CODEWITHSUNDEEP
apache-zookeeperconsul
Santosh Bhosle
Santosh Bhosle

Reputation: 153

Leader Election : Consul vs ZooKeeper

We are choosing the best option for implementing a leader election to achieve high availability. Our goal is to have only a single instance active at any given time. We are using Spring Boot to develop application which is getting deployed by default on Tomcat. Would be great to hear your opinion about the following options:

Does Zookeeper provide better CP than Consul ?

View on maintenance/complexity ?

Upvotes: 5

Views: 2711

Answers (1)

Saptarshi Basu
Saptarshi Basu

Reputation: 9283

ZooKeeper is based on ZAB & Consul is based on Raft. Both are very similar atomic broadcast algorithms at a high level. So, as far as "Consistancy" of CAP (which is actually linearizability, a very strong form of consistancy) is concerned, both will provides similar guarantees. Both of them have linearizable writes to quorum (majority). The other nodes (not in quorum) may lag in updates by default resulting in stale reads. This is done this way because complete linearizability makes things slow and many applications are good with a little stale reads. However, if that is not acceptable in a particular usecase, it is always possible to use sync call before read in ZooKeeper and Consistent mode in Consul to acheive complete linearizability.

For service discovery, however, Consul seems to provide higher level constructs that are not out-of-the-box in ZooKeeper.

In terms of leader election use case, both can be used.

But given that ZooKeeper is used by many top level apache projects and it is also older than the Raft and therefore Consul, I hope it will have better community support and documentation. Also the Apache documentation providing various recepes is great.

Finally, if you go with ZooKeeper, you may also want to use Apache Curator which provides higher level APIs on top of ZooKeeper.

Upvotes: 6

Related Questions