I am setting up Solr Cloud (3 Solr node ) with external Zookeeper and I need to expose zookeeper URL to end user , so that zookeeper can automatically determine available sole node and return it to end user.
Does anyone know if this is feasible in Solr ? This is required for High Availability support as if one of Solr node goes down then end user should be automatically redirected to another instance of Solr.
Thanks
Shashi
Related
I have a Node.js app and I used to have a standalone Solr but then our company decided to use SolrCloud to provide failover.
In the standalone Solr I had only the one server with it and I had all my requests like: http://solr_server:8983/solr/mycore/select?indent=on&q=*:*&wt=json so all requests led to the same server all the time.
But now I have 3 different instances with 1 ZooKeeper and 1 Solr node on each of them and my requests look like this: http://solr_server_1:8983/solr/mycollection/select?q=*:*
And now the question: what if the solr_server_1 will go down? How can I still get my results? How can I handle requests in this case?
If you're doing this manually: You'll have to catch the exception when the connection fails, and then retry the next server in your list.
let servers = ['ip1:8983', 'ip2:8983', 'ip3:8983']
If you're using a library that supports Zookeeper (i.e. it connects to zookeeper to find out what the live nodes are), you give the client a list of zookeeper nodes and lets it figure out the rest. node-solr-smart-client is a client that supports Zookeeper as well.
options = {
zkConnectionString: 'ip1:2181,ip2:2181,ip3:2181',
// etc.
}
solrSmartClient.createClient('my_solr_collection', options, function (err, solrClient) {
I followed the instructions listed in Getting started with the Retrieve and Rank service to create solr cluster, however I received the following message : WRRCSR42:The requesting service instance may not create any more free solar clusters(current limit:1)
My Questions: what this message mean? and what should I do to get the cluster id?
Thank you,
The error tells you that you've already created a Solr Cluster. IBM Watson R&R only provides one free cluster.
To retrieve the list of existing clusters, you can use the same endpoint as when you attempt to create the cluster, but issue a regular GET request instead of a POST request.
https://gateway.watsonplatform.net/retrieve-and-rank/api/v1/solr_clusters
The response lists your existing Solr clusters, and includes your solr_cluster_id
Or will I need to implement another solutions like say RabbitMQ for message queuing and some other service for load balancing along with it? Please point me into the right direction.
You are setting up solr in CloudSolr mode. You can use the solrj java client implementation for load balancing the indexes and search queries to solr. CloudSolrServer is a class in the Solrj client for connecting to the Solr cloud.
It connects to Zookeeper and keeps track of the state of each node in the cluster. With this knowledge, CloudSolrServer client knows which nodes are the leaders and sends requests to leaders only to save time. Without CloudSolrServer, requests are sent in a round-robin fashion to all the Solr nodes (Leaders and Replicas). So there is S/N chance of getting the current Shard leader where N is the total number of nodes in the cloud (i.e. sum of leaders and replicas = N) and S is the number of Shard-Leaders. There are (1-S/N) chances of hitting the non-leader node which is wasteful as the non-leader node would then have to pass the request to its leader. With CloudSolrServer, requests are sent only to Shard-Leaders which performs much better.
If a node crashes, ZooKeeper notifies CloudSolrServer about the same so that CloudSolrServer removes it from the eligible solr instances' list. If a new leader is elected, then also CloudSolrServer clients are notified.
In fact, Solr actually uses the CloudSolrServer internally to communicate with other nodes in the cluster.
You don't need any type of queuing mechanism while working with Solr.
We have a cluster of standalone Solr cores (Solr 4.3) for which we had built some custom plugins. I'm now trying to prototype converting the cluster to a Solr Cloud cluster. This is how I am trying to deploy the cores (in 4.7.2).
