The Twelve-Factor App: Dev/prod parity

Keep development, staging, and production as similar as possible

Historically, significant disparities have existed between development and production environments, manifesting in several ways:

• The Time Gap: Code often takes days, weeks, or even months to reach production, whereas it should ideally be deployed within hours or minutes.
• The Personnel Gap: Developers create code while DevOps engineers handle deployment. Ideally, developers would be closely engaged in deploying and observing its behavior in the production environment.
• The Tools Gap: Local development setups might utilize stacks like Nginx, SQLite, and OS X, while production environments employ Apache, MySQL, and Linux. Let's keep development and production as similar as possible.

The Twelve-Factor app is engineered for continuous deployment, aiming to narrow the gap between these environments.

Developers adhering to the twelve-factor principles resist the temptation to use different backing services in development versus production. This stems from the appeal developers find in using lightweight services locally versus more robust ones in production. Discrepancies between these services often lead to minor incompatibilities, causing code that passed testing in dev or staging to fail in production. This discourages continuous deployment and results in considerable friction that incurs significant costs throughout an application's lifecycle. Additionally, modern packaging systems like Homebrew and apt-get have made installing and running modern backing services less challenging.

Many programming languages offer libraries that streamline access to backing services, providing adapters for various service types. For instance, ActiveRecord for Ruby/Rails includes database adapters such as MySQL, PostgreSQL, and SQLite. While adapters to different backing services simplify porting to new services, it's essential for all deployments (developer environments, staging, production) to use the same type and version of each backing service.

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 for more detailed explanations. That's all folks!