Solr with Apache Tomcat (http://wiki.apache.org/solr/SolrTomcat)

March 14, 2012 § 1 Comment

Simple Example Install

Installing Tomcat 6

Apache Tomcat is a web application server for Java servlets. These are instructions for manually installing Tomcat 6 on Linux, recommended because distribution Tomcats are either old or quirky.

Create the solr user. As solr, extract the Tomcat 6.0 download into /opt/tomcat6, hereafter referred to as the $CATALINA_HOME directory.

Edit $CATALINA_HOME/conf/tomcat-users.xml to enable the manager login as user “tomcat” with password “tomcat” (insecure):

 

<role rolename="manager"/>
<role rolename="admin"/>
<user username="tomcat" password="tomcat" roles="manager,admin"/>

Start Tomcat with $CATALINA_HOME/bin/catalina.sh run. Tomcat runs on the port defined $CATALINA_HOME/conf/server.xml, configured by default to port 8080.

The startup script tomcat6 can be placed in /etc/init.d/tomcat6 on CentOS/RedHat/Fedora so that you can start Tomcat using service tomcat6 start. Use chkconfig to enable the tomcat6 service to start on boot.

Building Solr

Skip this section if you have a binary distribution of Solr. These instructions are for building Solr from source, if you have a nightly tarball or have checked out the trunk from subversion athttp://svn.apache.org/repos/asf/lucene/dev/trunk. Assumes that you have JDK 1.6 already installed.

In the source directory, run ant dist to build the .war file under dist. Build the example for the Solr tutorial by running ant example. Change to the ‘example’ directory, run java -jar start.jarand visit localhost:8983/solr/admin to test that the example works with the Jetty container.

Installing Solr instances under Tomcat

Assuming that Solr and its example are built, this is how to install the Solr example as an instance under Tomcat.

Copy the example/solr directory from the source to the installation directory like /opt/solr/example/solr, herafter $SOLR_HOME. Copy the .war file dist/apache-solr-*.war into $SOLR_HOMEas solr.war.

The configuration file $SOLR_HOME/conf/solrconfig.xml in the example sets dataDir for the index to be ./solr/data relative to the current directory – which is true for running the Jetty server provided with the example, but incorrect for Tomcat running as a service. Modify the dataDir to specify the full path to $SOLR_HOME/data:

  •   <dataDir>${solr.data.dir:/opt/solr/example/solr/data}</dataDir>

The dataDir can also be temporarily overridden with the JAVA_OPTS environment variable prior to starting Tomcat:

  •   export JAVA_OPTS="$JAVA_OPTS -Dsolr.data.dir=/opt/solr/example/solr/data"

Create a Tomcat Context fragment to point docBase to the $SOLR_HOME/solr.war file and solr/home to $SOLR_HOME:

 

<?xml version="1.0" encoding="utf-8"?>
<Context docBase="/opt/solr/example/solr/solr.war" debug="0" crossContext="true">
  <Environment name="solr/home" type="java.lang.String" value="/opt/solr/example/solr" override="true"/>
</Context>

Symlink or place the file in $CATALINA_HOME/conf/Catalina/localhost/solr-example.xml, where Tomcat will automatically pick it up. Tomcat deletes the file on undeploy (which happens automatically if the configuration is invalid).

Repeat the above steps with different installation directories to run multiple instances of Solr side-by-side.

If Tomcat is not already running, start it with service tomcat6 start or $CATALINA_HOME/bin/startup.sh run. The Solr admin should be available at http://<host&gt;:8080/solr-example/admin.

Single Solr Instance

If you are sure that you will only ever run one instance of Solr, you can do away with the Context fragment by placing the .war in $CATALINA_HOME/webapps/solr-example.war and setting the Solr home through a global environment variable prior to starting Tomcat:

 

export JAVA_OPTS="$JAVA_OPTS -Dsolr.solr.home=/opt/solr/example"

Troubleshooting

Login to Tomcat Management page does not work

$CATALINA_HOME/conf/tomcat-users.xml may be missing the correct user line.

Tomcat Manager does not list Solr

The Context fragment may be invalid. Examine $CATALINA_HOME/tomcat6/logs/catalina.out.

Exceptions when visiting Solr admin

View $CATALINA_HOME/logs/catalina.out for a better view of the exceptions. Probably caused by an incorrect path in solrconfig.xml or the Context fragment, or by an unclean build (run ant clean and rebuild the source).

