Don't repeat yourself principle

As explained in Effective Platform Engineering

The DRY principle is the practice of avoiding duplicated knowledge or logic by maintaining a single authoritative representation.

The DRY principle keeps knowledge and logic in one authoritative representation instead of duplicating it across infrastructure, credentials, environments, or pipelines. section 6.3.3

Apply DRY by:

• Pulling secrets from a secrets manager when needed rather than copying them into pipeline-tool environment stores. section 6.3.3
• Sharing infrastructure code across environments and expressing differences through configuration parameters such as tfvars. section 6.3.3
• Keeping pipelines focused on ordering while reusable, versioned scripts or pipeline libraries contain shared logic. section 6.3.3

Environment-specific infrastructure

Instead of maintaining separate infrastructure folders or long-lived branches for each environment, reuse the same code and supply environment-specific parameters. section 6.3.3

Figure 6.10 Well-architected Infrastructure-as-code pipelines are no different from well-architected regular software pipelines. This is why we prefer the term “software-defined infrastructure” to differentiate between simply using an infrastructure-as-code (IaC) framework like Terraform and the software engineering practices that are a part of sustainable, high-quality software developer lifecycle management of an engineering platform product.

Relates DRY infrastructure practices to software-defined infrastructure and well-architected delivery pipelines. section 6.3.3

How Effective Platform Engineering covers it

How deep it goes

Explains practical implementation patterns and consequences, but stops short of broader theoretical treatment.

Examples

Uses secrets-manager lookups, tfvars-based environments, CircleCI orbs, shell-script libraries, and namespace-level pipelines.

What it assumes

Assumes familiarity with infrastructure code, deployment pipelines, environment configuration, and secrets managers.

What you can do after

Configure shared infrastructure and pipeline logic while limiting environment-specific differences to parameters and protecting credential rotation.

How it connects

Connects infrastructure as code with secrets management, environment configuration, reusable pipeline code, and software-defined infrastructure.

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Related concepts

• code duplicationaddressed by · Code duplication is the presence of equivalent or substantially similar source code or implementation logic in multiple locations within a software system.
• inheritanceused by · Inheritance is a mechanism by which a child type or element receives properties, values, or behavior from a parent, subject to system rules and possible overrides.
• decouplingaddresses · Decoupling is the design practice of reducing direct dependencies between software components so they can change, operate, or evolve more independently.
• moduleaddressed by · A module is a distinct, bounded software unit that groups related code or functionality and provides an organizational or interaction boundary within a larger system.
• functionuses · A function is a callable program unit that performs an operation, may accept inputs, and can produce a result or side effect.

This explainer was generated by Manning's knowledge graph from the text of Effective Platform Engineering. The section links point to the parts of the book it draws on.