2014-02-08 00:41:03 +00:00
|
|
|
---
|
|
|
|
|
layout: "intro"
|
2014-04-10 20:51:08 +00:00
|
|
|
page_title: "Consul vs. Chef, Puppet, etc."
|
2014-02-08 00:41:03 +00:00
|
|
|
sidebar_current: "vs-other-chef"
|
|
|
|
|
---
|
|
|
|
|
|
2014-04-10 20:51:08 +00:00
|
|
|
# Consul vs. Chef, Puppet, etc.
|
2014-02-08 00:41:03 +00:00
|
|
|
|
2014-04-10 20:51:08 +00:00
|
|
|
It is not uncommon to find people using Chef, Puppet, and other configuration
|
|
|
|
|
management tools to build service discovery mechanisms. This is usually
|
|
|
|
|
done by querying global state to construct configuration files on each
|
2014-04-14 18:53:29 +00:00
|
|
|
node during a periodic convergence run.
|
|
|
|
|
|
|
|
|
|
Unfortunately, this approach has
|
2014-04-10 20:51:08 +00:00
|
|
|
a number of pitfalls. The configuration information is static,
|
|
|
|
|
and cannot update any more frequently than convergence runs. Generally this
|
|
|
|
|
is on the interval of many minutes or hours. Additionally, there is no
|
|
|
|
|
mechanism to incorporate the system state in the configuration. Nodes which
|
|
|
|
|
are unhealthy may receive traffic exacerbating issues further. Using this
|
|
|
|
|
approach also makes supporting multiple datacenters challenging as a central
|
|
|
|
|
group of servers must manage all datacenters.
|
2014-02-08 00:41:03 +00:00
|
|
|
|
2014-04-10 20:51:08 +00:00
|
|
|
Consul is designed specifically as a service discovery tool. As such,
|
|
|
|
|
it is much more dynamic and responsive to the state of the cluster. Nodes
|
|
|
|
|
can register and deregister the services they provide, enabling dependent
|
|
|
|
|
applications and services to rapidly discover all providers. By using the
|
2014-04-16 03:17:00 +00:00
|
|
|
integrated health checking, Consul can route traffic away from unhealthy
|
|
|
|
|
nodes, allowing systems and services to gracefully recover. Static configuration
|
2014-04-10 20:51:08 +00:00
|
|
|
that may be provided by configuraiton management tools can be moved into the
|
|
|
|
|
dynamic key/value store. This allows application configuration to be updated
|
|
|
|
|
without a slow convergence run. Lastly, because each datacenter runs indepedently,
|
|
|
|
|
supporting multiple datacenters is no different than a single datacenter.
|
2014-02-08 00:41:03 +00:00
|
|
|
|
2014-04-10 20:51:08 +00:00
|
|
|
That said, Consul is not a replacement for configuration management tools.
|
2014-04-14 18:58:40 +00:00
|
|
|
These tools are still critical to setup applications and even to
|
2014-04-10 20:51:08 +00:00
|
|
|
configure Consul itself. Static provisioning is best managed
|
|
|
|
|
by existing tools, while dynamic state and discovery is better managed by
|
|
|
|
|
Consul. The separation of configuration management and cluster management
|
|
|
|
|
also has a number of advantageous side effects: Chef recipes and Puppet manifests
|
|
|
|
|
become simpler without global state, periodic runs are no longer required for service
|
|
|
|
|
or configuration changes, and the infrastructure can become immutable since config management
|
|
|
|
|
runs require no global state.
|
