Keep your configs for each environment
The app's configuration is everything that may vary between environments. This includes:
- System resources like databases, Memcached, and backing services;
- Credentials for external services such as Amazon S3 or Twitter;
- Environment-specific values such as the hostname.
The Twelve-Factor methodology strongly advocates for
separating configuration from the code. This is primarily
because configuration values may differ between environments
while the code remains constant. A useful way to determine if
configurations are properly extracted from the code is by
considering the scenario of making the codebase open source.
If the credentials need to be managed, the configurations
might be compromised.
Another approach involves using configuration files not
included in the version control system, such as
'config/database.yml' in Rails. While this is a significant
improvement, it is not recommended because there's a risk of
accidentally pushing these files. Additionally, configuration
files often scatter across different locations, making
maintenance challenging. Moreover, these config files tend to
be specific to a particular language or framework.
Another practice to avoid is grouping configurations into
environment-specific sets. Apps tend to categorize
configurations into named groups for different environments.
However, this method doesn't scale well. As the project
expands, developers might introduce their own custom
environments, leading to an explosion of configurations that
complicate deployment management.
The Twelve-Factor methodology suggests storing
configurations in environment variables. Environment
variables are easy to modify between deployments without
requiring changes to the code. They compel setting up
independent configurations for each deployment environment,
minimizing the chance of accidental check in the codebase
repository. They don't aggregate into 'environments' groups,
they are language- and OS-agnostic standards and provide a
scalable model as the app naturally expands to more
deployments.
This Twelve-Factor App post series is a means for me to consolidate the knowledge I've gained while studying these rules. Please feel free to visit [the site (https://12factor.net/) for more detailed explanations. That's all folks!
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