Indexing and crawling a website with Solr

This page describes how to configure the Content Indexer submodule of the Magnolia Solr module to index Magnolia workspaces and crawl a website. Solr module allows you to use Apache Solr, a standalone enterprise-grade search server with a REST-like API, for indexing and crawling Magnolia content, especially if you need to manage assets in high volumes (100,000+ DAM assets).

Configuring Solr clients

From version 5.2 the Solr module supports multiple Solr servers/cores. You can configure a client for every server/core under Configuration > /modules/solr-search-provider/config/solrClientConfigs. It's recommended to have one client named default. This default client is used when no specific client is defined for the indexer, crawler, or search result page template.

If you need to have more servers/cores, duplicate the default client and change the baseURL property to point to another server/core.

Node name	Value
solr-search-provider
config
solrClientConfigs
default
allowCompression	false
baseURL	http://localhost:8983/solr/magnolia
connectionTimeout	100
soTimeout	1,000

The value entered for the baseURL property should conform with the following syntax:

<protocol>://<domain_name>:<port>/solr/<solr_core_name>

If the Solr server is installed as described in Installing Apache Solr, then the value is http://localhost:8983/solr/magnolia. For a description of the other properties see the HttpSolrClient.Builder Javadoc and Using SolrJ - Common Configuration Options.

Indexing Magnolia workspaces

The Content Indexer module is a recursive repository indexer and an event based indexer. You can configure multiple indexers for different sites and document types. The content indexer also allows you to crawl external websites using JSoup and CSS selectors. You then define different field mappings that will be obtained for each node and indexed in the Solr index.

IndexService

Both the indexer and the crawler use the IndexService to handle the indexing of a content. A basic implementation is configured by default: info.magnolia.search.solrsearchprovider.logic.indexer.BasicSolrIndexService. You can define and configure your own IndexService for specific needs.

Implement the IndexService interface:

IndexService

public class I18nIndexerService implements info.magnolia.module.indexer.indexservices.IndexService {

   private static final Logger log = LoggerFactory.getLogger(I18nIndexerService.class);

   @Override
   public boolean index(Node node, IndexerConfig config) {
      ...

For a globally configured indexing service, register the IndexService in the configuration of the Content Indexer module. For your custom indexing service, use the indexServiceClass (see above in the properties table):

Node name	Value
modules
content-indexer
config
indexServiceClass	info.magnolia.search.solrsearchprovider.logic.indexer.BasicSolrIndexService

Indexer configuration

You can configure an indexer in Configuration > /modules/content-indexer/config/indexers. See an example configuration for indexing assets and folders in the DAM workspace or the below example configuration for indexing of content in the website workspace:

Node name	Value
modules
content-indexer
config
indexers
websiteIndexer
clients
default	default
fieldMappings
abstract	abstract
author	author
date	date
teaserAbstract	mgnlmeta_teaserAbstract
text	content
title	title
enabled	true
indexed	false
pull	false
rootNode	/
type	website
workspace	website

Properties

`enabled`	required `true` enables the indexer configuration. `false` disables the indexer configuration.
`indexed`	required Indicates whether indexing was done. When Solr finishes indexing content-indexer will set this property to `true`. You can set it to `false` to trigger re-indexing.
`nodeType`	optional, default is `mgnl:page` JCR node type to index. For example, if you were indexing assets in the Magnolia DAM you would set this to `mgnl:asset`.
`pull`	optional, default is `false` (push) Pull URLs instead of pushing. When `true` Solr will use Tika to extract information from a document, for instance a PDF. When `false` it will push the collected information using a Solr document.
`assetProviderId`	optional , default is `jcr` If `pull` is set to true, specify an assetProviderId to obtain an asset correctly.
`rootNode`	required Node in the workspace where indexing starts. Use this property to limit indexing to a particular site branch.
`type`	required Sets the type of the indexed content such as `website` or `documents`. When you search the index you can filter results by type.
`workspace`	required Workspace to index.
`indexServiceClass`	optional (Solr module version 5.2+) Custom IndexService used by this indexer. If not defined, the global one is used.
`fieldMappings`	required Field mappings defines how fields in Magnolia content are mapped to Solr fields. Left side is Magnolia, right side is Solr.
`<Magnolia_field>`	`<Solr_field>` You can use the fields available in the schema. If a field does not exist in Solr's schema you can use a dynamic field `mgnlmeta_*` . For instance if you have information nested in a deep leaf of your page stored with property `specComponentAbstract` , you can map this field with `mgnlmeta_specComponentAbstract` . The indexer contains a recursive call which will explore the node's child leaves until it finds the property.
`clients`	optional, default is `default` (Solr module version 5.2+) Solr clients which will be used by this indexer. Allows to index content for multiple instances of Solr.
`<client-name>`

