SMU Classification: Restricted Yes zookeeper supports dynamic change from 3.5.x. I am referring to Solr here.
You would need to specify the list of zookeeper servers in solr.in.sh or solr.in.cmd or as -z param. https://lucene.apache.org/solr/guide/8_1/setting-up-an-external-zookeeper-ensemble.html But scaling zookeeper after helm deployment does not change this list of ZK_HOST automatically, this is intended as helm/k8s does not do this for you and you should not change this manually. K8s has DNS that allow you to resolve a single domain name to multiple IP. Let say this domain is zk-headless. Then ZK_HOST="zk-headless:2181". Solr should resolve all instance of zookeeper from a single domain name. nslookup zk-headless Server: xxx Address: xxx Non-authoritative answer: Name: zk-headless Addresses: 10.0.0.11 10.0.0.12 10.0.0.13 This three addresses will be the zookeeper servers. -----Original Message----- From: Jörn Franke <jornfra...@gmail.com> Sent: Thursday, September 26, 2019 6:41 PM To: solr-user@lucene.apache.org Subject: Re: How to resolve a single domain name to multiple zookeeper IP in Solr The newest zk version supports dynamic change of the zk instances: https://zookeeper.apache.org/doc/r3.5.3-beta/zookeeperReconfig.html However, for that to work properly in case of a Solr restart you always need a minimal set of servers that do not change and just increase/decrease additional ones. > Am 26.09.2019 um 12:22 schrieb LEE Ween Jiann <wjlee.2...@phdcs.smu.edu.sg>: > > I'm trying to modify the helm chart for solr such that it works for > kubernetes (k8s) deployment correctly. There needs to be a particular change > in the way solr resolves zookeepers hostname in order for this to happen. > > Let me explain... > The standard way to configure solr is by listing all the zookeeper > hostname/IP in either: > > * solr.in.sh or solr.in.cmd > * zoo.cfg > * -z param > For example: ZK_HOST="zk1:2181,zk2:2181,zk3:2181". > > However, when it comes to cloud deployment, in particular on k8s using helm > chart, this is not an ideal situation as the user is required to modify > zk_host each time they scale the number of zookeeper up/down. > > * For example (scale down): ZK_HOST="zk1:2181,zk2:2181". > * For example (scale up): ZK_HOST="zk1:2181,zk2:2181,zk3:2181,zk4:2181". > > This cannot be done automatically using in helm/k8s. In k8s, this parameter > should remain static, meaning that it should not be changed after deployment > of the chart. > > * For example (k8s): ZK_HOST="zk-headless:2181". > > What a chart can do is to create a service with a DNS name such as > zk-headless that contains all the IP of the zookeepers, and as zookeeper > scales, the number of IP resolved from zk-headless changes. Could solr to > resolve multiple zookeeper IPs from a single name? > > Cheers, > Ween Jiann
