Apache Curator: Invalid config event received

The exception looks like this: We know, that in zookeeper.properties (or zoo.cfg) there is a cluster configuration of the following type: From a certain version of ZooKeeper, it became like this https://zookeeper.apache.org/doc/r3.5.3-beta/zookeeperReconfig.html#ch_reconfig_format: Apache Curator switched to a new format, discontinuing support for the old one. However, ZooKeeper kept it: on the same page in the […]

READ MORE

ZooKeeper recursive watcher

If you need to set up a recursive watchers (watch on all nodes), the standard ZooKeeper’s Watcher class will not help much – it is installed on only 1 node (or one-level-forward when you calling getChildren()), and is also a one-time event. This means that after each watch trigger, you need to install a new […]

READ MORE

How ZooKeeper ACL works

In this post I will describe the basic principles of how ACL works in ZooKeeper. ACL is not set recursively and is not inherited by the child nodes. If we have a read-only ACL for /path1/path2 or /path1/path2/path3, then deleting /path1 will fail, regardless of AСL of /path1. Several ACL records can be set on […]

READ MORE

Apache Atlas – Building & Installing

Let’s say we want to got working Apache Atlas instance with embedded Hbase & Solr on our machine. Notice, that you need to install JDK 8 before start. Go to the Apache Atlas GitHub page, and download the zip file with the source code of the latest stable release from here: https://github.com/apache/atlas/releases Important notice: DO […]

READ MORE

ZooKeeper x509 certificates ACL

The documentation states that setting an ACL via the ZooKeeper CLI usually works like this: In the case of the x509 scheme, the Authenticated ID for the user is the DN string of their certificate. In confirmation of this, when a user connects via a certificate, there is a line in the server log: Now, […]

READ MORE

SSL / TLS setup for ZooKeeper

We have a ZooKeeper server and a java client application that connects to it. SSL has appeared in ZooKeeper since version 3.5.: https://issues.apache.org/jira/browse/ZOOKEEPER-2125 Server Tuning There are several types of ZooKeeper server distribution. We’ll cover the standalone version as well as the Apache Kafka version. We need a configured server for start. The setup process […]

READ MORE