Merge pull request #3 from zumba/alias-strategy

Add an alias strategy for primary index.

README.md

@@ -46,7 +46,7 @@ $client->search([
 <?php
 
 $client = new \Elasticsearch\Client();
-$indexRotator = new IndexRotator($client, 'pizza_shops');
+$indexRotator = new \Zumba\ElasticsearchRotator\IndexRotator($client, 'pizza_shops');
 // Build your index here
 $newlyBuiltIndexName = 'my_new_built_index_name';
 $indexRotator->copyPrimaryIndexToSecondary();
@@ -97,3 +97,36 @@ class MySearchIndex {
 
 }
 ```
+
+## Using Strategies
+
+You can now customize the strategy of getting/setting the primary index. By default, the `ConfigurationStrategy` is employed,
+however we have also included an `AliasStrategy`. The main difference is when `setPrimaryIndex` is called, instead of creating an entry
+in the configuration index, it adds an alias (specified by `alias_name` option) on the specified index and deletes all other aliases
+for the old primary indices (specified by `index_pattern`).
+
+#### Using the `AliasStrategy`
+
+```php
+<?php
+
+$client = new \Elasticsearch\Client();
+$indexRotator = new \Zumba\ElasticsearchRotator\IndexRotator($client, 'pizza_shops');
+$aliasStrategy = $indexRotator->strategyFactory(IndexRotator::STRATEGY_ALIAS, [
+	'alias_name' => 'pizza_shops',
+	'index_pattern' => 'pizza_shops_*'
+]);
+// Build your index here
+$newlyBuiltIndexName = 'pizza_shops_1234102874';
+$indexRotator->copyPrimaryIndexToSecondary();
+$indexRotator->setPrimaryIndex($newlyBuiltIndexName);
+
+// Now that the alias is set, you can search on that alias instead of having to call `getPrimaryIndex`.
+$client->search([
+	'index' => 'pizza_shops',
+	'type' => 'shop',
+	'body' => [] //...
+])
+```
+
+Since the alias (`pizza_shops`) is mapped to the primary index (`pizza_shops_1234102874`), you can use the alias directly in your client application rather than having to call `getPrimaryIndex()` on the `IndexRotator`. That being said, calling `getPrimaryIndex` won't return the alias, but rather the index that it is aliasing. The secondary entries in the configuration index are still used and reference the actual index names, since the alias can be updated at any time and there wouldn't be a reference to remove the old one.

phpunit.xml

@@ -14,4 +14,9 @@
 			<directory suffix="Test.php">./tests</directory>
 		</testsuite>
 	</testsuites>
+	<filter>
+		<whitelist addUncoveredFilesFromWhitelist="true">
+			<directory>./src</directory>
+		</whitelist>
+	</filter>
 </phpunit>

src/Common/PrimaryIndexStrategy.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace Zumba\ElasticsearchRotator\Common;
+
+use Elasticsearch\Client;
+use Psr\Log\LoggerInterface;
+
+interface PrimaryIndexStrategy
+{
+	/**
+	 * Constructor.
+	 *
+	 * @param \Elasticsearch\Client $engine
+	 * @param \Psr\Log\LoggerInterface $logger
+	 * @param array $options Options specific to this strategy
+	 */
+	public function __construct(Client $engine, LoggerInterface $logger, array $options = []);
+
+	/**
+	 * Get the primary index name for this configuration.
+	 *
+	 * @return string
+	 * @throws \ElasticsearchRotator\Exceptions\MissingPrimaryException
+	 */
+	public function getPrimaryIndex();
+
+	/**
+	 * Get the primary index name for this configuration.
+	 *
+	 * @return string
+	 * @throws \ElasticsearchRotator\Exceptions\MissingPrimaryException
+	 */
+	public function setPrimaryIndex($name);
+}

src/ConfigurationIndex.php

@@ -0,0 +1,81 @@
+<?php
+
+namespace Zumba\ElasticsearchRotator;
+
+use Elasticsearch\Client;
+use Psr\Log\LoggerInterface;
+
+class ConfigurationIndex
+{
+	const INDEX_NAME_CONFIG = '.%s_configuration';
+	const TYPE_CONFIGURATION = 'configuration';
+	const PRIMARY_ID = 'primary';
+
+	/**
+	 * Constructor.
+	 *
+	 * @param \Elasticsearch\Client $engine [description]
+	 * @param \Psr\Log\LoggerInterface $logger [description]
+	 * @param string $prefix
+	 */
+	public function __construct(Client $engine, LoggerInterface $logger, $prefix)
+	{
+		$this->engine = $engine;
+		$this->logger = $logger;
+		$this->configurationIndexName = sprintf(ConfigurationIndex::INDEX_NAME_CONFIG, $prefix);
+	}
+
+	/**
+	 * Determines if the configured configuration index is available.
+	 *
+	 * @return boolean
+	 */
+	public function isConfigurationIndexAvailable()
+	{