Crawler configuration

The crawler mechanism uses the Scheduler to crawl a site periodically.

You can configure crawlers in Configuration > /modules/content-indexer/config/crawlers/.

Crawler properties

`enabled`	required `true` enables the crawler. `false` disables the crawler. When a crawler is enabled `info.magnolia.module.indexer.CrawlerIndexerFactory` registers a new scheduler job for the crawler automatically.
`depth`	required The max depth of a page in terms of distance in clicks from the root page. This should not be too high, ideally 2 or 3 max.
`nbrCrawlers`	required The max number of simultaneous crawler threads that crawl a site. 2 or 3 is enough.
`crawlerClass`	optional, since version 3.0, default value is `info.magnolia.module.indexer.crawler.MgnlCrawler` Implementation of `edu.uci.ics.crawler4j.crawler.WebCrawler` which is used by the Crawler to crawl sites.
`catalog`	optional, since version 3.0, default value is `content-indexer` Name of the catalog where the command resides.
`command`	optional, since version 3.0, default value is `crawlerIndexer` Command which is used to instantiate and trigger the crawler.
`activationOnly`	optional, since version 3.0 If it's set to true then crawler should be triggered only during activation. No scheduler job will be registered for this crawler. The `jcrItems` property (see below) has to be configured too for this feaure to work.
`delayAfterActivation`	optional, since version 3.0, default value is `5s` Defines the delay (in seconds) after which crawler should start when activation is done. Default value is 5s.
`cron`	optional, default is every hour `0 0 0/1 1/1 ? ` A CRON expression that specifies how often the site will be crawled. CronMaker is a useful tool for building expressions.
`type`	optional Sets the type of the crawled content such as `news`. When you search the index you can filter results by type.
`indexServiceClass`	optional, since version 5.2 Custom IndexService used by this crawler. If not defined, the global one is used.
`clients`	optional, since version 5.2 , default is `default` client Solr clients which will be used by this indexer. Allows index content into multiple Solr instances.
`<client-name>`	required Name of the client.
`fieldMappings`	required Field mappings defines how fields parsed from the site pages are mapped to Solr fields. Left side is Solr field, right side is the crawled site.
`<site_field>`	required You can use any CSS selector to target an element on the page. For example, `#story_continues_1` targets an element by ID. You can also use custom syntax to get content inside attributes. For example, meta keywords are extracted using `meta[name=keywords] attr(0,content)`. This will extract first value of keywords meta element. If you don't specify anything after the CSS selector then the text contained in the element is indexed. `meta[name=keywords]` would return an empty string because a meta element does contain any text, keywords are in the attributes. To get the value of a specific attribute specify `attr(<index>,<Solr_field_name>)`. If you set `index=-1` then all attributes are extracted and separated by a semicolon `;`.
`jcrItems`	optional , since version 3.0 List of JCR items. If any of this items is activated crawler will be triggered.
`<item_name>`	optional, since version 3.0 Name of the JCR item.
`workspace`	required, since version 3.0 Workspace where JCR item is stored.
`path`	required, since version 3.0 Path of the JCR item.
`siteAuthenticationConfig`	optional , since version 5.0.2 Authentication information to allow crawling password restricted area.
`username`	required, since version 5.0.2 Username which is used for login into restricted area.
`password`	required, since version 5.0.2 User's password used for login into restricted area.
`loginUrl`	required, since version 5.0.2 Url to page with login form.
`usernameField`	required, since version 5.0.2, default value is `mgnlUserID` Name of input field for entering the username in login form.
`passwordField`	required, since version 5.0.2, default value is `mgnlUserPSWD` Name of input field for entering the password in login form.
`logoutUrlIdentifier`	required, since version 5.0.2, default value is `mgnlLogout` String which identifies the logout Url. Crawler doesn't crawl over the urls which contains `logoutUrlIdentifier` to avoid logout.

