Caching Application Data Using Redis Labs Memcache

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Note: Redis Labs is a third-party company whose services are not covered by the Google App Engine Service Level Agreement.

You can use Redis Labs Memcached Cloud to cache application data. Memcached Cloud is a fully-managed service offering a variety of options for running Memcached.

Pricing

Redis Labs offers a free tier that provides 30mb of cache storage.

Setting up

To use Redis Labs Memcached Cloud:

1. Sign up for a Redis Labs account.
2. Create a Memcached Bucket using Memcached Cloud. For the lowest latency, create the Memcache bucket in the same region as your app.
3. Edit the bucket and set a username and password.
4. Note the bucket's Endpoint.

Installing a Memcached client library

Because Redis Labs uses SASL authentication, you need to use a Memcached client that supports the binary protocol and SASL authentication.

By default, the PHP runtime includes the memcached extension.

Connecting to Redis Labs Memcache

Configure environment variables in your app.yaml with the Memcached server endpoint, username, and password for your Redis Labs Memcached bucket:

appengine/flexible/memcache/app.yaml

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env_variables:
  # If you are using the App Engine Memcache service (currently in alpha),
  # uncomment this section and comment out the other Memcache variables.
  # USE_GAE_MEMCACHE: 1
  MEMCACHE_SERVER: your-memcache-server
  # If you are using a Memcached server with SASL authentiation enabled,
  # fill in these values with your username and password.
  MEMCACHE_USERNAME: ""
  MEMCACHE_PASSWORD: ""

Use the environment variables in your application code to configure a Memcached client:

appengine/flexible/memcache/app.php

View on GitHub

// $host = 'YOUR_MEMCACHE_HOST';
// $port = 'YOUR_MEMCACHE_PORT';
// $username = 'OPTIONAL_MEMCACHE_USERNAME';
// $password = 'OPTIONAL_MEMCACHE_PASSWORD';
$memcached = new Memcached;
if ($username && $password) {
    $memcached->setOption(Memcached::OPT_BINARY_PROTOCOL, true);
    $memcached->setSaslAuthData($username, $password);
}
if (!$memcached->addServer($host, $port)) {
    throw new Exception("Failed to add server $host:$port");
}

Testing Memcached locally

If you are testing your app locally, you can still connect to your the Redis Labs Memcached bucket. However, you might want to run a local instance of Memcached to avoid interacting with production data.

To run a local Memcached instance, install a Memcached daemon in your OS:

Linux

1. Use the memcached package.

   For Debian and Ubuntu derivatives:

   apt-get install memcached
   

   For Red Hat, CentOS, and Fedora, use yum:

   yum install memcached
   

   For Linux Arch:

   pacman -S memcached
   

2. Run it as a daemon (or check systemd for an automatic startup):

   memcached -d
   

Mac OS X

1. Install Homebrew.

2. Install memcached:

   brew install memcached
   

3. Run it as a daemon:

   memcached -d
   

Windows

1. Build your own memcached. Alternatively, you can download freeware binaries.

2. Run it as a daemon:

   memcached -d