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https://issues.apache.org/jira/browse/SOLR-14371?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jan Høydahl updated SOLR-14371:
-------------------------------
Description:
With v3.5, Zookeeper supports [dynamic
reconfig|https://zookeeper.apache.org/doc/r3.6.0/zookeeperReconfig.html]. Solr
will happily connect to an ensemble with dynamic reconfiguration enabled, but
it is not "aware of it". The ZK Status screen does not display whether the
ensemble is in reconfig mode and is not able to load the dynamic set of hosts
from zk.
This JIRA aims to make the ZookeeperStatusHandler able to display zk status as
well as show status for all zk hosts in the ensemble, even ones that are not
part of the static connection string that Solr is aware of. It will also show
warnings if Solr's static zk connection string is out of sync with the truth.
Currently Solr has a static ZK connection string and is not able to
re-configure itself when zk cluster is reconfigured. Fixing this is not part of
this issue but is deferred to SOLR-14389.
I discovered this while experimenting with the [solr-operator for
Kubernetes|https://github.com/bloomberg/solr-operator]. It configures a
reconfigurable ZK ensemble and configures a single LB host:port as its zk
connection string. This issue will flag a warning in this case since the
connection string is different from the set of zk hosts in zk node
{{/zookeeper/config}}. This warning can be removed once Solr fully supports
dynamic reconfiguration.
was:
With zk 3.5 it supports dynamic reconfig, which is used by the solr-operator
for Kubernetes. Then Solr is given a zkHost of one url pointing to a LB
(Service) in front of all zookeepers, and the zkclient will then fetch list of
all zookeepers from special zknode /zookeeper/config and reconfigure itself
with connection to all zk nodes listed. So you can then scale up/down number of
zk nodes dynamically without restarting solr.
However, the Admin UI displays errors since it believes it is connected to only
one zk, which is contradictory to what zk itself reports. We need to make
ZookeeperStatusHandler aware of dynamic reconfig so it asks zkclient what
current zkHost is instead of relying on Zk_HOST static setting.
> Zk StatusHandler should know about dynamic zk config
> ----------------------------------------------------
>
> Key: SOLR-14371
> URL: https://issues.apache.org/jira/browse/SOLR-14371
> Project: Solr
> Issue Type: Bug
> Security Level: Public(Default Security Level. Issues are Public)
> Reporter: Jan Høydahl
> Assignee: Jan Høydahl
> Priority: Major
> Attachments: dynamic-reconfig-warning.png, dynamic-reconfig.png
>
> Time Spent: 50m
> Remaining Estimate: 0h
>
> With v3.5, Zookeeper supports [dynamic
> reconfig|https://zookeeper.apache.org/doc/r3.6.0/zookeeperReconfig.html].
> Solr will happily connect to an ensemble with dynamic reconfiguration
> enabled, but it is not "aware of it". The ZK Status screen does not display
> whether the ensemble is in reconfig mode and is not able to load the dynamic
> set of hosts from zk.
> This JIRA aims to make the ZookeeperStatusHandler able to display zk status
> as well as show status for all zk hosts in the ensemble, even ones that are
> not part of the static connection string that Solr is aware of. It will also
> show warnings if Solr's static zk connection string is out of sync with the
> truth.
> Currently Solr has a static ZK connection string and is not able to
> re-configure itself when zk cluster is reconfigured. Fixing this is not part
> of this issue but is deferred to SOLR-14389.
> I discovered this while experimenting with the [solr-operator for
> Kubernetes|https://github.com/bloomberg/solr-operator]. It configures a
> reconfigurable ZK ensemble and configures a single LB host:port as its zk
> connection string. This issue will flag a warning in this case since the
> connection string is different from the set of zk hosts in zk node
> {{/zookeeper/config}}. This warning can be removed once Solr fully supports
> dynamic reconfiguration.
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