Configuring applications, services, and environments by modifying plain text files is a standard part of modern software development. Configuration as Code (CaC) takes this one step further by systematically generating, storing, and managing configuration files. CaC allows development teams to automate config management for their applications and environments while ensuring consistency and traceability throughout the development life cycle.

In DevOps terms, CaC means defining your configuration files in a source repository along with your code and tests. The idea is that instead of making changes by hand in a text file for every new deployment, you make those same changes programmatically in version control to avoid the risk of manual errors. This method adds more layers of security and automation to your development process.

In this article, you will learn what CaC is, how it works, and its value to DevOps teams. You will also explore how CaC relates to GitOps, how it applies to the CI/CD pipeline, and how it compares to Infrastructure as Code.

What is configuration?

Configuration is the set of standards, attributes, and settings of a system. Developers use configuration files to define the settings and parameters of their applications, infrastructure, and continuous integration pipelines.

App config

Application configuration includes a collection of settings that define how your application functions. Those settings allow you to change the behavior or functionality of your application. Modern programs have many distributed components hosted on the cloud and run on containers hosted in multiple regions or virtual machines. If you spread configuration settings across all the components, you risk facing complications when troubleshooting errors or during deployment. App configuration means storing and managing all your app settings from one secure central location.

Infrastructure config

Infrastructure configuration is the process of defining and configuring the physical and logical resources required to support an application. It includes all the steps you need to take, from choosing your hardware and software to installing and finally configuring them for your application to use.

Infrastructure configuration can affect everything from performance to reliability and scalability — all important things to consider when building applications.

Pipeline config

A CI/CD pipeline is a collection of containerization, source control, monitoring, configuration management, and build tools. These tools automate the build, test, and deployment processes for applications and infrastructure. Pipeline configuration refers to a set of instructions that describe how your automated processes should be executed, which are in turn affected by your application and infrastructure config. The instructions are contained in a pipeline configuration file written in YAML, JSON, XML, or other formats.

What is configuration as code?

Ordinarily, application code is committed to a version control repository. Configuration is stored outside this repository, and developers manually create and customize the configuration of each of their deployments.

CaC is different because the configuration settings — including resource provisioning and environmental settings — are defined in executable code instead. This means you treat configuration settings as you would the code (including maintaining the settings in version control) and manage your configuration files along with your code.

CaC works well as part of a CI/CD pipeline, automating many aspects and tasks related to infrastructure maintenance, provisioning, and software configuration. This automation supports devs by reducing the number of error-prone, time-consuming manual tasks they must perform.

Infrastructure as code vs configuration as code

Infrastructure as Code (IaC) is the practice of treating infrastructure as if it were software. When you treat your infrastructure as another application in your software stack, it means you can write code to describe how your infrastructure should look. You can automatically create or destroy infrastructure based on that description once it has been tested.

Both IaC and CaC automate the provisioning and configuration of your software, but they do it in different ways.

In IaC, you model your infrastructure in code so a machine can manage it. You write scripts that describe what you want your system to look like and how you want it configured before deploying it. IaC is often used to automate the deployment and configuration of physical and virtual servers.

In CaC, you model your application configuration before deploying it. When you push out new software configurations, your entire application configuration settings are updated without requiring manual intervention. CaC can be used for any application type, including containers and microservices.

IaC, CI/CD, and merge requests are core practices of GitOps. GitOps is a way of managing declarative infrastructure using Git as the single source of truth. With GitOps, infrastructure changes are a core component of the software integration and delivery process, and you can integrate them into the same CI/CD pipeline. This integration makes it easier to change configuration. All a developer needs to do is create and push the configuration changes to the source control repository. In this repo, the code is tested using CI/CD tools, and the change is applied to the underlying infrastructure.

Benefits of configuration as code for DevOps

Configuration as code offers a number of benefits for development teams:

  • Reduced risk of misconfiguration errors
  • Standardization of development processes
  • Increased visibility into and control over changes to apps and infrastructure

Avoid misconfiguration vulnerabilities

Often, the cause of an open-source software security incident can be traced to misconfiguration errors. The problem is rampant in large-scale cloud environments where thousands or even millions of instances need to be configured in exactly the right way. CaC helps reduce misconfiguration errors by enabling automation and promoting consistency and simplicity.

Automating routine processes reduces human error and frees up time for the development team to engage in more valuable tasks. CaC provides the ability to easily change out configurations across unique development, test, and production environments. Teams that use CaC can be confident that they are deploying their applications in the same way across all environments.

When all configurations are stored centrally, teams can easily see how their changes impact other areas of their infrastructure or application environment. This helps ensure that changes do not break anything on other servers or networks. When everything is described as code and automated, an explicit set of instructions controls everything, greatly reducing the risk of error when deploying changes.

Supporting the standardization of pipelines

With CaC, you can create pipelines that run the same script against all environments. This helps you ensure that all environments are running the same application version. Writing configuration as a source code supports your goal as you implement development best practices. You can optimize your configuration to suit best practices such as security scanning, code quality analysis, and parameterization.

If you maintain microservices, you can use CaC to verify that you have similar build plans. By implementing standard processes, you ensure that your microservices work together. You also have the chance to review and test configuration files and make sure they follow the set standards before committing them to the main branch.

Improving compliance and change management

CaC provides traceability between configuration items and associated policies. When configuration items must comply to regulations before they can be deployed into production, devs must have a way to document that process and prove that it happened. Traceability helps DevOps practitioners improve compliance and change management by providing a way to create policies that ensure the security and stability of your systems.

The oversight and compliance aspect of managing CaC is a key benefit to users. When you have a single repository of configuration artifacts, there is an audit trail at the point of change. This helps determine who made what change, what they changed, and when. Since changes can be tracked and audited through version control systems or other tracking mechanisms, they can be identified and traced back to their originator if there is a problem (accidental or malicious).

You can enforce compliance standards by defining them in your configuration files. Any changes in these files will be propogated across all environments unless explicitly overridden by a user or administrator. You can easily control changes made to the application over time by:

  • Defining the exact state of your infrastructure in the config code itself
  • Auditing all changes made to that application’s configuration file

These two processes create an auditable record of all changes made to the application. By identifying any mistakes or problems with an application’s configuration file over time, you maintain compliance with security standards and ensure that your applications function properly.


Implementing configuration as code into your development process can provide huge benefits for your development team. It automates the process of applying configurations across environments, making it easier to apply updates and make sure everything works together. Because it uses a single repository, changes are easy to manage and trace. Configuration as code is a powerful tool for managing and controling complex infrastructure and pipelines while improving the development and deployment of code. The result is the visibility and control you need to accelerate your development without sacrificing confidence in your deployments.

CircleCI makes it simple to implement a CaC approach for managing your pipelines, applications, and infrastructure. You can sign up for a free plan and start using CaC to make your development process more stable, secure, and compliant.