8 best practices for configuration file management

What are configuration files?

Configuration files contain settings, options, values and parameters used by OSes, applications and network devices. These systems reference the files and apply the settings. Some configuration files are simple and application-specific. Others govern the system's functionality or maintain application versions.

Configuration files maintain an efficient environment. Modern CI/CD and DevOps approaches emphasize automation, scaling and version control.

In the past, admins used informal methods to maintain master copies, relying on replication tools, like rsync, to deploy the files and set up simple automation processes using SSH and Bash scripts. Today's diverse environments demand a better way to maintain configuration files.

Best practices

The following best practices should guide admins and programmers through choosing and managing configuration files.

Understand common errors

Mitigate the following common errors to start work with configuration files:

• Avoid default security settings. Carefully analyze whether default settings are acceptable for your environment.
• Avoid hardcoded names and references. Resource names may change, especially in a scalable cloud environment. Avoid referencing systems by names or other potentially changeable identifiers.
• Avoid syntax errors. Simple typos in configuration files may lead to complications. Use tools and review processes to catch typos as soon as possible.
• Eliminate permissions issues. Review access requirements for service accounts, SSH connections and other automation tools that help maintain configuration files.
• Verify sufficient logging. Configuration files may define log file settings, including severity levels and retention policies. Be sure these align with your security requirements.

Plan for success

Plan for configuration file management by evaluating system roles, human interactions, change management requirements and technologies. Choose the right tool, and assign it to the right job.

Clearly define what the configuration files should manage and what platforms they apply to. Organizations might have a wide variety of devices to manage, so plan for centralized control. Maintain current documentation so that everyone understands what configuration files exist and what settings they apply.

Set a goal

Goals should include availability, consistency and efficiency. Maintain configuration files, and carefully control changes to them to keep devices secure and available. Careful management also supports quick and trustworthy configuration changes.

Establish a single source of truth

The single source of truth, in this case, refers to a repository that holds the definitive version of all configuration files. This repository contains the only valid versions of configuration files, and all configuration files originate from it. The concept extends to each configuration file maintained in the repository. Carefully control a single master copy of each configuration file in this repository.

Centralization makes it easier to understand and maintain the files. The goal is to avoid a situation where some network administrators pull router configuration files from one repository and other admins pull from another.

Automate whenever possible

Today's IT environments emphasize automation. It reduces human error caused by manual processes that may not be applied consistently or contain mistakes. These mistakes can be catastrophic if they block legitimate network traffic or disable essential services.

Automated systems do not forget devices. Updated configuration files are delivered to all available devices, ensuring consistent settings. Automation also accounts for autoscaling situations in cloud-based environments where multiple systems can be built or torn down.

Use version control

Effective version control is essential to managing configuration files. Many administrators are likely to be involved with maintaining systems and network devices with the programmers. Collaborative efforts require some way of controlling definitive versions.

The standard version control mechanism is Git. Git environments can be deployed internally if internet security is a concern. No matter what version control is in use, everyone must use it. The version management system controls configuration files. Automation tools are available for version control mechanisms, but ensure they are compatible.

Standardize configuration file editing tools

Supporting tools maintain configuration files. Begin with standardized applications for editing configuration files. These may be simple tools, like the Vim editor, or more complicated utilities, like Microsoft's Visual Studio Code. Many of these utilities include features like tab completion, highlighting and syntax checking. Ensure all administrators use the same editors.

Use a standard set of software linters to check configuration code. Linters check for errors, maintain readability, look for security complications and optimize code.

Create configuration file templates that include comments and other elements that provide consistency. Some editing tools can enforce these standards and formatting.

Test configuration files

It is vital to test configuration files, as demonstrated by the 2024 CrowdStrike debacle with Windows. Whether tests are done in development environments or with automated tools, it's critical to ensure any changes to the configuration files do not introduce complications or result in downtime.

Consider the following types of testing:

• Integration testing. This method ensures the file loads correctly and the application works as expected.
• Configuration validation. This approach checks the syntax and structure of configuration files to avoid typos and other basic errors.

Automated testing procedures and tool sets that check syntax during the editing process help maintain consistent and reliable configuration files. Use automated testing whenever possible.

Configuration file languages

Modern configuration files offer more flexibility than older INI or similar files. They use a strong format with strict requirements that ensure consistency and readability. Some configuration file formats include JSON, YAML and XML.

Configuration file formats might be dictated by the automation and configuration management tools the company selects. However, standardizing a specific file structure keeps files consistent.

Some configuration management tools

Many tools manage and deploy configuration files. These tools specialize in maintaining infrastructure-as-code environments and establishing automated configuration management.

Configuration management options include the following:

• Ansible.
• Chef.
• Puppet.
• SaltStack.
• Terraform.

Damon Garn owns Cogspinner Coaction and provides freelance IT writing and editing services. He has written multiple CompTIA study guides, including the Linux+, Cloud Essentials+ and Server+ guides, and contributes extensively to TechTarget Editorial and CompTIA Blogs.