Start solr with zookeeper embedded.
java -DzkRun -Djetty.port=8985 -jar start.jar
upload a config into Zookeeper (same config as the standalone cores)
zkcli.bat -zkhost localhost:9985 -cmd upconfig -confdir myconfig -confname myconfig
Create a new collection (mycollection) of 2 shards using the Collections API
http://localhost:8985/solr/admin/collections?action=CREATE&name=mycollection&numShards=2&replicationFactor=1&maxShardsPerNode=2&collection.configName=myconfig
So at this point I have two shards under my solr directory with the appropriate core.properties
But when I go to http://localhost:8985/solr/#/~cloud, I see that the two shards' status is "Down" when they are supposed to be active by default.
And when I try to index documents in them using SolrJ (via CloudSolrServer API) , I get the error "No live SolrServers available to handle this request". I restarted Solr but same issue.
private CloudSolrServer cloudSolr;
cloudSolr = new CloudSolrServer(zkHOST);
cloudSolr.setZkClientTimeout(zkClientTimeout);
cloudSolr.setDefaultCollection(collectionName);
cloudSolr.connect();
cloudSolr.add(doc)
What am I doing wrong? I did a lot of digging around and saw an old Jira bug saying that Solr Cloud shards won't be active until there are some documents in the index. If that is the reason, that's kind of like a catch-22 isn't it?
So anyways, I also tried adding some test documents manually and committed to see if things improved. Now on the shard statistics page, it correctly gives me the Numdocs count but when I try to query it says "no servers hosting shard". I next tried passing in shards.tolerant=true as a query parameter and search, but no cigar. It says 0 documents found.
Any help would be appreciated. My main objective is to rebuilt the old standalone cores using SolrCloud and test to see if our custom requesthandlers still work as expected. And at this point, I can't index documents inside of the 4.7 Solr Cloud collection I have created.
Thanks and Regards
I'm trying to tweak our system status check to see the state of the Solr nodes in our SolrCloud. I'm facing the following problems:
We send a query to each of the Solr nodes separately. If we get a response and the status of the response is 0, we assume the node is running. Unfortunately, we've seen cases in which the node is recovering or even down and select queries are still handled.
In hope to prevent this, we've added a check which sends a ping request to solr. If the status returned by this is request reads 'OK' we assume the node is up. Unfortunately even with this request, if the node is recovering or down, this check won't fail.
My question is: What is the correct way to check the status of a node in SolrCloud?
If you are using a SolrCloud, it's recommended to maintain an explicit zookeeper ensemble as well. Because zookeeper ensemble maintains the SolrCloud's current status of each node and each shard wise. This status is actually get reflected from the SolrCloud admin window.
Go to the Admin window. Click on "Cloud".
Then click on "Tree" to get a tree view of your SolrCloud architecture.
Click /clusterstate.json to view the SolrCloud status.
This (clusterstate.json) json file holds the SolrCloud status information. Now if you are running an explicit zookeeper ensemble, following are the steps to get SolrCloud status.
Go to the path "zookeeper/installation/directory/bin"
Execute ./zkCli.sh -server ZK_IP:ZK_PORT (E.g ./zkCli.sh -server localhost:2181)
Execute get /clusterstate.json
You'll find the SolrCloud status.
Note : ZK_IP - The HOST IP where zoopeeper is running.
ZK_PORT - Zookeeper's client port.
You actually don't want /clusterstate.json - as this only covers the case where collections are already present. From ZooKeeper you need /live_nodes
Because Zookeeper is the authority for what Solr Nodes are members of the Solr cloud cluster, it follows that you should go to it first, to discover what members are accessible. This is how all Solr cloud clients work, and probably is the best way to approach the problem.
/live_nodes contains a file for each live Solr node, regardless of what collections exist or where the replicas are located.
Once you have resolved /live_nodes... you can call clusterstatus on any Solr instance with the address and port from one of the live-nodes.
http://localhost:8983/solr/admin/collections?action=clusterstatus&wt=json
clusterstatus provides a detailed overview of Solr nodes, collections, replicas, etc. Everything you would want to know.
As a final note, it's very wise to set SOLR_HOST inside of solr.in.sh configuration (/etc/default/solr.in.sh) - by default 'localhost' is used to reference the solr node. Setting this value to the public address you want the Solr node identified by will prevent ZooKeeper from returning the address "localhost" to clients when attempting to reach a Solr Node.