custom-domain-name.md

Custom Domain Name

Problem

Using serf-dns with domain name parsed into tags has some limitation:

• cannot use together with name and status
• cannot use regex
• limited to 127 labels, or 63 tags
• limited to 253 characters in full domain name

Solution

Use custom pre-registered domain name with pre-configured serf filters

For example: configure domain name my-custom-dn-1.serf with name ^web-[0-5][0-9], and tags role=web

Use a JSON file to configure custom domain name, like this:

{
	"my-custom-dn-1.serf": {
		"name": "^web-[0-5][0-9]",
		"status": "alive",
		"tags": {
			"role": "web"
		}
	},
	"failed.web.serf": {
		"name": "^web-.*",
		"status": "failed",
		"tags": {
			"role": "web",
			"version": "201605[0-9][0-9].*"
		}
	},
	"us.dc.serf": {
		"tags": {
			"dc": "us-.*"
		}
	}
}

The JSON file above will register 3 domain names:

• my-custom-dn-1.serf: return hosts named range from web-00 to web-59, still alive and tagged role=web
• failed.web.serf: return hosts whose name start with web-, already dead and tagged role=web and version start with 201605
• us.dc.serf: return hosts in US whose tag dc start with us-. Normally, query to this domain name will return hosts with tag dc=us