HTTP 500 error

If, when installing Solr 3.5, you get an HTTP 500 error and the exception message begins with

org.apache.solr.common.SolrException: Error loading class 'solr.VelocityResponseWriter' at org.apache.solr.core.SolrResourceLoader.findClass(SolrResourceLoader.java:389)...

the problem is caused by incorrect <lib> locations in $SOLR_HOME/conf/solrconfig.xml and can be fixed by reading through this note in the mailing list archive: http://mail-archives.apache.org/mod_mbox/lucene-solr-user/201112.mbox/%3C7FA7F0B0-935A-4D01-A389-DB3B7EDA0464@gmail.com%3E

关于这个问题的补充说明

中告诉我们,要在使用tomcat6.0时避免这个错误,要么注释 <queryResponseWriter name=”velocity”http://wiki.apache.org/solr/VelocityResponseWriter&#8221; style=”color: rgb(0, 68, 170); border-top-width: 0px; border-right-width: 0px; border-bottom-width: 0px; border-left-width: 0px; border-style: initial; border-color: initial; border-image: initial; text-decoration: none; “>VelocityResponseWriter” enable=”${solr.velocity.enabled:true}”/>,要么将${solr.velocity.enabled:true}”/修改为${solr.velocity.enabled:false}”/,要么就得将solrconfig.xml中的<lib dir=”../../contrib/extraction/lib” /><lib dir=”../../contrib/clustering/lib” />这些相对目录的地址调整为正确的(因为大多数情况下我们都是从example\solr下copy的solrconfig.xml,因此里面的目录位置肯定与实际位置不相符合),修改的时候一定要注意dir=”../../contrib/extraction/lib”这个地址的相对位置是对于$SOLR_HOME/conf/来说的,而不是$SOLR_HOME/conf/solrconfig.xml

Optional Configuration

Logging

For information about controlling JDK Logging (aka: java.util logging) in Tomcat, please consult the Tomcat docs… http://tomcat.apache.org/tomcat-6.0-doc/logging.html

URI Charset Config

If you are going to query Solr using international characters (>127) using HTTP-GET, you must configure Tomcat to conform to the URI standard by accepting percent-encoded UTF-8.

Edit Tomcat’s conf/server.xml and add the following attribute to the correct Connector element: URIEncoding=”UTF-8″.

 

<Server ...>
 <Service ...>
   <Connector ... URIEncoding="UTF-8"/>
     ...
   </Connector>
 </Service>
</Server>

This is only an issue when sending non-ascii characters in a query request… no configuration is needed for Solr/Tomcat to return non-ascii chars in a response, or accept non-ascii chars in an HTTP-POST body.

Configuring Solr Home with JNDI

A Tomcat context fragments can be used to configure the JNDI property needed to specify your Solr Home directory.

Just put a context fragment file under $CATALINA_HOME/conf/Catalina/localhost that looks something like this…

$ cat /tomcat55/conf/Catalina/localhost/solr.xml

 

<Context docBase="/some/path/solr.war" debug="0" crossContext="true" >
   <Environment name="solr/home" type="java.lang.String" value="/my/solr/home" override="true" />
</Context>

A few things to keep in mind:

  • The “conf/Catalina/localhost” directory may not exist by default in your installation. You may have to create it.
  • “/some/path/solr.war” is the absolute path to where ever you want to keep the Solr war using the appropriate syntax for your Operating System. In Tomcat 5.5 and later, the war file must be stored outside of the webapps directory for this to work. Otherwise, this entire Context element is ignored.
  • “/my/solr/home” should be to where you have created your Solr Home directory, using the appropriate syntax for your Operating System.
  • Prior to Tomcat 5.5, a “path” attribute was required for Context elements (starting with 5.5, the path attribute must not be used except when statically defining a Context in server.xml, as it will be inferred from the Context fragment filename.

Enabling Longer Query Requests

If you try to submit too long a GET query to Solr, then Tomcat will reject your HTTP request on the grounds that the HTTP header is too large; symptoms may include an HTTP 400 Bad Request error or (if you execute the query in a web browser) a blank browser window.

If you need to enable longer queries, you can set the maxHttpHeaderSize attribute on the HTTP Connector element in your server.xml file. The default value is 4K. (See http://tomcat.apache.org/tomcat-5.5-doc/config/http.html)

 

Multiple Solr Webapps

Tomcat context fragments make configuring multiple Solr webapps (with JNDI) in a single Tomcat server easy.

Just follow the previous instructions for “Configuring Solr Home with JNDI” to create a seperate context fragment file under $CATALINA_HOME/conf/Catalina/localhost for each solr webapp you want to run:

$ cat /tomcat55/conf/Catalina/localhost/solr1.xml

 

<Context docBase="/some/path/solr.war" debug="0" crossContext="true" >
   <Environment name="solr/home" type="java.lang.String" value="/some/path/solr1home" override="true" />
</Context>

$ cat /tomcat55/conf/Catalina/localhost/solr2.xml

 

<Context docBase="f:/solr.war" debug="0" crossContext="true" >
   <Environment name="solr/home" type="java.lang.String" value="/some/path/solr2home" override="true" />
</Context>

Don’t put anything related to Solr under the webapps directory.

