Apache Solr Reference Guide Covering Apache Solr 6.0

Substituting Properties in Solr Config Files
Solr supports variable substitution of property values in config files, which allows runtime specification of various
configuration options in solrconfig.xml . The syntax is ${propertyname[:option default value] }.
This allows defining a default that can be overridden when Solr is launched. If a default value is not specified,
then the property must be specified at runtime or the configuration file will generate an error when parsed.
There are multiple methods for specifying properties that can be used in configuration files.
JVM System Properties
Any JVM System properties, usually specified using the -D flag when starting the JVM, can be used as variables
in any XML configuration file in Solr.
For example, in the sample solrconfig.xml files, you will see this value which defines the locking type to use:
${solr.lock.type:native}
Which means the lock type defaults to "native" but when starting Solr, you could override this using a JVM
system property by launching the Solr it with:
bin/solr start -Dsolr.lock.type=none
In general, any Java system property that you want to set can be passed through the bin/solr script using the
standard -Dproperty=value syntax. Alternatively, you can add common system properties to the SOLR_OPTS
environment variable defined in the Solr include file ( bin/solr.in.sh). For more information about how the
Solr include file works, refer to: Taking Solr to Production.
solrcore.properties
If the configuration directory for a Solr core contains a file named solrcore.properties that file can contain
any arbitrary user defined property names and values using the Java standard properties file format, and those
properties can be used as variables in the XML configuration files for that Solr core.
For example, the following solrcore.properties file could be created in the conf/ directory of a collection
using one of the example configurations, to override the lockType used.
#conf/solrcore.properties
solr.lock.type=none
The path and name of the solrcore.properties file can be overridden using the properties prop
erty in core.properties.
User defined properties from core.properties
If you are using a core.properties file with solr.xml, then any user defined properties in that file may be
specified there and those properties will be available for substitution when parsing XML configuration files for that
Solr core.
For example, consider the following core.properties file:
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