Documentation: document the -discovery-srv-name flag for configuring service name in DNS discovery.

Documentation/op-guide/clustering.md

@@ -359,6 +359,13 @@ If `_etcd-client-ssl._tcp.example.com` is found, clients will attempt to communi
 
 If etcd is using TLS without a custom certificate authority, the discovery domain (e.g., example.com) must match the SRV record domain (e.g., infra1.example.com). This is to mitigate attacks that forge SRV records to point to a different domain; the domain would have a valid certificate under PKI but be controlled by an unknown third party.
 
+The `-discovery-srv-name` flag additionally configures a suffix to the SRV name that is queried during discovery.
+Use this flag to differentiate between multiple etcd clusters under the same domain.
+For example, if `discovery-srv=example.com` and `-discovery-srv-name=foo` are set, the following DNS SRV queries are made:
+
+* _etcd-server-ssl-foo._tcp.example.com
+* _etcd-server-foo._tcp.example.com
+
 #### Create DNS SRV records
 
 ```

Documentation/op-guide/configuration.md

@@ -155,6 +155,11 @@ To start etcd automatically using custom settings at startup in Linux, using a [
 + default: ""
 + env variable: ETCD_DISCOVERY_SRV
 
+### --discovery-srv-name
++ Suffix to the DNS srv name queried when bootstrapping using DNS.
++ default: ""
++ env variable: ETCD_DISCOVERY_SRV_NAME
+
 ### --discovery-fallback
 + Expected behavior ("exit" or "proxy") when discovery services fails. "proxy" supports v2 API only.
 + default: "proxy"

Documentation/v2/clustering.md

@@ -292,6 +292,13 @@ To help clients discover the etcd cluster, the following DNS SRV records are loo
 
 If `_etcd-client-ssl._tcp.example.com` is found, clients will attempt to communicate with the etcd cluster over SSL.
 
+The `-discovery-srv-name` flag additionally configures a suffix to the SRV name that is queried during discovery.
+Use this flag to differentiate between multiple etcd clusters under the same domain.
+For example, if `discovery-srv=example.com` and `-discovery-srv-name=foo` are set, the following DNS SRV queries are made:
+
+* _etcd-server-ssl-foo._tcp.example.com
+* _etcd-server-foo._tcp.example.com
+
 #### Create DNS SRV records
 
 ```

Documentation/v2/configuration.md

@@ -127,6 +127,11 @@ To start etcd automatically using custom settings at startup in Linux, using a [
 + default: none
 + env variable: ETCD_DISCOVERY_SRV
 
+### --discovery-srv-name
++ Suffix to the DNS srv name queried when bootstrapping using DNS.
++ default: none
++ env variable: ETCD_DISCOVERY_SRV_NAME
+
 ### --discovery-fallback
 + Expected behavior ("exit" or "proxy") when discovery services fails.
 + default: "proxy"