This page contains information about using the Redis service in Handel. This service provides a Redis cluster via the ElastiCache service.
No Cluster Mode Support¶
This service currently does not support using Redis in cluster mode. It does support replication groups with a primary node and 1 or more read replicas, but it doesn’t yet support Redis’ cluster mode sharding.
No Restoration From Snapshot¶
This service currently doesn’t allow you to launch a cluster from a previous cluster snapshot.
|type||string||Yes||This must always be redis for this service type.|
|instance_type||string||Yes||The size of each Redis instance in your cluster. See Choosing Your Node Size for more details.|
|description||string||No||Parameter group.||The redis group description.|
|maintenance_window||string||No||The weekly time range (in UTC) during which ElastiCache may peform maintenance on the node group. For example, you can specify Sun:05:00-Tue:09:00.|
|redis_version||string||Yes||The version of Redis to run. See Comparing Redis Versions for a list of available versions.|
|read_replicas||number||No||0||The number of read replicas you want to provision. Allowed values: 0-5.|
|snapshot_window||string||No||The daily time range (in UTC) during which ElastiCache will begin taking a daily snapshot of your node group. For example, you can specify 05:00-09:00. This feature is not available on the t2 and t1 instance types.|
|cache_parameters||Map<string,string>||No||Any cache parameters you wish for your Redis cluster. See Redis Specific Parameters for the list of parameters you can provide.|
|tags||Tags||No||Any tags you wish to apply to this Redis cluster.|
If you use read replicas, be aware that it will greatly increase your cost. Each read replica you use adds the full cost of another Redis node.
For example, if you have a single cache.m4.large Redis instance with no read replicas, it will cost about $112/month.
If you have that same cache.m4.large type, but with 1 read replica, it will cost you double at about $224/month since you are being charged for two full Redis instances.
Taken to its extreme, a cache.m4.large with 5 read replicas will cost about $673/month. Be careful to calculate how much this service will cost you if you are using read replicas
Example Handel File¶
version: 1 name: my-redis-cluster environments: dev: cache: type: redis instance_type: cache.m3.medium redis_version: 3.2.4 read_replicas: 1 cache_parameters: activerehashing: 'no' tags: mytag: myvalue
Depending on this service¶
The Redis service outputs the following environment variables:
|<ENV_PREFIX>_ADDRESS||The DNS name of the primary Redis node|
|<ENV_PREFIX>_PORT||The port on which the primary Redis node is listening.|
The <ENV_PREFIX> is a consistent prefix applied to all information injected for service dependencies. See Environment Variable Prefix for information about the structure of this prefix.
Events produced by this service¶
The Redis service does not produce events for other Handel services to consume.
Events consumed by this service¶
The Redis service does not consume events from other Handel services.