switch to ReplicationGroup for multi AZ support

Author: mattbucci

README.md

@@ -1 +1,34 @@
 # mu-elasticache
+
+Mu-elasticache is an extension [for the devops tool mu](https://github.com/stelligent/mu) 
+
+This extension automatically creates an elasticache redis cluster in all of
+your specified environments
+
+## Using this Extension
+
+copy these files into your project repo, I like to place these extensions under
+the folder "mu", so you would create a new directory called mu/elasticache
+to hold these files
+
+then place the following at the bottom of your mu.yml file
+```
+extensions:
+    - url: mu/elasticache
+```
+
+This is all you need to do to get started.
+
+The following environmental variables can be passed to your application 
+via mu.yml
+
+```
+environment:
+  REDIS_HOST: ${ElasticacheCluster.PrimaryEndPoint.Address}
+  REDIS_PORT: ${ElasticacheCluster.PrimaryEndPoint.Port}
+```
+
+The following parameters are configurable
+NumCacheNodes (default is 2 for Multi AZ failover)
+CacheNodeType (default is cache.t2.micro)
+AutomaticFailoverEnabled (default is true)

service-ecs.yml

@@ -2,11 +2,11 @@ Parameters:
   NumCacheNodes:
     Type: String
     Description: Number of cache nodes
-    Default: 1
+    Default: 2
   CacheNodeType:
     Type: String
     Description: The compute and memory capacity of the node(s) in the Redis Cluster
-    Default: "cache.m3.medium"
+    Default: "cache.t2.micro"
     AllowedValues:
       - cache.t2.micro
       - cache.t2.small
@@ -43,6 +43,10 @@ Parameters:
       - cache.r3.2xlarge
       - cache.r3.4xlarge
       - cache.r3.8xlarge
+  AutomaticFailoverEnabled:
+    Type: String
+    Description: Indicates whether Multi-AZ is enabled. When Multi-AZ is enabled, a read-only replica is automatically promoted to a read-write primary cluster if the existing primary cluster fails.  
+    Default: "true"
 
 Resources:
   ElasticacheSubnetGroup:
@@ -72,15 +76,31 @@ Resources:
               Ref: ServiceSecurityGroup
 
   ElasticacheCluster:
-    Type: "AWS::ElastiCache::CacheCluster"
+    Type: "AWS::ElastiCache::ReplicationGroup"
     Properties:
       Engine: "redis"
       CacheNodeType:
         Ref: CacheNodeType
-      NumCacheNodes:
+      NumCacheClusters:
         Ref: NumCacheNodes
       CacheSubnetGroupName:
         Ref: ElasticacheSubnetGroup
-      VpcSecurityGroupIds:
+      AutomaticFailoverEnabled:
+        Ref: AutomaticFailoverEnabled
+      ReplicationGroupDescription:
+        Fn::Sub: ${Namespace}-${ServiceName}-${EnvironmentName}-cache
+      SecurityGroupIds:
         - Fn::ImportValue:
             Ref: ServiceSecurityGroup
+
+Outputs:
+  ElasticacheClusterEndpointAddress:
+    Description: "Elastic Cache Cluster Endpoint Address"
+    Value: 
+      Fn::Sub:
+        ${ElasticacheCluster.PrimaryEndPoint.Address}
+  ElasticacheClusterEndpointPort:
+    Description: "Elastic Cache Cluster Endpoint Port"
+    Value: 
+      Fn::Sub:
+        ${ElasticacheCluster.PrimaryEndPoint.Port}