https://github.com/wikiwi/kube-dns-sync

Controller syncing Kubernetes Node IPs to a DNS service
https://github.com/wikiwi/kube-dns-sync

Last synced: about 2 months ago
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Controller syncing Kubernetes Node IPs to a DNS service

• Host: GitHub
• URL: https://github.com/wikiwi/kube-dns-sync
• Owner: wikiwi
• License: mit
• Created: 2016-07-21T12:18:10.000Z (over 8 years ago)
• Default Branch: master
• Last Pushed: 2016-07-29T04:32:22.000Z (over 8 years ago)
• Last Synced: 2024-08-04T18:01:11.315Z (5 months ago)
• Language: Go
• Size: 53.7 KB
• Stars: 5
• Watchers: 3
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# kube-dns-sync

`kube-dns-sync` is a Kubernetes Controller that syncs Kubernetes Node IPs to a DNS service.

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[Build Status]: https://travis-ci.org/wikiwi/kube-dns-sync

[Build Status Widget]: https://travis-ci.org/wikiwi/kube-dns-sync.svg?branch=master

[Coverage Status]: https://coveralls.io/github/wikiwi/kube-dns-sync?branch=master

[Coverage Status Widget]: https://coveralls.io/repos/github/wikiwi/kube-dns-sync/badge.svg?branch=master

[Code Climate]: https://codeclimate.com/github/wikiwi/kube-dns-sync

[Code Climate Widget]: https://codeclimate.com/github/wikiwi/kube-dns-sync/badges/gpa.svg

[MicroBadger URL]: http://microbadger.com/#/images/wikiwi/kube-dns-sync

[MicroBadger Version Widget]: https://images.microbadger.com/badges/version/wikiwi/kube-dns-sync.svg

[MicroBadger Image Widget]: https://images.microbadger.com/badges/image/wikiwi/kube-dns-sync.svg

## Use-Case

- You want to avoid using a load balancer or can't use one to expose your Kubernetes Services.

- You want to expose your Kubernetes Services using `NodePort` and need a way to discover the Nodes.

- You need to access your Nodes using a fixed DNS record.

## How it works

`kube-dns-sync` watches the Kubernetes API for changes in the Node resources and syncs the IP addresses to the DNS zone. When `--apex-address-type` is set, `kube-dns-sync` will sync the IP addresses of specified type from the Nodes to the A Record of the apex zone (root domain). Setting `--address-types` will create a managed A Record for each specifed type e.g. `internalip.example.com.`, `externalip.example.com.` with the addresses from each Node.

## Disadvantages

- `kube-dns-sync` only checks the health of Nodes and is unaware of your application.

- DNS changes are slow to propagate to clients. During this delay your clients might receive DNS records of unhealthy or removed Nodes.

## Supported DNS service

`kube-dns-sync` uses the DNS module of Kubernetes Federation and therefore supports the same DNS services. At the time of writing the supported services are 'google-clouddns' and 'aws-route53'.

## Authorization

The authorization mechanics are the same as for Kubernetes Federation. A link will be put here as soon as Kubernetes releases an official documentation for its Federation Service.

*note:* `google-clouddns` requires the scope `https://www.googleapis.com/auth/ndev.clouddns.readwrite`.

## Example

Adapt and save the manifest below. Create deployment using `kubectl create -f my-deployment.yaml`.

    apiVersion: extensions/v1beta1

    kind: Deployment

    metadata:

      name: kube-dns-sync

    spec:

      replicas: 1

      template:

        metadata:

          labels:

            app: kube-dns-sync

        spec:

          containers:

          - name: kube-dns-sync

            image: wikiwi/kube-dns-sync:0.1.0

            env:

            - name: KDS_ADDRESS_TYPES

              value: internalip

            - name: KDS_APEX_ADDRESS_TYPE

              value: externalip

            - name: KDS_ZONE_NAME

              value: example.io.

            - name: KDS_PROVIDER

              value: google-clouddns

            - name: KDS_SELECTOR

              value: wikiwi.io/dns-sync!=false

## Flags and Environment Variables

    Usage:

      kube-dns-sync [OPTIONS]

    Application Options:

          --dns-provider=[aws-route53|google-clouddns]             DNS provider [$KDS_PROVIDER]

          --dns-provider-config=                                   Path to config file for configuring DNS provider [$KDS_PROVIDER_CONFIG]

          --zone-name=                                             Zone name, like example.com [$KDS_ZONE_NAME]

          --sync-interval=                                         Interval for syncing with the DNS Provider (default: 60s) [$KDS_INTERVAL]

          --ttl=                                                   TTL value of DNS Records (default: 60) [$KDS_TTL]

          --address-types=                                         Comma list of address types to sync [externalip|internalip|legacyhostip] [$KDS_ADDRESS_TYPES]

          --apex-address-type=[externalip|internalip|legacyhostip] Address type that is synced to the Apex Zone [$KDS_APEX_ADDRESS_TYPE]

          --selector=                                              Node selector e.g. 'cloud.google.com/gke-nodepool=default-pool' [$KDS_SELECTOR]

          --verbose                                                Turn on verbose logging

      -v, --version                                                Show version number

    Help Options:

      -h, --help                                                   Show this help message

## Troubleshooting

- DNS zone is not created by the controller, make sure it exists.

- Make sure you use the correct DNS zone name with a dot at the end.