Step by step how-to for setting up amazon's dynamoDB as backend for storing PHP sessions. Presented at Greece's AWS Usergroup meetup.

1. DynamoDB for PHP Session Storage
25 April 2012
Andreas Chatzakis
@achatzakis on twitter
AWSUG Greece
Not affiliated with, sponsored or endorsed by AWS

2. Sessions in the cloud
Sticky sessions?
Memcache?
MySQL?
Redis?
Enter DynamoDB:
Highly available – Consistently performing
Persistent
AWS SDK now includes drop in PHP session
handler replacement
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3. Create a user
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4. Create a table
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5. Give Permissions
{ "Statement": [
{ "Sid": "Stmt1335183103764",
"Action": [
"dynamodb:BatchGetItem",
"dynamodb:DeleteItem",
"dynamodb:DescribeTable",
"dynamodb:GetItem",
"dynamodb:PutItem",
"dynamodb:Query",
"dynamodb:Scan",
"dynamodb:UpdateItem" ],
"Effect": "Allow",
"Resource": [ "arn:aws:dynamodb:us-east-
1:846544612030:table/php-sessions-test"]
} ] }
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6. Install & Configure SDK
Install the latest version of the SDK on your web server
image - http://aws.amazon.com/sdkforphp/
Update config.inc.php with
the credentials of the user we created in step 1
the default-cache-config parameter (we went for apc, as it is
already running on our instances.)
any other parameters depending on your specific setup details
(the file is well documented)
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7. Instantiate
require_once '/path-to/AWSSDKforPHP/sdk.class.php';
// Instantiate the Amazon DynamoDB client.
$dynamodb = new AmazonDynamoDB();
$dynamodb->set_hostname("https://dynamodb.us-east-1.amazonaws.com");
// Register the DynamoDB Session Handler.
$handler = $dynamodb->register_session_handler(array(
'table_name' => 'php-sessions-test',
'hash_key' => 'id',
'session_lifetime' => 0,
'consistent_reads' => true,
'session_locking' => false,
'max_lock_wait_time' => 15,
'min_lock_retry_utime' => 5000,
'max_lock_retry_utime' => 50000,
));
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8. Update php.ini
session.save_handler = user
auto_prepend_file = /path-to/dynamosessions.php
Restart web server
Test
Snapshot fresh AMI
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9. Considerations
Estimate read/write throughput requirements
Validate post go live
Does your application need locking? By default
php implements pessimistic locking.
The class provided by AWS supports it
Configure it to FALSE if you dont need it (this will
decrease costs and increase performance).
Thorough testing would be required to validate your
selection.
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