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https://github.com/djmaze/swarmdns
DNS service for Docker swarm mode which always returns the IP(s) of all active swarm nodes
https://github.com/djmaze/swarmdns
Last synced: 27 days ago
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DNS service for Docker swarm mode which always returns the IP(s) of all active swarm nodes
- Host: GitHub
- URL: https://github.com/djmaze/swarmdns
- Owner: djmaze
- License: gpl-3.0
- Created: 2017-07-02T14:44:58.000Z (over 7 years ago)
- Default Branch: master
- Last Pushed: 2024-02-02T12:39:52.000Z (11 months ago)
- Last Synced: 2024-12-08T20:41:31.182Z (about 1 month ago)
- Language: Go
- Homepage: https://hub.docker.com/r/mazzolino/swarmdns/
- Size: 11.7 MB
- Stars: 16
- Watchers: 4
- Forks: 2
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# SwarmDNS
A tiny dockerized DNS service for Docker swarm mode. It always returns the IP(s) of all active swarm nodes.
That makes it easy to host an arbitrary number of swarm services on a subdomain. Just add an `NS` record for the chosen subdomain for _every manager node_ in the swarm.
As the service works on manager nodes only, you should have more than one manager node for fail-safe operation.
## Quickstart
```bash
$ docker service create --name swarmdns \
-p 53:53/udp \
--mount type=bind,source=/var/run/docker.sock,target=/var/run/docker.sock,readonly \
--constraint "node.role == manager" \
mazzolino/swarmdns
--domain swarm.example.com
```
Alternatively, deploy the service stack definition supplied in this repository:
```bash
docker stack deploy --compose-file docker-compose.yml swarmdns
```
### Testing
With a cluster of 3 nodes:
```bash
$ docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS
4mqk9wohilllRkj7zppwie18h swarm3 Ready Active Reachable
hhv80nx8r2jadchRohk4h3pfx * swarm2 Ready Active Reachable
xx4zcnjnr80yletg4pnx00b4n swarm1 Ready Active Leader
```
Here's the output:
```bash
$ dig +short foo.swarm.example.com @
192.168.1.230
192.168.1.231
192.168.1.232
$ dig +short bar.swarm.example.com @
192.168.1.231
192.168.1.232
192.168.1.230
```
## How it works
SwarmDNS will answer requests for `A` records only, and only for names in the domains specified at the commandline. It will always return the IP addresses of __all active nodes__ in the swarm, in random order. (The `AVAILABILITY` column in `docker node ls` shows which nodes are currently `Active`.)
The list of active nodes is refreshed once a minute. The TTL of the returned records is also set to 60 seconds.
### Options
The domains to return results for need to be specified using the `--domain` flag (e.g. `-domain swarm.example.com`).
When given the `--log` flag, every matching request will be logged to STDOUT. Example:
Request: 172.17.0.1 foo.swarm.example.com.
Request: 172.17.0.1 bar.swarm.example.com.
When using `--rate-limit xxx`, the number of simultaneous requests being worked on is limited to `xxx`. That means additional requests being sent in parallel will be delayed.
## Development
### Prerequisites
* Docker
* Docker-Compose
### Building
Just run `docker-compose build`. It builds a docker image `mazzolino/swarmdns` by default.
### Testing
(Only works if your host is a swarm manager node.)
```bash
$ docker-compose up -d
$ dig foo.swarm.example.com @localhost
```
## Credits
This is a fork of [WildDNS](https://github.com/djmaze/wilddns). The code structure was originally adopted from [microdns](https://github.com/fffaraz/microdns). Thanks!