The solr home directories are configured via JNDI in the context fragment, and in the examples above will be /some/path/solr1home and /some/path/solr2home The URLs to the two webapps will be http://host:port/solr1 and http://host:port/solr2

Tomcat on Windows

Single Solr app

  • Download and install Tomcat for Windows using the MSI installer. Install it with the tcnative.dll file. Say you installed it in c:\tomcat\

  • Check if Tomcat is installed correctly by going to http://localhost:8080/

  • Change the c:\tomcat\conf\server.xml file to add the URIEncoding Connector element as shown above.
  • Download and unzip the Solr distribution zip file into (say) c:\temp\solrZip\
  • Make the “solr home” directory called, where you intend the application server to function, say c:\web\solr\
  • Copy the contents of the example\solr directory c:\temp\solrZip\example\solr\ to c:\web\solr\
  • Stop the Tomcat service
  • Copy the *solr*.war file from c:\temp\solrZip\dist\ to the Tomcat webapps directory c:\tomcat\webapps\
  • Rename the *solr*.war file solr.war
  • Configure Tomcat to recognize the solr home directory you created, by adding the Java Options -Dsolr.solr.home=c:\web\solr and -Dsolr.velocity.enabled=false
    • either use the system tray icon to add the java option
    • or manually edit the environment script c:\tomcat\bin\setenv.bat and add it to JAVA_OPTS
  • * Note: For Tomcat 7 and Solr3.4(last version on 2011-09-23), the above option on setenv.bat may not work, so you could not use it and put this code fragment
    on $CATALINA_HOME/conf/Catalina/localhost/solr.xml

    <?xml version="1.0" encoding="UTF-8"?>
    <Context docBase="C:\apache-tomcat-7.0.21\webapps\solr.war" debug="0" crossContext="true" >
        <Environment name="solr/home" type="java.lang.String" value="C:\solr" override="true" />
    </Context>
  • Start the Tomcat service
  • Go to the solr admin page to verify that the installation is working. It will be at http://localhost:8080/solr/admin

Multiple Solr apps

  • Download and install Tomcat for Windows using the MSI installer. Install it with the tcnative.dll file. Say you installed it in c:\tomcat\

  • Check if Tomcat is installed correctly by going to http://localhost:8080/

  • Change the c:\tomcat\conf\server.xml file to add the URIEncoding Connector element as shown above.
  • Download and unzip the Solr distribution zip file into (say) c:\temp\solrZip\
  • Say you need two apps in c:\web\solr1 and c:\web\solr2; create these two directories
  • Copy the contents of the example\solr directory c:\temp\solrZip\example\solr\ to c:\web\solr1\ and to c:\web\solr2\
  • Stop the Tomcat service
  • Copy the *solr*.war file from c:\temp\solrZip\dist\ to the Tomcat lib directory c:\tomcat\lib\
  • Rename the *solr*.war file solr.war
  • Make a new text file in c:\tomcat\conf\Catalina\localhost called solr1.xml with the following code fragment
    <Context docBase="c:\tomcat\lib\solr.war" debug="0" crossContext="true" >
       <Environment name="solr/home" type="java.lang.String" value="c:\web\solr1" override="true" />
    </Context>
  • Make a new text file in c:\tomcat\conf\Catalina\localhost called solr2.xml with the following code fragment
    <Context docBase="c:\tomcat\lib\solr.war" debug="0" crossContext="true" >
       <Environment name="solr/home" type="java.lang.String" value="c:\web\solr2" override="true" />
    </Context>
  • Start the Tomcat service
  • Go to the solr admin pages for the 2 webapps to verify that the installation is working. It will be at http://localhost:8080/solr1/admin and http://localhost:8080/solr2/admin

64-bit Note

The MSI installer that installs Tomcat as a Windows service isn’t prepared to support 64-bit Windows out of the box. There are some straightforward workarounds, though. See http://stackoverflow.com/questions/211446/how-to-run-tomcat-6-on-winxp-64-bit

//!\\ TODO //!\\

Indicate how to index in tomcat (rather than built-in jetty support via start.jar).

External Resources

http://www.ibm.com/developerworks/java/library/j-solr1/

Troubleshooting Errors

It’s possible that you get an error related to the following:

 

SEVERE: Exception starting filter SolrRequestFilter
java.lang.NoClassDefFoundError: Could not initialize class org.apache.solr.core.SolrConfig
        at org.apache.solr.servlet.SolrDispatchFilter.init(SolrDispatchFilter.java:76)
.........
Caused by: java.lang.RuntimeException: XPathFactory#newInstance() failed to create an XPathFactory for the default object model: http://java.sun.com/jaxp/xpath/dom with the XPathFactoryConfigurationException: javax.xml.x
path.XPathFactoryConfigurationException: No XPathFctory implementation found for the object model: http://java.sun.com/jaxp/xpath/dom
        at javax.xml.xpath.XPathFactory.newInstance(Unknown Source)

This is due to your tomcat instance not having the xalan jar file in the classpath. It took me some digging to find this, and thought it might be useful for others. The location varies from distribution to distribution, but I essentially just added (via a symlink) the jar file to the shared/lib directory under the tomcat directory.

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