If you specify the node parameter for ADDREPLICA I don't think so, but as you know you have to understand the topology via CLUSTERSTATUS or some such.
If you don't specify the "node" parameter, I think if you take a look at the "Rule-based Replica Placement" here: https://lucene.apache.org/solr/guide/6_6/rule-based-replica-placement.html. I have to say you'll have to experiment here, I haven't verified that ADDREPLICA does the right thing here. Do note that this functionality will be superseded by the "Policy" framework but the transition is pretty straightforward. Best, Erick On Wed, Dec 20, 2017 at 3:45 PM, Greg Roodt <gro...@gmail.com> wrote: > Thanks again Erick. It looks like I've got this working. > > One final question I think: > Is there a way to prevent ADDREPLICA from adding another core if a core for > the collection already exists on the node? > > I've noticed that if I call ADDREPLICA twice for the same IP:PORT_solr, I > get multiple cores. I can probably check `clusterstatus`, but I was > wondering if there is another way to make the ADDREPLICA call idempotent. > > > > On 21 December 2017 at 03:27, Erick Erickson <erickerick...@gmail.com> > wrote: > >> The internal method is ZkController.generateNodeName(), although it's >> fairly simple, there are bunches of samples in ZkControllerTest.... >> >> But yeah, it requires that you know your hostname and port, and the >> context is "solr"..... >> >> On Tue, Dec 19, 2017 at 8:04 PM, Greg Roodt <gro...@gmail.com> wrote: >> > Ok, thanks. I'll take a look into using the ADDREPLICA API. >> > >> > I've found a few examples of the znode format. It seems to be >> IP:PORT_solr >> > (where I presume _solr is the name of the context or something?). >> > >> > Is there a way to discover what a znode is? i.e. Can my new node >> determine >> > what it's znode is? Or is my only option to use the IP:PORT_solr >> convention? >> > >> > >> > >> > >> > On 20 December 2017 at 11:33, Erick Erickson <erickerick...@gmail.com> >> > wrote: >> > >> >> Yes, ADDREPLICA is mostly equivalent, it's also supported going >> forward.... >> >> >> >> LegacyCloud should work temporarily, I'd change it going forward though. >> >> >> >> Finally, you'll want to add a "node" parameter to insure your replica is >> >> placed on the exact node you want, see the livenodes znode for the >> >> format... >> >> >> >> On Dec 19, 2017 16:06, "Greg Roodt" <gro...@gmail.com> wrote: >> >> >> >> > Thanks for the reply. So it sounds like the method that I'm using to >> >> > automatically add replicas on Solr 6.2 is not recommended and not >> going >> >> to >> >> > be supported in future versions. >> >> > >> >> > A couple of follow up questions then: >> >> > * Do you know if running with legacyCloud=true will make this >> behaviour >> >> > work "for now" until I can find a better way of doing this? >> >> > * Will it be enough for my newly added nodes to then startup solr >> (with >> >> > correct ZK_HOST) and call the ADDREPLICA API as follows? >> >> > ``` >> >> > curl http://localhost:port >> >> > /solr/admin/collections?action=ADDREPLICA&collection= >> blah&shard=*shard1* >> >> > ``` >> >> > That seems mostly equivalent to writing that core.properties file >> that I >> >> am >> >> > using in 6.2 >> >> > >> >> > >> >> > >> >> > >> >> > >> >> > On 20 December 2017 at 09:34, Shawn Heisey <apa...@elyograg.org> >> wrote: >> >> > >> >> > > On 12/19/2017 3:06 PM, Greg Roodt wrote: >> >> > > > Thanks for your reply Erick. >> >> > > > >> >> > > > This is what I'm doing at the moment with Solr 6.2 (I was >> mistaken, >> >> > > before >> >> > > > I said 6.1). >> >> > > > >> >> > > > 1. A new instance comes online >> >> > > > 2. Systemd starts solr with a custom start.sh script >> >> > > > 3. This script creates a core.properties file that looks like >> this: >> >> > > > ``` >> >> > > > name=blah >> >> > > > shard=shard1 >> >> > > > ``` >> >> > > > 4. Script starts solr via the jar. >> >> > > > ``` >> >> > > > java -DzkHost=....... -jar start.jar >> >> > > > ``` >> >> > > >> >> > > The way that we would expect this to be normally done is a little >> >> > > different. Adding a node to the cloud normally will NOT copy any >> >> > > indexes. You have basically tricked SolrCloud into adding the >> replica >> >> > > automatically by creating a core before Solr starts. SolrCloud >> >> > > incorporates the new core into the cluster according to the info >> that >> >> > > you have put in core.properties, notices that it has no index, and >> >> > > replicates it from the existing leader. >> >> > > >> >> > > Normally, what we would expect for adding a new node is this: >> >> > > >> >> > > * Run the service installer script on the new machine >> >> > > * Add a ZK_HOST variable to /etc/default/solr.in.sh >> >> > > * Use "service solr restart"to get Solr to join the cloud >> >> > > * Call the ADDREPLICA action on the Collections API >> >> > > >> >> > > The reason that your method works is that currently, the "truth" >> about >> >> > > the cluster is a mixture of what's in ZooKeeper and what's actually >> >> > > present on each Solr instance. >> >> > > >> >> > > There is an effort to change this so that ZooKeeper is the sole >> source >> >> > > of truth, and if a core is found that the ZK database doesn't know >> >> > > about, it won't be started, because it's not a known part of the >> >> > > cluster. If this goal is realized in a future version of Solr, then >> >> the >> >> > > method you're currently using is not going to work like it does at >> the >> >> > > moment. I do not know how much of this has been done, but I know >> that >> >> > > there have been people working on it. >> >> > > >> >> > > Thanks, >> >> > > Shawn >> >> > > >> >> > > >> >> > >> >> >>
