Enable support for configsets in Solr Docker image.

[kaladay]

Description

The core.properties is the default main one. A legacy.properties is provided as an example and as a convenience for using the older schema. All additional cores will use the default unless a properties file is named after it.

This also adds the ability to customize the solr configuration, such as changing port and access control. This is done by copying the default solr.xml. Make any modifications to this file for those changes to be copied over.

This also fixes a security concern where the core directories and files are given world/global read and write access. See the chmod commands near the bottom of the Dockerfile.

Example:

docker build --build-arg=MAIN_CORE="sage-discovery-1" --build-arg=EXTRA_CORES="sage-discovery-2 sage-discovery-3 sage-discovery-4 legacy" -t local_solr .

That example will build 5 cores, the first 4 will use the default core.properties. The last core, named legacy, will use the legacy.core.

[coveralls]

Coverage: 45.803% (-0.02%) from 45.825% when pulling 666d56e01ea9633fd314065aecde90caa503253c on solr-configsets into 60ffade591593f6c1828c585104d0b9451de4742 on staging.