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Amazon ElastiCache
User Guide (API Version 2015-02-02)

Connecting to Nodes

In order for you to use your cache, your application must connect to the nodes in the cluster. This section covers how to connect to nodes in Memcached and Redis clusters.

This section assumes that you've created an Amazon EC2 instance and can connect to it. For instructions on how to do this, go to the Amazon EC2 Getting Started Guide.

An Amazon EC2 instance can connect to a cluster node only if you have authorized it to do so. For more information, see Step 4: Authorize Access.

Connecting to Memcached Nodes

Before attempting to connect to your Memcached cluster, you must have the endpoints for the nodes. To find the endpoints, see:

In the following example, you use the telnet utility to connect to a node that is running Memcached.

Note

For more information about Memcached and available Memcached commands, see the Memcached website.

To connect to a node using telnet

  1. Connect to your Amazon EC2 instance by using the connection utility of your choice.

    Note

    For instructions on how to connect to an Amazon EC2 instance, see the Amazon EC2 Getting Started Guide.

  2. Download and install the telnet utility on your Amazon EC2 instance. At the command prompt of your Amazon EC2 instance, type the following command and type y at the command prompt.

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    sudo yum install telnet

    Output similar to the following appears.

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    Loaded plugins: priorities, security, update-motd, upgrade-helper Setting up Install Process Resolving Dependencies --> Running transaction check ...(output omitted)... Total download size: 63 k Installed size: 109 k Is this ok [y/N]: y Downloading Packages: telnet-0.17-47.7.amzn1.x86_64.rpm | 63 kB 00:00 ...(output omitted)... Complete!
  3. At the command prompt of your Amazon EC2 instance, type the following command, substituting the endpoint of your node for the one shown in this example.

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    telnet mycachecluster.eaogs8.0001.usw2.cache.amazonaws.com 11211

    Output similar to the following appears.

    Trying 128.0.0.1...
    Connected to mycachecluster.eaogs8.0001.usw2.cache.amazonaws.com.
    Escape character is '^]'.
    >
  4. Test the connection by running Memcached commands.

    You are now connected to a node, and you can run Memcached commands. The following is an example.

    set a 0 0 5      // Set key "a" with no expiration and 5 byte value
    hello            // Set value as "hello"
    STORED
    get a            // Get value for key "a"
    VALUE a 0 5
    hello
    END
    get b            // Get value for key "b" results in miss
    END
    >

Connecting to Redis Nodes

Before attempting to connect to the nodes in your Redis cluster, you must have the endpoints for the nodes. To find the endpoints, see:

In the following example, you use the redis-cli utility to connect to a cluster that is running Redis.

Note

For more information about Redis and available Redis commands, see the http://redis.io/commands webpage.

To connect to a Redis cluster using the redis-cli

  1. Connect to your Amazon EC2 instance using the connection utility of your choice.

    Note

    For instructions on how to connect to an Amazon EC2 instance, see the Amazon EC2 Getting Started Guide.

  2. Before you can build redis-cli, you will need to download and install the GNU Compiler Collection (gcc). At the command prompt of your EC2 instance, type the following command and type y at the confirmation prompt.

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    sudo yum install gcc

    Output similar to the following appears.

    Loaded plugins: priorities, security, update-motd, upgrade-helper
    Setting up Install Process
    Resolving Dependencies
    --> Running transaction check
    
    ...(output omitted)...
    
    Total download size: 27 M
    Installed size: 53 M
    Is this ok [y/N]: y
    Downloading Packages:
    (1/11): binutils-2.22.52.0.1-10.36.amzn1.x86_64.rpm      | 5.2 MB     00:00     
    (2/11): cpp46-4.6.3-2.67.amzn1.x86_64.rpm                | 4.8 MB     00:00     
    (3/11): gcc-4.6.3-3.10.amzn1.noarch.rpm                  | 2.8 kB     00:00     
    
    ...(output omitted)...
    
    Complete!
    
    				
  3. Download and compile the redis-cli utility. This utility is included in the Redis software distribution. At the command prompt of your EC2 instance, type the following commands:

    Note

    For Ubuntu systems, prior to running make, run make distclean.

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    wget http://download.redis.io/redis-stable.tar.gz tar xvzf redis-stable.tar.gz cd redis-stable make distclean // ubuntu systems only make
  4. At the command prompt of your EC2 instance, type the following command, substituting the endpoint of your cluster for the one shown in this example.

    Repeat this step for each node in your cluster that you want to connect to.

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    src/redis-cli -c -h mycachecluster.eaogs8.0001.usw2.cache.amazonaws.com -p 6379

    A Redis command prompt similar to the following appears.

    redis mycachecluster.eaogs8.0001.usw2.cache.amazonaws.com 6379>
  5. Test the connection by running Redis commands.

    You are now connected to the cluster and can run Redis commands. The following are some example commands with their Redis responses.

    set a "hello"          // Set key "a" with a string value and no expiration
    OK
    get a                  // Get value for key "a"
    "hello"
    get b                  // Get value for key "b" results in miss
    (nil)				
    set b "Good-bye" EX 5  // Set key "b" with a string value and a 5 second expiration
    get b
    "Good-bye"
                           // wait 5 seconds
    get b
    (nil)                  // key has expired, nothing returned
    quit                   // Exit from redis-cli

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