Merge pull request #113 from chaudum/master

extended multicast section in Crate readme

crate/content.md

@@ -4,7 +4,7 @@ Crate is an Elastic SQL Data Store. Distributed by design, Crate makes
 centralized database servers obsolete. Realtime non-blocking SQL engine with
 full blown search. Highly available, massively scalable yet simple to use.
 
-> [Crate](https:/crate.io/)
+[Crate](https:/crate.io/)
 
 %%LOGO%%
 
@@ -41,10 +41,39 @@ For example, setting the heap size:
 
 ## Multicast
 
-Crate uses multicast for node discovery by default. However, Docker does only
-support multicast on the same host. This means that nodes that are started on
-the same host will discover each other automatically, but nodes that are started
-on different hosts need unicast enabled.
-
-You can enable unicast in your custom `crate.yml`. See also: [Using Crate Data
-in a Multi Node Setup](https://crate.io/blog/using-crate-in-multinode-setup/).
+Crate uses multicast for node discovery by default. However, Docker does only support multicast on the same
+host. This means that nodes that are started on the same host will discover each other automatically,
+but nodes that are started on different hosts need unicast enabled.
+
+You can enable unicast in your custom ``crate.yml``.
+See also: [Crate Multi Node Setup](https://crate.io/docs/en/latest/best_practice/multi_node_setup.html).
+
+Due to its architecture, Crate publishes the host it runs on for discovery within the cluster. Since
+the address of the host inside the docker container differs from the actual host the docker image is
+running on, you need to tell Crate to publish the address of the docker host for discovery.
+
+    docker run -d -p 4200:4200 -p 4300:4300 crate crate -Des.network.publish_host=host1.example.com:
+
+If you change the transport port from the default ``4300`` to something else, you also need to pass
+the publish port to Crate.
+
+    docker run -d -p 4200:4200 -p 4321:4300 crate crate -Des.transport.publish_port=4321
+
+### Example Usage in a Multinode Setup
+
+    HOSTS='crate1.example.com:4300,crate2.example.com:4300,crate3.example.com:4300'
+    HOST=crate1.example.com
+    docker run -d \
+        -p 4200:4200 \
+        -p 4300:4300 \
+        --name node1 \
+        --volume /mnt/data:/data \
+        --env CRATE_HEAP_SIZE=8g \
+        crate:latest \
+        crate -Des.cluster.name=cratecluster \
+              -Des.node.name=crate1 \
+              -Des.transport.publish_port=4300 \
+              -Des.network.publish_host=$HOST \
+              -Des.multicast.enabled=false \
+              -Des.discovery.zen.ping.unicast.hosts=$HOSTS \
+              -Des.discovery.zen.minimum_master_nodes=2