doc: add doc for initial-cluster-token

Documentation/0.5/clustering.md

@@ -25,16 +25,19 @@ ETCD_INITIAL_CLUSTER_STATE=new
 	-initial-cluster-state new
 ```
 
+If you are spinning up multiple clusters (or creating and destroying a single cluster) with same configuration for testing purpose, it is highly recommended that you specify a unique `initial-cluster-token` for the different clusters. 
+By doing this, etcd can generate unique cluster IDs and member IDs for the clusters even if they otherwise have the exact same configuration. This can protect you from cross-cluster-interaction, which might corrupt your clusters.
+
 On each machine you would start etcd with these flags:
 
 ```
-$ etcd -name infra0 -initial-advertise-peer-urls https://10.0.1.10:2379 \
+$ etcd -name infra0 -initial-advertise-peer-urls https://10.0.1.10:2379 initial-cluster-token etcd-cluster-1\
 	-initial-cluster infra0=http://10.0.1.10:2379,infra1=http://10.0.1.11:2379,infra2=http://10.0.1.12:2379 \
 	-initial-cluster-state new
-$ etcd -name infra1 -initial-advertise-peer-urls https://10.0.1.11:2379 \
+$ etcd -name infra1 -initial-advertise-peer-urls https://10.0.1.11:2379 initial-cluster-token etcd-cluster-1\
 	-initial-cluster infra0=http://10.0.1.10:2379,infra1=http://10.0.1.11:2379,infra2=http://10.0.1.12:2379 \
 	-initial-cluster-state new
-$ etcd -name infra2 -initial-advertise-peer-urls https://10.0.1.12:2379 \
+$ etcd -name infra2 -initial-advertise-peer-urls https://10.0.1.12:2379 initial-cluster-token etcd-cluster-1\
 	-initial-cluster infra0=http://10.0.1.10:2379,infra1=http://10.0.1.11:2379,infra2=http://10.0.1.12:2379 \
 	-initial-cluster-state new
 ```

Procfile

@@ -1,5 +1,5 @@
 # Use goreman to run `go get github.com/mattn/goreman`
-etcd1: bin/etcd -name node1 -listen-client-urls http://127.0.0.1:4001 -advertise-client-urls http://127.0.0.1:4001 -listen-peer-urls http://127.0.0.1:7001 -initial-advertise-peer-urls http://127.0.0.1:7001 -initial-cluster 'node1=http://localhost:7001,node2=http://localhost:7002,node3=http://localhost:7003' -initial-cluster-state new
-etcd2: bin/etcd -name node2 -listen-client-urls http://127.0.0.1:4002 -advertise-client-urls http://127.0.0.1:4002 -listen-peer-urls http://127.0.0.1:7002 -initial-advertise-peer-urls http://127.0.0.1:7002 -initial-cluster 'node1=http://localhost:7001,node2=http://localhost:7002,node3=http://localhost:7003' -initial-cluster-state new
-etcd3: bin/etcd -name node3 -listen-client-urls http://127.0.0.1:4003 -advertise-client-urls http://127.0.0.1:4003 -listen-peer-urls http://127.0.0.1:7003 -initial-advertise-peer-urls http://127.0.0.1:7003 -initial-cluster 'node1=http://localhost:7001,node2=http://localhost:7002,node3=http://localhost:7003' -initial-cluster-state new
+etcd1: bin/etcd -name node1 -listen-client-urls http://127.0.0.1:4001 -advertise-client-urls http://127.0.0.1:4001 -listen-peer-urls http://127.0.0.1:7001 -initial-advertise-peer-urls http://127.0.0.1:7001 -initial-cluster-token etcd-cluster-1 -initial-cluster 'node1=http://localhost:7001,node2=http://localhost:7002,node3=http://localhost:7003' -initial-cluster-state new
+etcd2: bin/etcd -name node2 -listen-client-urls http://127.0.0.1:4002 -advertise-client-urls http://127.0.0.1:4002 -listen-peer-urls http://127.0.0.1:7002 -initial-advertise-peer-urls http://127.0.0.1:7002 -initial-cluster-token etcd-cluster-1 -initial-cluster 'node1=http://localhost:7001,node2=http://localhost:7002,node3=http://localhost:7003' -initial-cluster-state new
+etcd3: bin/etcd -name node3 -listen-client-urls http://127.0.0.1:4003 -advertise-client-urls http://127.0.0.1:4003 -listen-peer-urls http://127.0.0.1:7003 -initial-advertise-peer-urls http://127.0.0.1:7003 -initial-cluster-token etcd-cluster-1 -initial-cluster 'node1=http://localhost:7001,node2=http://localhost:7002,node3=http://localhost:7003' -initial-cluster-state new
 proxy: bin/etcd -proxy=on -bind-addr 127.0.0.1:8080 -initial-cluster 'node1=http://localhost:7001,node2=http://localhost:7002,node3=http://localhost:7003'