yuanxiao

A flexible DNS server for small facilities.

Overview

The motivation of writing yuanxiao is to cover HA(High Availability) at domain name level. It is built for SREs who want to use DNS to dispatch service at top level.It is designed to be extensible, easy to deploy. Users can build tools on it to adapt their application scenarios.

The DNS records are set to different kind of sources which are tried one after another until one success. Using a combination of several sources with a specific order can achieve multiple purpose.

Installation

To build yuanxiao, you need a working go compiler, then just go-get it:

go get go.papla.net/yuanxiao

Like other golang program, you'll get a single binary ready to run.

Usage

After deploy, first thing to do is to generate a sample configuration file by running:

/path/to/yuanxiao -config.generate > /etc/yuanxiao.conf

You can change the location of config file as your wish. The descriptions for all the options are include in that file.

Source

Source is an abstract database for yuanxiao to query for answers. Three sources are currently supported: plain, etcd, relay.

source: plain

A simple file or a directory of files which have the format of BIND zone file. Hidden files are ignored while parsing.

source: etcd

Use etcd as its backend. Domain names need to be splited into labels and saved in reverse order. The values can be read from a zone file syntax as the plain source. Records are add by using the CREAT command of etcd. For example, we have two domains in etcd, both have a A record:

foo.com.     30 A 1.1.1.1
www.bar.com. 30 A 2.2.2.2

in etcd, they should be saved in this format

curl -s 'http://localhost:2379/v2/keys?recursive=true' | python -m json.tool
{
    "action": "get",
    "node": {
	"createdIndex": 7,
	"dir": true,
	"modifiedIndex": 7,
	"nodes": [
	    {
		"createdIndex": 21,
		"dir": true,
		"key": "/com",
		"modifiedIndex": 21,
		"nodes": [
		    {
			"createdIndex": 21,
			"dir": true,
			"key": "/com/foo",
			"modifiedIndex": 21,
			"nodes": [
			    {
				"createdIndex": 24,
				"key": "/com/foo/21",
				"modifiedIndex": 24,
				"value": " 30 A 1.1.1.1"
			    }
			]
		    },
		    {
			"createdIndex": 22,
			"dir": true,
			"key": "/com/bar",
			"modifiedIndex": 22,
			"nodes": [
			    {
				"createdIndex": 22,
				"dir": true,
				"key": "/com/bar/www",
				"modifiedIndex": 22,
				"nodes": [
				    {
					"createdIndex": 23,
					"key": "/com/bar/www/22",
					"modifiedIndex": 23,
					"value": " 30 A 2.2.2.2"
				    }
				]
			    }
			]
		    }
		]
	    }
	]
    }
}

source: relay

A proxy to relay the request to one or several upstream recursive servers.