2014-02-08 00:41:03 +00:00
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---
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2020-04-07 18:55:19 +00:00
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layout: intro
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2020-04-06 20:27:35 +00:00
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page_title: 'Consul vs. Chef, Puppet, etc.'
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2020-04-07 18:55:19 +00:00
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sidebar_title: 'Chef, Puppet, etc.'
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description: >-
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It is not uncommon to find people using Chef, Puppet, and other configuration
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management tools to build service discovery mechanisms. This is usually done
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by querying global state to construct configuration files on each node during
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a periodic convergence run.
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2014-02-08 00:41:03 +00:00
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---
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2014-04-10 20:51:08 +00:00
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# Consul vs. Chef, Puppet, etc.
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2014-02-08 00:41:03 +00:00
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2014-04-10 20:51:08 +00:00
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It is not uncommon to find people using Chef, Puppet, and other configuration
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management tools to build service discovery mechanisms. This is usually
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done by querying global state to construct configuration files on each
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2014-04-14 18:53:29 +00:00
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node during a periodic convergence run.
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Unfortunately, this approach has
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2015-03-06 23:08:35 +00:00
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a number of pitfalls. The configuration information is static
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2014-04-10 20:51:08 +00:00
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and cannot update any more frequently than convergence runs. Generally this
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is on the interval of many minutes or hours. Additionally, there is no
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2015-03-06 23:08:35 +00:00
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mechanism to incorporate the system state in the configuration: nodes which
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2014-04-10 20:51:08 +00:00
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are unhealthy may receive traffic exacerbating issues further. Using this
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approach also makes supporting multiple datacenters challenging as a central
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group of servers must manage all datacenters.
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2014-02-08 00:41:03 +00:00
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2014-04-10 20:51:08 +00:00
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Consul is designed specifically as a service discovery tool. As such,
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it is much more dynamic and responsive to the state of the cluster. Nodes
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can register and deregister the services they provide, enabling dependent
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applications and services to rapidly discover all providers. By using the
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2014-04-16 03:17:00 +00:00
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integrated health checking, Consul can route traffic away from unhealthy
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nodes, allowing systems and services to gracefully recover. Static configuration
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2014-04-17 20:18:16 +00:00
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that may be provided by configuration management tools can be moved into the
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2014-04-10 20:51:08 +00:00
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dynamic key/value store. This allows application configuration to be updated
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2014-11-05 04:01:45 +00:00
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without a slow convergence run. Lastly, because each datacenter runs independently,
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2014-04-10 20:51:08 +00:00
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supporting multiple datacenters is no different than a single datacenter.
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2014-02-08 00:41:03 +00:00
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2014-04-10 20:51:08 +00:00
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That said, Consul is not a replacement for configuration management tools.
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2015-03-06 23:08:35 +00:00
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These tools are still critical to set up applications, including Consul itself.
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Static provisioning is best managed by existing tools while dynamic state and
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discovery is better managed by Consul. The separation of configuration management
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and cluster management also has a number of advantageous side effects: Chef recipes
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and Puppet manifests become simpler without global state, periodic runs are no longer
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required for service or configuration changes, and the infrastructure can become
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immutable since config management runs require no global state.
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