extension-cirrussearch/f3aa628e7d75master
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README
MediaWiki extension: CirrusSearch
Installation
Get Elasticsearch up and running somewhere. 1.3.2 and above are all fine.
Optional: CirrusSearch makes use of sandboxed dynamic scripts in Elasticsearch. For most functions the sandbox is fine but some advanced features (source regular expression search) require relaxing the sandbox some. To do this add the contents of elasticsearch.yml located in this directory to the elasticsearch.yml that came with Elasticsearch and restart Elasticsearch.
Place the CirrusSearch extension in your extensions directory. Make sure you have the curl php library installed (sudo apt-get install php5-curl in Debian.) You also need to install the Elastica MediaWiki extension. Add this to LocalSettings.php: require_once( "$IP/extensions/Elastica/Elastica.php" ); require_once( "$IP/extensions/CirrusSearch/CirrusSearch.php" ); $wgDisableSearchUpdate = true;
Configure your search servers in LocalSettings.php if you aren't running Elasticsearch on localhost: $wgCirrusSearchServers = array( 'elasticsearch0', 'elasticsearch1', 'elasticsearch2', 'elasticsearch3' ); There are other $wgCirrusSearch variables that you might want to change from their defaults.
Now run this script to generate your elasticsearch index: php $MW_INSTALL_PATH/extensions/CirrusSearch/maintenance/updateSearchIndexConfig.php
Now remove $wgDisableSearchUpdate = true from LocalSettings.php. Updates should start heading to Elasticsearch.
Next bootstrap the search index by running: php $MW_INSTALL_PATH/extensions/CirrusSearch/maintenance/forceSearchIndex.php --skipLinks --indexOnSkip php $MW_INSTALL_PATH/extensions/CirrusSearch/maintenance/forceSearchIndex.php --skipParse Note that this can take some time. For large wikis read "Bootstrapping large wikis" below.
Once that is complete add this to LocalSettings.php to funnel queries to ElasticSearch: $wgSearchType = 'CirrusSearch';
Bootstrapping large wikis
Since most of the load involved in indexing is parsing the pages in php we provide a few options to split the process into multiple processes. Don't worry too much about the database during this process. It can generally handle more indexing processes then you are likely to be able to spawn.
General strategy: 0. Make sure you have a good job queue setup. It'll be doing most of the work. In fact, Cirrus won't work well on large wikis without it.
- Generate scripts to add all the pages without link counts to the index.
- Execute them any way you like.
- Generate scripts to count all the links.
- Execute them any way you like.
Step 1: In bash I do this: export PROCS=5 #or whatever number you want rm -rf cirrus_scripts mkdir cirrus_scripts mkdir cirrus_log pushd cirrus_scripts php extensions/CirrusSearch/maintenance/forceSearchIndex.php --queue --maxJobs 10000 --pauseForJobs 1000 \
--skipLinks --indexOnSkip --buildChunks 250000 | sed -e 's/$/ | tee -a cirrus_log\/'$wiki'.parse.log/' | split -n r/$PROCS
for script in x*; do sort -R $script > $script.sh && rm $script; done popd
Step 2: Just run all the scripts that step 1 made. Best to run them in screen or something and in the directory above cirrus_scripts. So like this: bash cirrus_scripts/xaa.sh
Step 3: In bash I do this: pushd cirrus_scripts rm *.sh php extensions/CirrusSearch/maintenance/forceSearchIndex.php --queue --maxJobs 10000 --pauseForJobs 1000 \
--skipParse --buildChunks 250000 | sed -e 's/$/ | tee -a cirrus_log\/'$wiki'.parse.log/' | split -n r/$PROCS
for script in x*; do sort -R $script > $script.sh && rm $script; done popd
Step 4: Same as step 2 but for the new scripts. These scripts put more load on Elasticsearch so you might want to run them just one at a time if you don't have a huge Elasticsearch cluster or you want to make sure not to cause load spikes.
If you don't have a good job queue you can try the above but lower the buildChunks parameter significantly and remove the --queue parameter.
Handling elasticsearch outages
If for some reason in process updates to elasticsearch begin failing you can immediately set "$wgDisableSearchUpdate = true;" in your LocalSettings.php file to stop trying to update elasticsearch. Once you figure out what is wrong with elasticsearch you should turn those updates back on and then run the following: php ./maintenance/forceSearchIndex.php --from <whenever the outage started in ISO 8601 format> --deletes php ./maintenance/forceSearchIndex.php --from <whenever the outage started in ISO 8601 format>
The first command picks up all the deletes that occurred during the outage and should complete quite quickly. The second command picks up all the updates that occurred during the outage and might take significantly longer.
PoolCounter
CirrusSearch can leverage the PoolCounter extension to limit the number of concurrent searches to elasticsearch. You can do this by installing the PoolCounter extension and then configuring it in LocalSettings.php like so: require_once( "$IP/extensions/PoolCounter/PoolCounterClient.php"); $wgPoolCounterConf = array( 'CirrusSearch-Search' => array( // Configuration for all searches
'class' => 'PoolCounter_Client', 'timeout' => 30, 'workers' => 50, 'maxqueue' => 10,
) );
Upgrading
When you upgrade there four possible cases for maintaining the index:
- You must update the index configuration and reindex from source documents.
