t3g/elasticorn

elastic manager based on elastica

5.0.0 2017-08-23 09:09 UTC

README

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Elasticorn is an elasticsearch manager based on elastica. It's main feature is zero-down-time remapping of data. Find the project homepage at http://elasticorn.net/.

Compatibility

  • Releases 1.x are compatible with elasticsearch 2.x.
  • Releases 5.x are compatible with elasticsearch 5.x.

Features

  • Zero-down time remapping of an index (including data-transfer)
  • Initialize indices based on config files
  • Show and compare mapping configurations

Zero downtime remapping - How it works:

Elasticorn uses aliases to allow zero downtime remapping of an index. For each configured index elasticorn creates an index_a and index_b and uses an alias to point to the current active index. When applying a new mapping the currently inactive index is deleted and recreated with the new mapping. The data is then copied from the old to the new index. After the data transfer successfully completes the alias is pointed to the new index.

Step by Step

  • Your applications index is not called like in your config.
  • Your applications index is indeed two separate indices and your configured index name is only an alias to the current live-index. We refer to the other index as the "standby-index".
  • When changing the mapping of an index, all data of that index has to be deleted because your mapping might influence the way how your data had been analyzed before.
  • Elasticorn will determine if your mapping has changed in between runs
  • Elasticorn will determine which index is your current live-index and switch to your standby index
  • Elasticorn will then apply your new mappings onto the standby index
  • Elasticorn will copy all data from your live-index to the (freshly mapped) standby-index. This will analyze your data again as you would expect.
  • Once finished, Elasticorn will change the alias from the "old" live-index to the "old" standby-index. This way the standby-index becomes the new live-index
  • Elasticorn will delete all data from your "old" live-index to free up resources.
  • Since switching the alias is an atomic action, your users will not experience any downtime whatsoever.
  • Enjoy providing an awesome service to your users.

Installation

Composer based:

composer require T3G/elasticorn

Download as .phar:

Download the phar and the phar.pubkey file to a folder of your choice. If you want to be able to run elasticorn from anywhere make sure your folder is in your PATH. As the phar is signed the pubkey file should simply be in the same folder as the phar.

Elasticsearch Client Configuration

Elasticorn assumes default connection parameters for establishing a connection to elasticsearch. If you are using a non-default setup you can configure those connection settings in a .env file. For details see below.

Index and Mapping Configuration

For elasticorn to work, your configuration needs to be structured in the following way and be defined as yaml.

- MAIN configuration directory
  - Elasticorn.yaml*
  - IndexName directory
    - IndexConfiguration.yaml
    - DocumentTypes directory
      - documenttype.yaml (for example: tweets.yaml)

* optional

Example

project
│   README.md    
└───Elasticorn
	└── t3_forger
    		├── DocumentTypes
    		│   ├── issue.yaml
    		│   ├── review.yaml
    		│   └── user.yaml
    		└── IndexConfiguration.yaml

In our case the Elasticorn holds all information about our indices. Multiple indices can be managed by creating new folders.

The IndexConfiguration.yaml file specifies configuration parameters for the index (for example shards or replicas.)

The folder called DocumentTypes holds our type mapping with a file per document type.

The syntax is pretty straightforward yaml syntax which will then be parsed as an array.

The filename will determine the name of your document type in Elasticsearch.

We'll take a look at user.yaml here:

id:
  type: integer
username:
  type: string
  index: not_analyzed
  store: true
fullname:
  type: string
  index: not_analyzed
  store: true
email:
  type: integer
  index: not_analyzed
  store: true
avatar:
  type: string

For an example on how the configuration should look like, see the Tests/Fixtures/Configuration folder in this project. For a list of available configuration options see the elastica documentation.

You can use a .env file, a command line parameter or the interactive console to specify your configuration directory.

.env configuration

You can specify your configuration directory as well as specific connection params in a .env file which should be placed in the folder where elasticorn gets executed. The following variables may be configured:

configurationPath=
elastica.host=
elastica.port=
elastica.path=
elastica.url=
elastica.transport=
elastica.persistent=
elastica.timeout=
elastica.username=
elastica.password=

Configuring Languages

Elasticorn is able to automatically generate indices per language if your setup matches the following basic conditions:

  • one index per language
  • default language analyzers are configured per field in your configuration
  • documents only have one language each

If those conditions match add a config file called "Elasticorn.yaml" in your index directory, for example with this configuration:

languages:
  - english
  - german
  - french

The language name has to be the name of an analyzer available in elasticsearch. On index initialization the following indices and aliases will be created:

Indices:
  - indexname_english_a
  - indexname_english_b
  - indexname_german_a
  - indexname_german_b
  - indexname_french_a
  - indexname_french_b

Aliases:
  - indexname_english
  - indexname_german
  - indexname_french
  - indexname (pointing to first configured language)

You can add additional languages after initialization by calling index:remap.

Usage

composer based usage command:

./elasticorn.php -h

phar usage command:

./elasticorn.phar -h

Commands

  • index:init - Initializes all configured indices
  • index:remap - applies a new mapping configuration to an existing index
  • index:cornify - Converts a conventional index to an elasticorn index
  • mapping:compare - allows comparison of currently applied and configured mapping
  • mapping:show - shows currently applied mapping

Contributions and issues

All contributions are welcome. If you find any bugs, have problems or simply want to request a new feature feel free to add it to the issue tracker.

If you want to contribute code-wise, fork the repository and create a pull request.

Running the tests

Elasticorn comes with unit and acceptance tests.

Unit tests

You can run the unit test suite with bin/phpunit -c Build phpunit.xml.

Acceptance tests

Note: The acceptance tests need a clean elasticsearch instance on localhost:9200 - do not execute these tests if you have other indices configured that you still need. The tests delete all indices at various points.

You can run the acceptance test suite with bin/behat -c Tests/Acceptance/behat.yml.