Configuration management tools vs automation tools

What’s the difference between configuration management (CM) tools and automation tools? John Ray explains…

Given their common goals of improving system efficiency and keeping applications updated, it might be easy to confuse automation tools, like Ansible, with CM systems, like Chef and Puppet. The two are often considered one in the same since they both serve critical roles in infrastructure automation and application orchestration, but it’s important to distinguish the fine line between CM and automation, and choose the right tool for the job.

What’s the difference?

There are two main differences between automation tools and configuration management tools. One is idempotency, and the other is the ability to track changes and node status.

Idempotency is the idea that running a piece of code over and over again won’t change the system past the first time. Automation tools like Ansible help you automate mundane tasks – but they aren’t idempotent by default, and require the user to code for idempotency. Consider a piece of code that adds an entry to the /etc/hosts file. A CM tool like Chef makes the entry one time, no matter how many times you run the client. A non idempotent script would add the entry over and over again, creating a mess at best and causing serious system problems at worst. Automation tools might make repetitive, everyday tasks a breeze, but in addition to not being idempotent, they also lack something that their bigger configuration management siblings all have. A method of keeping records of nodes and actions.

With the added power of a database to track changes, configuration management tools have the ability to look at trends, create detailed reports, and act as an early warning against system instability. They can also use this data to further inform their automation scripts, creating powerful mechanisms for service discovery.

Final thoughts

If your IT team is looking for a resource without the dynamic range of services that automation offers, a CM tool like Puppet might suffice. But it’s certainly worth looking into an integrated CM service like Chef. Its flexibility, CM and automation interaction, and ever-evolving accommodations make it a valuable asset to any IT team.

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