired DNS records.
See the sources documentation for the full list and configuration details.
Breaking changes were introduced in external-dns in the following versions:
v0.10.0: use ofnetworking.k8s.io/ingressesinstead ofextensions/ingresses(see #2281)v0.18.0: use ofdiscovery.k8s.io/endpointslicesinstead ofendpoints(see #5493)v0.19.0: don't expose internal ipv6 by default (see #5575) and disable legacy listeners ontraefik.containo.usAPI Group (see #5565)
| ExternalDNS | ≤ 0.9.x | ≥ 0.10.x and ≤ 0.17.x | ≥ 0.18.x |
|---|---|---|---|
| Kubernetes ≤ 1.18 | ✅ | ❌ | ❌ |
| Kubernetes 1.19 and 1.20 | ✅ | ✅ | ❌ |
| Kubernetes 1.21 | ✅ | ✅ | ✅ |
| Kubernetes ≥ 1.22 and ≤ 1.32 | ❌ | ✅ | ✅ |
| Kubernetes ≥ 1.33 | ❌ | ❌ | ✅ |
Are you interested in contributing to external-dns? We, the maintainers and community, would love your suggestions, contributions, and help! Also, the maintainers can be contacted at any time to learn more about how to get involved.
We also encourage ALL active community participants to act as if they are maintainers, even if you don't have "official" write permissions. This is a community effort, we are here to serve the Kubernetes community. If you have an active interest and you want to get involved, you have real power! Don't assume that the only people who can get things done around here are the "maintainers". We also would love to add more "official" maintainers, so show us what you can do!
The external-dns project is currently in need of maintainers for specific DNS providers. Ideally each provider would have at least two maintainers. It would be nice if the maintainers run the provider in production, but it is not strictly required. Providers in the in-tree providers table that do not have a maintainer listed are in need of assistance.
Read the contributing guidelines and have a look at the contributing docs to learn about building the project, the project structure, and the purpose of each package.
For the release process, see docs/release.md.
For an overview on how to write new Sources and Providers check out Sources and Providers.
ExternalDNS is an effort to unify the following similar projects in order to bring the Kubernetes community an easy and predictable way of managing DNS records across cloud providers based on their Kubernetes resources:
- Kops' DNS Controller
- Zalando's Mate
- Molecule Software's route53-kubernetes
- A full demo on GKE Kubernetes. See How-to Kubernetes with DNS management (ssl-manager pre-req)
- Run external-dns on GKE with workload identity. See Kubernetes, ingress-nginx, cert-manager & external-dns
- ExternalDNS integration with Azure DNS using workload identity