10 Python Config File Best Practices

Configuration files are an important part of any Python project. They help you keep your project settings in one place and allow you to change them easily.

However, there are some best practices you should follow when creating and using config files. In this article, we’ll go over 10 of the most important Python config file best practices. By following these best practices, you can make sure your config files are well organized, easy to use, and secure.

1. Use the ConfigParser module

The ConfigParser module is part of the standard library, so you don’t need to install anything to use it. It’s also easy to use. You can create a config file using a text editor like vim or gedit, and then read and write values using the ConfigParser API.

ConfigParser is also flexible. You can store different types of data in your config file, including integers, floats, booleans, and strings. This makes it easy to store complex data structures in your config file.

Finally, ConfigParser is portable. You can use it on any platform that supports Python, including Windows, Linux, and macOS.

2. Don’t store passwords in your config file

If someone were to gain access to your config file, they would then have access to any passwords that are stored in there. This could be disastrous if those passwords give access to sensitive data or systems.

A better approach is to store passwords in a separate, secure location, and then reference them in your config file. That way, even if someone did gain access to your config file, they wouldn’t be able to do anything with the passwords.

3. Store sensitive data outside of version control

When you store your config file in version control, anyone with access to the repository can see your sensitive data. This is a security risk, as someone could potentially misuse this information.

Instead, you should store your config file outside of version control, and only include the minimum amount of information necessary in the file. This way, only those who need to know the sensitive data will have access to it.

4. Make sure you have a default value for every option

Say you have a config file with two options, “foo” and “bar”. If the user doesn’t set a value for “foo”, your program will crash. But if they don’t set a value for “bar”, it will just use the default. So, by having defaults for all options, you make your program more robust and less likely to crash.

5. Keep it DRY: use variables to avoid duplication

Say you have a config file with two sections, each of which has three settings. One of the settings is common to both sections, and you want to set it to the same value in both cases.

If you duplicate the setting in both sections, then you have to remember to update both values if you ever need to change it. This violates the DRY principle, and can lead to errors and inconsistencies.

Instead, you can use a variable to store the common setting, and then reference that variable in both sections. This way, you only have to update the setting in one place, and you can be confident that it will be applied consistently in both sections.

6. Use environment variables when appropriate

Environment variables are a great way to store sensitive information, such as API keys, that you don’t want hard-coded into your config file. They also allow you to easily change the value of a variable without having to modify your code.

Additionally, environment variables are often used in conjunction with 12-factor app principles, which is a methodology for building scalable and resilient web applications.

7. Avoid hard-coding values

If you hard-code values into your config file, then you’re effectively creating a new config file every time you need to change those values. This can quickly become unmanageable, especially if you have multiple config files and/or a lot of values that need to be changed frequently.

Instead, you should use variables for all values that might need to be changed in the future. That way, you can simply update the value of the variable in one place, and it will be reflected everywhere else in the config file (and in any other config files that import that variable).

8. Consider using JSON instead of INI format

JSON is a lot more readable than INI files. It’s also easier to work with because it can be parsed into a dictionary data structure, which is much more convenient than working with INI files.

INI files are also more prone to errors because they’re not as strictly formatted as JSON files. This means that it’s easy to make a mistake when editing an INI file, which can lead to unexpected results.

Overall, JSON is a better choice for Python config files because it’s more readable, easier to work with, and less error-prone.

9. Consider using YAML instead of INI format

YAML is a superset of JSON, which means that any valid JSON file is also a valid YAML file. This makes it much easier to work with because you can use the same tools and libraries for both JSON and YAML.

YAML also has support for comments, which can be very useful when you need to document your config files.

INI files are also supported by Python, but they have some limitations. For example, INI files don’t support comments, and they’re not as widely used as YAML or JSON.

10. Use comments to explain what’s happening

As you start to write more complex code, it can be easy to forget what everything does. But if you take the time to add comments, it’ll be much easier to remember (or figure out) later on.

Plus, if you ever need to share your code with someone else, they’ll appreciate the extra effort. Comments are a courtesy that can save everyone a lot of time and frustration.