Merge pull request #1973 from kelseyhightower/dns-bootstrap-docs

docs: add dns bootstrap guide

Documentation/2.0/dns_bootstrap.md

@@ -0,0 +1,99 @@
+# DNS Bootstrap
+
+DNS SRV records can be used as a discovery mechanism for bootstrapping an etcd cluster, or configuring an etcd node running in proxy mode.
+
+### Create DNS SRV records
+
+```
+$ dig +noall +answer SRV _etcd-server._tcp.example.com
+_etcd-server._tcp.example.com. 300 IN	SRV	0 0 2380 infra0.example.com.
+_etcd-server._tcp.example.com. 300 IN	SRV	0 0 2380 infra1.example.com.
+_etcd-server._tcp.example.com. 300 IN	SRV	0 0 2380 infra2.example.com.
+```
+
+```
+$ dig +noall +answer infra0.example.com infra1.example.com infra2.example.com
+infra0.example.com.	300	IN	A	10.0.1.10
+infra1.example.com.	300	IN	A	10.0.1.11
+infra2.example.com.	300	IN	A	10.0.1.12
+```
+
+## Bootstrap the etcd cluster using DNS
+
+etcd cluster memebers can listen on domain names or IP address, the bootstrap process will resolve DNS A records. The following examples will set up a 3 node etcd cluster listening on domain names:
+
+```
+$ etcd -name infra0 \
+-discovery-srv example.com \
+-initial-advertise-peer-urls http://infra0.example.com:2380 \
+-initial-cluster-token etcd-cluster-1 \
+-initial-cluster-state new \
+-advertise-client-urls http://infra0.example.com:2379 \
+-listen-client-urls http://infra0.example.com:2379 \
+-listen-peer-urls http://infra0.example.com:2380
+```
+
+```
+$ etcd -name infra1 \
+-discovery-srv example.com \
+-initial-advertise-peer-urls http://infra1.example.com:2380 \
+-initial-cluster-token etcd-cluster-1 \
+-initial-cluster-state new \
+-advertise-client-urls http://infra1.example.com:2379 \
+-listen-client-urls http://infra1.example.com:2379 \
+-listen-peer-urls http://infra1.example.com:2380
+```
+
+```
+$ etcd -name infra2 \
+-discovery-srv example.com \
+-initial-advertise-peer-urls http://infra2.example.com:2380 \
+-initial-cluster-token etcd-cluster-1 \
+-initial-cluster-state new \
+-advertise-client-urls http://infra2.example.com:2379 \
+-listen-client-urls http://infra2.example.com:2379 \
+-listen-peer-urls http://infra2.example.com:2380
+```
+
+You can also bootstrap the cluster using IP addresses instead of domain names:
+
+```
+$ etcd -name infra0 \
+-discovery-srv example.com \
+-initial-advertise-peer-urls http://10.0.1.10:2380 \
+-initial-cluster-token etcd-cluster-1 \
+-initial-cluster-state new \
+-advertise-client-urls http://10.0.1.10:2379 \
+-listen-client-urls http://10.0.1.10:2379 \
+-listen-peer-urls http://10.0.1.10:2380
+```
+
+```
+$ etcd -name infra1 \
+-discovery-srv example.com \
+-initial-advertise-peer-urls http://10.0.1.11:2380 \
+-initial-cluster-token etcd-cluster-1 \
+-initial-cluster-state new \
+-advertise-client-urls http://10.0.1.11:2379 \
+-listen-client-urls http://10.0.1.11:2379 \
+-listen-peer-urls http://10.0.1.11:2380
+```
+
+```
+$ etcd -name infra2 \
+-discovery-srv example.com \
+-initial-advertise-peer-urls http://10.0.1.12:2380 \
+-initial-cluster-token etcd-cluster-1 \
+-initial-cluster-state new \
+-advertise-client-urls http://10.0.1.12:2379 \
+-listen-client-urls http://10.0.1.12:2379 \
+-listen-peer-urls http://10.0.1.12:2380
+```
+
+### etcd proxy configuration
+
+DNS SRV records can also be used to configure the list of peers for an etcd server running in proxy mode:
+
+```
+$ etcd --proxy on -discovery-srv example.com
+```