Rules Reference

DCLint categorizes rules into several categories to help you ensure that your Docker Compose files meet specific standards.

In the tables below:

• 🔴 — Error. Indicates a critical issue. The exit code will be non-zero if this occurs.
• 🟡 — Warning. Indicates a non-critical issue. The exit code will remain zero.
• 🔧 — Auto-fixable. Issues reported by this rule are automatically fixable.
• ⚙️ — Configurable. Behavior of the rule can be adjusted using options.

Style

These rules enforce consistency in formatting and structure to ensure that your Docker Compose files are easy to read and maintain. They focus on best practices related to code style, such as proper ordering of fields and avoiding unnecessary complexity.

Name	Description
No Quotes In Volumes	Values in the volumes section should not be enclosed in quotes.	🟡 🔧
Service Dependencies Alphabetical Order	Services in the depends_on section should be sorted alphabetically.	🟡 🔧
Service Keys Order	Keys within each service should follow a specific order.	🟡 🔧 ⚙️
Service Ports Alphabetical Order	The list of ports in a service should be sorted alphabetically.	🟡 🔧
Services Alphabetical Order	Services should be sorted alphabetically.	🟡 🔧
Top Level Properties Order	Top-level properties should follow a specific order.	🟡 🔧 ⚙️

Security

Security rules focus on identifying potential vulnerabilities in your Docker Compose files. These rules help prevent common security risks, such as exposing sensitive data or using unsafe configurations.

Name	Description
No Duplicate Container Names	Container names must be unique to prevent conflicts and ensure proper container management.	🔴
No Duplicate Exported Ports	Exported ports must be unique to avoid conflicts.	🔴
No Unbound Port Interfaces	Exported ports must be bound to specific interfaces to avoid unintentional exposure.	🔴
Service Container Name Regex	Container names must match the pattern /^[a-zA-Z0-9][a-zA-Z0-9_.-]+$/u to comply with Docker naming conventions.	🔴
Service Image Require Explicit Tag	Services must use a specific image tag instead of "latest", "stable" or similar or no tag.	🔴 ⚙️

Best Practice

These rules enforce general Docker Compose best practices, guiding you towards configurations that are known to work well. They help avoid pitfalls and ensure your configurations are reliable and maintainable.

Name	Description
No Build And Image	Each service must use either build or image, not both.	🔴 ⚙️
No Version Field	The version field must be absent in the configuration.	🔴 🔧
Require Project Name Field	The name field should be included in the configuration.	🟡
Require Quotes In Ports	Ports in ports and expose sections should be enclosed in quotes.	🟡 🔧 ⚙️

Performance

Performance rules are designed to optimize the runtime behavior of your Docker Compose setup. They identify configurations that could negatively impact performance, such as inefficient resource usage or misconfigurations that may lead to slower application performance.

Name	Description