+		return $this->engine->indices()->exists(['index' => $this->configurationIndexName]);
+	}
+
+	/**
+	 * Create the index needed to store the primary index name.
+	 *
+	 * @return void
+	 */
+	public function createCurrentIndexConfiguration()
+	{
+		if ($this->isConfigurationIndexAvailable()) {
+			return;
+		}
+		$this->engine->indices()->create([
+			'index' => $this->configurationIndexName,
+			'body' => static::$elasticSearchConfigurationMapping
+		]);
+		$this->logger->debug('Configuration index created.', [
+			'index' => $this->configurationIndexName
+		]);
+	}
+
+	/**
+	 * Delete an entry from the configuration index.
+	 *
+	 * @param string $id
+	 * @return array
+	 */
+	public function deleteConfigurationEntry($id)
+	{
+		return $this->engine->delete([
+			'index' => $this->configurationIndexName,
+			'type' => static::TYPE_CONFIGURATION,
+			'id' => $id
+		]);
+	}
+
+	/**
+	 * String representation of this class is the index name.
+	 *
+	 * @return string
+	 */
+	public function __toString()
+	{
+		return $this->configurationIndexName;
+	}
+}

src/IndexRotator.php

@@ -5,16 +5,17 @@
 use Psr\Log\LoggerInterface;
 use Psr\Log\NullLogger;
 use Elasticsearch\Client;
+use Zumba\ElasticsearchRotator\Common\PrimaryIndexStrategy;
 
 class IndexRotator
 {
-	const INDEX_NAME_CONFIG = '.%s_configuration';
-	const TYPE_CONFIGURATION = 'configuration';
 	const SECONDARY_NAME_ONLY = 0;
 	const SECONDARY_INCLUDE_ID = 1;
-	const PRIMARY_ID = 'primary';
 	const RETRY_TIME_COPY = 500000;
 	const MAX_RETRY_COUNT = 5;
+	const STRATEGY_CONFIGURATION = 'Zumba\ElasticsearchRotator\Strategy\ConfigurationStrategy';
+	const STRATEGY_ALIAS = 'Zumba\ElasticsearchRotator\Strategy\AliasStrategy';
+	const DEFAULT_PRIMARY_INDEX_STRATEGY = self::STRATEGY_CONFIGURATION;
 
 	/**
 	 * Elasticsearch client instance.
@@ -24,18 +25,18 @@ class IndexRotator
 	private $engine;
 
 	/**
-	 * Prefix identifier for this index.
+	 * Configuration index name for this index.
 	 *
-	 * @var string
+	 * @var \Zumba\ElasticsearchRotator\ConfigurationIndex
 	 */
-	private $prefix;
+	private $configurationIndex;
 
 	/**
-	 * Configuration index name for this index.
+	 * Strategy to employ when working on primary index.
 	 *
-	 * @var string
+	 * @var \Zumba\ElasticsearchRotator\Common\PrimaryIndexStrategy
 	 */
-	private $configurationIndexName;
+	private $primaryIndexStrategy;
 
 	/**
 	 * Mapping for configuration index.
@@ -62,13 +63,31 @@ class IndexRotator
 	public function __construct(\Elasticsearch\Client $engine, $prefix, LoggerInterface $logger = null)
 	{
 		$this->engine = $engine;
-		$this->prefix = $prefix;
-		if ($logger !== null) {
-			$this->logger = $logger;
-		} else {
-			$this->logger = new NullLogger();
-		}
-		$this->configurationIndexName = sprintf(static::INDEX_NAME_CONFIG, $this->prefix);
+		$this->logger = $logger ?: new NullLogger();
+		$this->configurationIndex = new ConfigurationIndex($this->engine, $this->logger, $prefix);
+		$this->setPrimaryIndexStrategy($this->strategyFactory(static::DEFAULT_PRIMARY_INDEX_STRATEGY, [
+			'configuration_index' => $this->configurationIndex
+		]));
+	}
+
+	/**
+	 * Instantiate a specific strategy.
+	 *
+	 * @param string $strategyClass Fully qualified class name for a strategy.
+	 * @param array $options Options specific to the strategy
+	 * @return \Zumba\ElasticsearchRotator\Common\PrimaryIndexStrategy
+	 */
+	public function strategyFactory($strategyClass, array $options = []) {
+		return new $strategyClass($this->engine, $this->logger, $options);
+	}
+
+	/**
+	 * Set the primary index strategy.
+	 *
+	 * @param \Zumba\ElasticsearchRotator\Common\PrimaryIndexStrategy $strategy
+	 */
+	public function setPrimaryIndexStrategy(PrimaryIndexStrategy $strategy) {
+		$this->primaryIndexStrategy = $strategy;
 	}
 
 	/**
@@ -79,23 +98,8 @@ public function __construct(\Elasticsearch\Client $engine, $prefix, LoggerInterf
 	 */
 	public function getPrimaryIndex()
 	{
-		if (!$this->engine->indices()->exists(['index' => $this->configurationIndexName])) {
-			$this->logger->error('Primary index configuration index not available.');
-			throw new Exception\MissingPrimaryIndex('Primary index configuration index not available.');
-		}
-		$primaryPayload = [
-			'index' => $this->configurationIndexName,
-			'type' => static::TYPE_CONFIGURATION,
