+ * @see LBFactory::__construct()
+ *
+ * Template override precedence (highest => lowest):
+ * - templateOverridesByServer
+ * - masterTemplateOverrides
+ * - templateOverridesBySection/templateOverridesByCluster
+ * - externalTemplateOverrides
+ * - serverTemplate
+ * Overrides only work on top level keys (so nested values will not be merged).
+ *
+ * Server configuration maps should be of the format Database::factory() requires.
+ * Additionally, a 'max lag' key should also be set on server maps, indicating how stale the
+ * data can be before the load balancer tries to avoid using it. The map can have 'is static'
+ * set to disable blocking replication sync checks (intended for archive servers with
+ * unchanging data).
+ *
+ * @param array $conf Parameters of LBFactory::__construct() as well as:
+ * - sectionsByDB Map of database names to section names.
+ * - sectionLoads 2-d map. For each section, gives a map of server names to
+ * load ratios. For example:
+ * [
+ * 'section1' => [
+ * 'db1' => 100,
+ * 'db2' => 100
+ * ]
+ * ]
+ * - serverTemplate Server configuration map intended for Database::factory().
+ * Note that "host", "hostName" and "load" entries will be
+ * overridden by "sectionLoads" and "hostsByName".
+ * - groupLoadsBySection 3-d map giving server load ratios for each section/group.
+ * For example:
+ * [
+ * 'section1' => [
+ * 'group1' => [
+ * 'db1' => 100,
+ * 'db2' => 100
+ * ]
+ * ]
+ * ]
+ * - groupLoadsByDB 3-d map giving server load ratios by DB name.
+ * - hostsByName Map of hostname to IP address.
+ * - externalLoads Map of external storage cluster name to server load map.
+ * - externalTemplateOverrides Set of server configuration maps overriding
+ * "serverTemplate" for external storage.
+ * - templateOverridesByServer 2-d map overriding "serverTemplate" and
+ * "externalTemplateOverrides" on a server-by-server basis.
+ * Applies to both core and external storage.
+ * - templateOverridesBySection 2-d map overriding the server configuration maps by section.
+ * - templateOverridesByCluster 2-d map overriding the server configuration maps by external
+ * storage cluster.
+ * - masterTemplateOverrides Server configuration map overrides for all master servers.
+ * - loadMonitorClass Name of the LoadMonitor class to always use.
+ * - readOnlyBySection A map of section name to read-only message.
+ * Missing or false for read/write.