Iterators iterators iterators!

Managing lots of CloudFormation stacks can be a pain through the AWS Console.¬†Stacks are paginated so you’ll need to keep clicking that “View more stacks” button until you get to the stack you want.

Performing tasks¬†through the AWS PHP SDK makes it a little easier, but you’ll still need to deal with tokens.

Take the following code snippet for example:

[code lang=php]
$client = \Aws\CloudFormation\CloudFormationClient::factory($config);
$stackstatus = array('CREATE_COMPLETE');

// First run
$result = $client->listStacks(array(
'StackStatusFilter' => $stackstatus,
));
$stacks = $result['StackSummaries'];
$token = $result['NextToken'];
foreach ($stacks as $stack) {
echo "$stack[StackName] – $stack[StackStatus]\n";
}

// Subsequent runs
while ($token != '') {
$result = $client->listStacks(array(
'NextToken' => "$token",
'StackStatusFilter' => $stackstatus,
));
$stacks = $result['StackSummaries'];
$token = $result['NextToken'];
foreach ($stacks as $stack) {
echo "$stack[StackName] – $stack[StackStatus]\n";
}
}
[/code]

Just like in the AWS Console, you’ll need to paginate through the entire list through the use of Tokens. The results on the first page will give you a Token, which you reference on a subsequent request to obtain page 2 and so on and so on.

But there is a better way! And that’s through the use of Iterators.

[code lang=php]
$client = \Aws\CloudFormation\CloudFormationClient::factory($config);
$stackstatus = array('CREATE_COMPLETE');

$iterator = $client->getIterator('ListStacks', array(
'StackStatusFilter' => $stackstatus,
));
$stacks = $iterator->toArray();
foreach ($stacks as $stack) {
echo "$stack[StackName]\n";
}
[/code]

Now that’s better! No pagination and no need to deal with tokens.

Iterators work for listing CF stacks, describing instances, pulling stuff out of DynamoDB, and lots of other things.

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