Example: Configuration to crawl www.bbc.co.uk (Click to expand.)

Node name	Value
bbc_co_uk
clients
default	default
sites
bbc
url	http://www.bbc.co.uk/
fieldMappings
abstract	#story_continues_1
keywords	meta[name=keywords] attr(0,content)
depth	2
enabled	false
nbrCrawlers	2
type	news

Configuration of crawler commands

You can configure crawler commands in Configuration > /modules/content-indexer/commands/.

By default, the crawler mechanism is connected with the CleanSolrIndexCommand to clean the index from outdated indexes (pages). The CleanSolrIndexCommand is chained before the CrawlerIndexerCommand.

Node name	Value
modules
content-indexer
config
indexers
crawlers
commands
content-indexer	Note: Name of the folder is referenced by the crawler `catalog` property.
<crawler-name>	Note: Name of the node is referenced by the crawler `command` property.
cleanSolr
class	`info.magnolia.search.solrsearchprovider.logic.commands.CleanSolrIndexCommand`
<crawler-name>	Note: Name of the node is arbitrary.
class	`info.magnolia.module.indexer.crawler.commands.CrawlerIndexerCommand`

Properties for the cleanSolr command

`max`	optional, since version 5.0.1, default value is `500` Maximum number of documents to be checked.
`onlyHead`	optional, since version 5.5.1, default value is `false` If set to `true`, only the `head` of the page is requested instead of fetching the whole page. If the `deleteNoIndex` property is set to `true`, then this configuration is ignored, because the `robots` meta tag cannot be resolved from the `head` request.
`followRedirects`	optional, since version 5.5.2, default value is `false` If set to `true`, redirects are followed and the status code of the last page is evaluated.
`statusCodes`	optional, since version 5.0.1 List of status codes. If a page returns any of the status codes listed, then the page will be removed from the index. By default, there is no list but if a page returns 404 at any time, the page is removed from the index.
`deleteNoIndex`	optional, since version 5.5.4, default value is `false` If set to `true`, then also pages with the `robots` meta tag set to `noindex` will be removed from the index.
`skipIfAlreadyRunning`	optional, since version 5.5.1, default value is `false` If set to `true`, any previously running `CleanSolrIndexCommand` is finished and the new one is skipped. Normally, if the `CleanSolrIndexCommand` is already running for the crawler, it is stopped and a new one is started.

Crawling triggered by publishing (activation)

From version 3.0, crawlers can also be connected with the publishing (activation) process by adding info.magnolia.module.indexer.crawler.commands.CrawlerIndexerActivationCommand into command chain with activation command. By default, this is done for these commands:

If you are using the Publishing module:
- catalog: default, command: publish - configured under /modules/publishing-core/commands/default/publish
- catalog: default, command: unpublish - configured under /modules/publishing-core/commands/default/unpublish

If you are using the Activation module:
- catalog: default, command: activation - configured under /modules/activation/commands/default/activate/activate
- catalog: default, command: deactivate - configured under /modules/activation/commands/default/deactivate

catalog: default, command: personalizationActivation - configured under /modules/personalization-integration/commands/default/personalizationActivation

If you are using custom activation command and you wish to connect it with crawler mechanism, you can use info.magnolia.module.indexer.setup.AddCrawlerIntoCommandChainTask install/update task for it.

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