- You must update the index configuration and reindex from already indexed documents.
- You must update the index configuration but no reindex is required.
- No changes are required.
If you must do (1) you have two options: A. Blow away the search index and rebuild it from scratch. Marginally faster and uses less disk space on in elasticsearch but empties the index entirely and rebuilds it so search will be down for a while: php updateSearchIndexConfig.php --startOver php forceSearchIndex.php
B. Build a copy of the index, reindex to it, and then force a full reindex from source documents. Uses more disk space but search should be up the entire time: php updateSearchIndexConfig.php --reindexAndRemoveOk --indexIdentifier now php forceSearchIndex.php
If you must do (2) really have only one option: A. Build of a copy of the index and reindex to it: php updateSearchIndexConfig.php --reindexAndRemoveOk --indexIdentifier now php forceSearchIndex.php --from <time when you started updateSearchIndexConfig.php in YYYY-mm-ddTHH:mm:ssZ> --deletes php forceSearchIndex.php --from <time when you started updateSearchIndexConfig.php in YYYY-mm-ddTHH:mm:ssZ> or for the Bash inclined: TZ=UTC export REINDEX_START=$(date +%Y-%m-%dT%H:%m:%SZ) php updateSearchIndexConfig.php --reindexAndRemoveOk --indexIdentifier now php forceSearchIndex.php --from $REINDEX_START --deletes php forceSearchIndex.php --from $REINDEX_START
If you must do (3) you again only have one option: A. Same as (2.A)
4 is easy!
The safest thing if you don't know what is required for your update is to execute (1.B).
Production suggestions
Elasticsearch
All the general rules for making Elasticsearch production ready apply here. So you don't have to go round them up below is a list. Some of these steps are obvious, others will take some research.
- NOTE: this list was written for 0.90 so it may not work well for 1.0. It'll be revised when I have
more experience with 1.0. --Nik
- Have >= 3 nodes.
- Configure Elasticsearch for memlock.
- Change each node's elasticsearch.yml file in a few ways.
3a. Change node name to the real host name. 3b. Turn off autocreation and some other scary stuff by adding this (tested with 0.90.4):
- Actions #########
- Modulo some small changes to comments this section comes directly from the
- wonderful Elasticsearch mailing list, specifically Dan Everton. ##
- Require explicit index creation. ES never autocreates the indexes the way we
- like them. ## action.auto_create_index: false
## - Protect against accidental close/delete operations on all indices. You can
- still close/delete individual indices. ## action.disable_close_all_indices: true action.disable_delete_all_indices: true
## - Disable ability to shutdown nodes via REST API. ## action.disable_shutdown: true
Testing
See tests/browser/README
Job Queue
Cirrus makes heavy use of the job queue. You can run it without any job queue customization but if you switch the job queue to Redis with checkDelay enabled then Cirrus's results will be more correct. The reason for this is that this configuration allows Cirrus to delay link counts until Elasticsearch has appropriately refreshed. This is an example of configuring it: $redisPassword = '<password goes here>'; $wgJobTypeConf['default'] = array( 'class' => 'JobQueueRedis', 'order' => 'fifo', 'redisServer' => 'localhost', 'checkDelay' => true, 'redisConfig' => array(
'password' => $redisPassword,
), ); $wgJobQueueAggregator = array( 'class' => 'JobQueueAggregatorRedis', 'redisServer' => 'localhost', 'redisConfig' => array(
'password' => $redisPassword,
), );
Note: some MediaWiki setups have trouble running the job queue. It can be finicky. The most sure fire way to get it to work is also the slowest. Add this to your LocalSettings.php: $wgRunJobsAsync = false;
Development
The fastest way to get started with CirrusSearch development is to use MediaWiki-Vagrant.
- Follow steps here: https://www.mediawiki.org/wiki/MediaWiki-Vagrant#Quick_start
- Now execute the following:
vagrant enable-role cirrussearch vagrant provision
This can take some time but it produces a clean development environment in a virtual machine that has everything required to run Cirrus.
Hooks
CirrusSearch provides hooks that other extensions can make use of to extend the core schema and modify documents.
There are currently two phases to building cirrus documents: the parse phase and the links phase. The parse phase then the links phase is run when the article's rendered text would change (actual article change and template change). Only the links phase is run when an article is newly links or unlinked.
Note that this whole thing is a somewhat experimental feature at this point and the API hasn't really been settled.
'CirrusSearchAnalysisConfig': Allows to hook into the configuration for analysis &config - multi-dimensional configuration array for analysis of various languages and fields $builder - instance of MappingConfigBuilder, for easier use of utility methods to build fields
'CirrusSearchMappingConfig': Allows configuration of the mapping of fields &config - multi-dimensional configuration array that contains Elasticsearch document configuration.
The 'page' index contains configuration for Elasticsearch documents representing pages. The 'namespace' index contains namespace configuration for Elasticsearch documents representing namespaces.
Licensing information
CirrusSearch makes use of the Elastica library to connect to elasticsearch http://elastica.io/. It is Apache licensed and you can read the license Elastica/LICENSE.txt.