-			'id' => static::PRIMARY_ID,
-			'preference' => '_primary'
-		];
-		try {
-			$primary = $this->engine->get($primaryPayload);
-		} catch (\Elasticsearch\Common\Exceptions\Missing404Exception $e) {
-			$this->logger->error('Primary index does not exist.');
-			throw new Exception\MissingPrimaryIndex('Primary index not available.');
-		}
-		return $primary['_source']['name'];
+		return $this->primaryIndexStrategy->getPrimaryIndex();
+
 	}
 
 	/**
@@ -106,19 +110,7 @@ public function getPrimaryIndex()
 	 */
 	public function setPrimaryIndex($name)
 	{
-		if (!$this->engine->indices()->exists(['index' => $this->configurationIndexName])) {
-			$this->createCurrentIndexConfiguration();
-		}
-		$this->engine->index([
-			'index' => $this->configurationIndexName,
-			'type' => static::TYPE_CONFIGURATION,
-			'id' => static::PRIMARY_ID,
-			'body' => [
-				'name' => $name,
-				'timestamp' => time()
-			]
-		]);
-		$this->logger->debug('Primary index set.', compact('name'));
+		$this->primaryIndexStrategy->setPrimaryIndex($name);
 	}
 
 	/**
@@ -130,9 +122,7 @@ public function setPrimaryIndex($name)
 	 */
 	public function copyPrimaryIndexToSecondary($retryCount = 0)
 	{
-		if (!$this->engine->indices()->exists(['index' => $this->configurationIndexName])) {
-			$this->createCurrentIndexConfiguration();
-		}
+		$this->configurationIndex->createCurrentIndexConfiguration();
 		try {
 			$primaryName = $this->getPrimaryIndex();
 		} catch (\Elasticsearch\Common\Exceptions\ServerErrorResponseException $e) {
@@ -144,8 +134,8 @@ public function copyPrimaryIndexToSecondary($retryCount = 0)
 			return $this->copyPrimaryIndexToSecondary($retryCount++);
 		}
 		$id = $this->engine->index([
-			'index' => $this->configurationIndexName,
-			'type' => static::TYPE_CONFIGURATION,
+			'index' => (string)$this->configurationIndex,
+			'type' => ConfigurationIndex::TYPE_CONFIGURATION,
 			'body' => [
 				'name' => $primaryName,
 				'timestamp' => time()
@@ -170,14 +160,14 @@ public function getSecondaryIndices(\DateTime $olderThan = null, $disposition =
 			$olderThan = new \DateTime();
 		}
 		$params = [
-			'index' => $this->configurationIndexName,
-			'type' => static::TYPE_CONFIGURATION,
+			'index' => (string)$this->configurationIndex,
+			'type' => ConfigurationIndex::TYPE_CONFIGURATION,
 			'body' => [
 				'query' => [
 					'bool' => [
 						'must_not' => [
 							'term' => [
-								'_id' => static::PRIMARY_ID
+								'_id' => ConfigurationIndex::PRIMARY_ID
 							]
 						],
 						'filter' => [
@@ -231,51 +221,20 @@ public function deleteSecondaryIndices(\DateTime $olderThan = null)
 			if ($this->engine->indices()->exists(['index' => $indexToDelete['index']])) {
 				$results[$indexToDelete['index']] = [
 					'index' => $this->engine->indices()->delete(['index' => $indexToDelete['index']]),
-					'config' => $this->deleteConfigurationEntry($indexToDelete['configuration_id'])
+					'config' => $this->configurationIndex->deleteConfigurationEntry($indexToDelete['configuration_id'])
 				];
 				$this->logger->debug('Deleted secondary index.', compact('indexToDelete'));
 			} else {
 				$results[$indexToDelete] = [
 					'index' => null,
-					'config' => $this->deleteConfigurationEntry($indexToDelete['configuration_id'])
+					'config' => $this->configurationIndex->deleteConfigurationEntry($indexToDelete['configuration_id'])
 				];
 				$this->logger->debug('Index not found to delete.', compact('indexToDelete'));
 			}
 		}
 		return $results;
 	}
 
-	/**
-	 * Delete an entry from the configuration index.
-	 *
-	 * @param string $id
-	 * @return array
-	 */
-	private function deleteConfigurationEntry($id)
-	{
-		return $this->engine->delete([
-			'index' => $this->configurationIndexName,
-			'type' => static::TYPE_CONFIGURATION,
-			'id' => $id
-		]);
-	}
-
-	/**
-	 * Create the index needed to store the primary index name.
-	 *
-	 * @return void
-	 */
-	private function createCurrentIndexConfiguration()
-	{
-		$this->engine->indices()->create([
-			'index' => $this->configurationIndexName,
-			'body' => static::$elasticSearchConfigurationMapping
-		]);
-		$this->logger->debug('Configuration index created.', [
-			'index' => $this->configurationIndexName
-		]);
-	}
-
 	/**
 	 * Determines if the combined filter in query DSL is supported.
 	 *