Added architecture overview on the VPC level.

Documented some considerations.
zalando · Apr 24, 2015 · bf1697f · bf1697f
1 parent 2e877ab
commit bf1697f
Showing 1 changed file with 48 additions and 3 deletions.
diff --git a/docs/DESIGN.md b/docs/DESIGN.md
@@ -9,6 +9,53 @@ Spilo was designed to be deployed on AWS.
 Architecture: VPC
 =================
 
+	VPC                                                              
+	+---------------------------------------------------------------+
+	|                                                               |
+	|                 etcd                                          |
+	|                   O            DNS Service Record (SRV)       |
+	|         +-----> O   O +-------> _etcd+server._tcp.example.com |
+	|         |        O O<+                                        |
+	|         |        ^   |                                        |
+	|         |        |   |            +-----+                     |
+	|         |        +---------------->     |                     |
+	|         |  +----------------------> DDS |                     |
+	|         |  |         |   +-------->     |                     |
+	|         |  |         |   |        +-----+                     |
+	| +--------------+  +--------------+                            |
+	| |-------v------|  |--v-----------|                            |
+	| ||            ||  ||            ||                            |
+	| ||HA Cluster 1||  ||HA Cluster 2||                            |
+	| ||            ||  ||            ||                            |
+	| |--------------|  |--------------|                            |
+	| +--------------+  +--------------+                            |
+	|                                                               |
+	+---------------------------------------------------------------+
+
+Considerations
+--------------
+When considering what to build we had to determine which problems we want to solve or prevent.
+The following points are important for us:
+
+- automatic failover
+- deploying a new HA-cluster can be done very quickly (< 15 minutes)
+- human interaction for creating a HA-cluster is minimal
+- sane defaults for a HA-cluster (security, configuration, backup)
+
+High Available cluster (HA-cluster)
+-----------------
+A set of machines serving PostgreSQL databases. Its architecture is explained in more detail further on.
+
+etcd
+----
+We were pointed towards etcd in combination with PostgreSQL by compose with their [governor](https://github.com/compose/governor). By using an external service which is specialized in solving the problem of distributed consencus we don't have to write our own. We will use one etcd per environment.
+
+To find out more about etcd: [coreos.com/etcd](https://coreos.com/etcd/)
+
+dds
+---
+A dynamic discovery service could be running which will gather information about the running HA-clusters. To find out which HA-clusters are running it will consult etcd.
+The results of its discovery will also be stored in etcd, so other tools can easily use the discovered information.
 
 
 
@@ -51,10 +98,8 @@ Architecture: PostgreSQL High Available cluster
 
 
 
-etcd
+etcd proxy
 ====
-We were pointed towards etcd in combination with PostgreSQL by compose with their [governor](https://github.com/compose/governor). By using an external service which is specialized in solving the problem of distributed consencus we don't have to write our own.
-
 We assume a Higly Available etcd-cluster to be available for spilo when it is bootstrapped; we will use a etcd-proxy running on localhost to be a bridge between a HA-cluster member and the etcd-cluster.
 
 HAProxy