56 lines
2.9 KiB
Plaintext
56 lines
2.9 KiB
Plaintext
---
|
|
layout: docs
|
|
page_title: Consul vs. Serf
|
|
sidebar_title: Serf
|
|
description: >-
|
|
Serf is a node discovery and orchestration tool and is the only tool discussed
|
|
so far that is built on an eventually-consistent gossip model with no
|
|
centralized servers. It provides a number of features, including group
|
|
membership, failure detection, event broadcasts, and a query mechanism.
|
|
However, Serf does not provide any high-level features such as service
|
|
discovery, health checking or key/value storage. Consul is a complete system
|
|
providing all of those features.
|
|
---
|
|
|
|
# Consul vs. Serf
|
|
|
|
[Serf](https://www.serf.io) is a node discovery and orchestration tool and is the only
|
|
tool discussed so far that is built on an eventually-consistent gossip model
|
|
with no centralized servers. It provides a number of features, including group
|
|
membership, failure detection, event broadcasts, and a query mechanism. However,
|
|
Serf does not provide any high-level features such as service discovery, health
|
|
checking or key/value storage. Consul is a complete system providing all of those
|
|
features.
|
|
|
|
The internal [gossip protocol](/docs/internals/gossip) used within Consul is in
|
|
fact powered by the Serf library: Consul leverages the membership and failure detection
|
|
features and builds upon them to add service discovery. By contrast, the discovery
|
|
feature of Serf is at a node level, while Consul provides a service and node level
|
|
abstraction.
|
|
|
|
The health checking provided by Serf is very low level and only indicates if the
|
|
agent is alive. Consul extends this to provide a rich health checking system
|
|
that handles liveness in addition to arbitrary host and service-level checks.
|
|
Health checks are integrated with a central catalog that operators can easily
|
|
query to gain insight into the cluster.
|
|
|
|
The membership provided by Serf is at a node level, while Consul focuses
|
|
on the service level abstraction, mapping single nodes to multiple services.
|
|
This can be simulated in Serf using tags, but it is much more limited and does
|
|
not provide useful query interfaces. Consul also makes use of a strongly-consistent
|
|
catalog while Serf is only eventually-consistent.
|
|
|
|
In addition to the service level abstraction and improved health checking,
|
|
Consul provides a key/value store and support for multiple datacenters.
|
|
Serf can run across the WAN but with degraded performance. Consul makes use
|
|
of [multiple gossip pools](/docs/internals/architecture) so that
|
|
the performance of Serf over a LAN can be retained while still using it over
|
|
a WAN for linking together multiple datacenters.
|
|
|
|
Consul is opinionated in its usage while Serf is a more flexible and
|
|
general purpose tool. In [CAP](https://en.wikipedia.org/wiki/CAP_theorem) terms,
|
|
Consul uses a CP architecture, favoring consistency over availability. Serf is an
|
|
AP system and sacrifices consistency for availability. This means Consul cannot
|
|
operate if the central servers cannot form a quorum while Serf will continue to
|
|
function under almost all circumstances.
|