Using Auto Discovery

To begin using Auto Discovery with ElastiCache for Memcached, follow these steps:

• Obtain the Configuration Endpoint

• Download the ElastiCache Cluster Client

• Modify Your Application Program

Obtain the Configuration Endpoint

To connect to a cluster, client programs must know the cluster configuration endpoint. See the topic Finding a Cluster's Endpoints (Console) (Memcached)

You can also use the aws elasticache describe-cache-clusters command with the --show-cache-node-info parameter:

Whatever method you use to find the cluster's endpoints, the configuration endpoint will always have .cfg in its address.

Example Finding endpoints using the AWS CLI for ElastiCache

For Linux, macOS, or Unix:

aws elasticache describe-cache-clusters \
    --cache-cluster-id mycluster \
    --show-cache-node-info

For Windows:

aws elasticache describe-cache-clusters ^
    --cache-cluster-id mycluster ^
    --show-cache-node-info

This operation produces output similar to the following (JSON format):

{
    "CacheClusters": [
        {
            "Engine": "memcached", 
            "CacheNodes": [
                {
                    "CacheNodeId": "0001", 
                    "Endpoint": {
                        "Port": 11211, 
                        "Address": "mycluster.fnjyzo.cfg.0001.use1.cache.amazonaws.com"
                    }, 
                    "CacheNodeStatus": "available", 
                    "ParameterGroupStatus": "in-sync", 
                    "CacheNodeCreateTime": "2016-10-12T21:39:28.001Z", 
                    "CustomerAvailabilityZone": "us-east-1e"
                }, 
                {
                    "CacheNodeId": "0002", 
                    "Endpoint": {
                        "Port": 11211, 
                        "Address": "mycluster.fnjyzo.cfg.0002.use1.cache.amazonaws.com"
                    }, 
                    "CacheNodeStatus": "available", 
                    "ParameterGroupStatus": "in-sync", 
                    "CacheNodeCreateTime": "2016-10-12T21:39:28.001Z", 
                    "CustomerAvailabilityZone": "us-east-1a"
                }
            ], 
            "CacheParameterGroup": {
                "CacheNodeIdsToReboot": [], 
                "CacheParameterGroupName": "default.memcached1.4", 
                "ParameterApplyStatus": "in-sync"
            }, 
            "CacheClusterId": "mycluster", 
            "PreferredAvailabilityZone": "Multiple", 
            "ConfigurationEndpoint": {
                "Port": 11211, 
                "Address": "mycluster.fnjyzo.cfg.use1.cache.amazonaws.com"
            }, 
            "CacheSecurityGroups": [], 
            "CacheClusterCreateTime": "2016-10-12T21:39:28.001Z", 
            "AutoMinorVersionUpgrade": true, 
            "CacheClusterStatus": "available", 
            "NumCacheNodes": 2, 
            "ClientDownloadLandingPage": "https://console.aws.amazon.com/elasticache/home#client-download:", 
            "CacheSubnetGroupName": "default", 
            "EngineVersion": "1.4.24", 
            "PendingModifiedValues": {}, 
            "PreferredMaintenanceWindow": "sat:06:00-sat:07:00", 
            "CacheNodeType": "cache.r3.large"
        }
    ]
}

Download the ElastiCache Cluster Client

To take advantage of Auto Discovery, client programs must use the ElastiCache Cluster Client. The ElastiCache Cluster Client is available for Java, PHP, and .NET and contains all of the necessary logic for discovering and connecting to all of your cache nodes.

To download the ElastiCache Cluster Client

1. Sign in to the AWS Management Console and open the ElastiCache console at https://console.aws.amazon.com/elasticache/.

2. From the ElastiCache console, choose ElastiCache Cluster Client then choose Download.

The source code for the ElastiCache Cluster Client for Java is available at https://github.com/amazonwebservices/aws-elasticache-cluster-client-memcached-for-java. This library is based on the popular Spymemcached client. The ElastiCache Cluster Client is released under the Amazon Software License https://aws.amazon.com/asl. You are free to modify the source code as you see fit. You can even incorporate the code into other open source Memcached libraries, or into your own client code.

Note

To use the ElastiCache Cluster Client for PHP, you will first need to install it on your Amazon EC2 instance. For more information, see Installing the ElastiCache cluster client for PHP.

For a TLS supported client download the binary with PHP version 7.4 or higher.

To use the ElastiCache Cluster Client for .NET, you will first need to install it on your Amazon EC2 instance. For more information, see Installing the ElastiCache cluster client for .NET.

Modify Your Application Program

Modify your application program so that it uses Auto Discovery. The following sections show how to use the ElastiCache Cluster Client for Java, PHP, and .NET.

Important

When specifying the cluster's configuration endpoint, be sure that the endpoint has ".cfg" in its address as shown here. Do not use a CNAME or an endpoint without ".cfg" in it.

"mycluster.fnjyzo.cfg.use1.cache.amazonaws.com";

Failure to explicitly specify the cluster's configuration endpoint results in configuring to a specific node.