Solr Cloud Support

Solr Cloud is supported by io.ino.solrs.CloudSolrServers, which is a SolrServers implementation (can be passed to RoundRobinLB/FastestServerLB).

Solr Cloud is supported with the following properties / restrictions:

• Standard collection aliases are supported, no support for (time) routed aliases (see also Collections API / CreateAlias docs)
• Can use a default collection, if this is not provided, per request the SolrQuery must specify the collection via the “collection” parameter.
• New solr servers or solr servers that changed their state from inactive (e.g. down) to active can be tested with warmup queries before they’re used for load balancing queries, for this a WarmupQueries instance can be set.
• Querying solr is possible when ZooKeeper is temporarily not available
• Construction of CloudSolrServers is possible while ZooKeeper is not available. When ZK becomes available CloudSolrServers will be connected to ZK. As interval for trying to connect the CloudSolrServers.zkConnectTimeout property is (re)used (10 seconds by default). Connection is tried “forever”, but of course this does not prevent CloudSolrServers or AsyncSolrClient to be shutdown.
• Construction of CloudSolrServers is possible when no solr instances are known by ZK. When solr servers have registered at ZK, CloudSolrServers will notice this. As retry interval the CloudSolrServers.clusterStateUpdateInterval property is (re)used (1 second by default).
• ZK cluster state updates are read using the CloudSolrServers.clusterStateUpdateInterval.

To run solrs connected to SolrCloud / ZooKeeper, you pass an instance of CloudSolrServers to RoundRobinLB/FastestServerLB. The simplest case looks like this:

Java

copysourceCloudSolrServers<?> servers = CloudSolrServers.builder("localhost:2181").build();
JavaAsyncSolrClient solr = JavaAsyncSolrClient.builder(new RoundRobinLB(servers)).build();

Scala

copysourceval servers = new CloudSolrServers("localhost:2181")
val solr = AsyncSolrClient.Builder(RoundRobinLB(servers)).build

Here’s an example that shows all configuration properties in use:

Java

copysourceCloudSolrServers<?> servers = CloudSolrServers.builder("host1:2181,host2:2181")
  .withZkClientTimeout(15, SECONDS)
  .withZkConnectTimeout(10, SECONDS)
  .withClusterStateUpdateInterval(1, SECONDS)
  .withDefaultCollection("collection1")
  .withWarmupQueries((collection) -> Collections.singletonList(new SolrQuery("*:*")), 10)
  .build();
JavaAsyncSolrClient solr = JavaAsyncSolrClient.builder(new RoundRobinLB(servers)).build();

Scala

copysourceval servers = new CloudSolrServers(
  zkHost = "host1:2181,host2:2181",
  zkClientTimeout = 15 seconds,
  zkConnectTimeout = 10 seconds,
  clusterStateUpdateInterval = 1 second,
  defaultCollection = Some("collection1"),
  warmupQueries = WarmupQueries("collection1" => Seq(new SolrQuery("*:*")), count = 10))
val solr = AsyncSolrClient.Builder(RoundRobinLB(servers)).build

When running SolrCloud you should also configure a retry policy (RetryPolicy.TryAvailableServers to be concrete), because restarts of solr nodes are not that fast registered by ZooKeeper (and therefore also not by our CloudSolrServers), so that for a short period of time queries might be failing because a solr node just became not available.