impl

Multi-Environment Deployment Strategy Management.

This module provides a comprehensive framework for managing multi-environment deployment strategies in Python applications. It enables developers to define custom environment enumerations and automatically detect the current runtime environment based on various runtime contexts and environment variables.

• 🔧 devops: Foundation environment for building code, conducting unit tests,

  and creating artifacts. Not used for application deployment.

• 🧰 sbx101, 102, 103: Sandbox environments for temporary development/testing,

  allowing multiple engineers to work on different branches concurrently without interference. Named with convention ‘sbx-${number}’ for easy provisioning/destruction.

• 💻 dev: Development environment for active development work.

• 🧪 tst: Durable test environment for integration and end-to-end testing,

  including high-risk tests like load/stress testing that could compromise system integrity.

• 🎸 stg: Staging environment mirroring production conditions for QA testing

  under realistic workloads. Outputs captured for analysis, not visible to end users.

• 👮 qa: Isolated environment allowing external QA collaborators to work on

  testing without affecting other environments or having access to sensitive systems.

• 🚦 preprd: Pre-production environment with production data but isolated from

  end user traffic, enabling high-risk changes and debugging with real data.

• 🏭 prd: Production environment serving end-users directly, with immutable

  artifact versioning for quick rollbacks.

exception which_env.impl.EnvNameValidationError

Raised when an environment name fails validation rules.

which_env.impl.validate_env_name(env_name: str)

Validate environment name against naming conventions.

Environment names must follow specific naming conventions:

• First character must be lowercase letter (a-z)

• Remaining characters can be lowercase letters or digits (a-z, 0-9)

• No special characters, spaces, or uppercase letters allowed

Parameters:

env_name – The environment name to validate

Raises:

EnvNameValidationError – If the environment name violates naming rules

class which_env.impl.CommonEnvNameEnum(value, names=None, *, module=None, qualname=None, type=None, start=1, boundary=None)

Standard environment name enumeration following industry best practices.

Provides consistent naming for common deployment environments used across software development lifecycles. These names follow the aws_ops_alpha pattern and are widely recognized in DevOps practices.

class which_env.impl.BaseEnvNameEnum(value, names=None, *, module=None, qualname=None, type=None, start=1, boundary=None)

Base class for defining custom environment name enumerations.

This class provides the foundation for creating project-specific environment enumerations while enforcing validation rules and providing utility methods. All custom environment enumerations must inherit from this class and follow the established patterns.

Required Environments:

Every custom enumeration must define at least three environments:

1. devops: Build and CI/CD environment (not for deployment)

2. dev: Development environment for active coding and testing

3. prd: Production environment for live user traffic

1. Validation of environment names.

2. Iteration over all available environment names.

To define your own environment name enumerations class, you need to subclass this class. However, there are some restrictions:

1. You cannot create a “devops” environment as it does not qualify as a workload environment. 1. You must include at least a “devops”, a “dev” (development) environment

and a “prd” (production) environment.

2. environment name has to be lower case, without

Validation Rules:

• Environment names must be lowercase with digits only (a-z, 0-9)

• First character must be a letter (a-z)

• No special characters, spaces, or uppercase letters

• Must include required environments (devops, dev, prd)

Usage Pattern:

1. Inherit from BaseEnvNameEnum

2. Define environment constants

3. Call validate() to ensure compliance

4. Use with detect_current_env() for runtime detection

classmethod validate()

Validate that the enumeration follows required patterns and naming rules.

Ensures the custom enumeration includes all required environments and that all environment names follow the established naming conventions. This method should be called after defining a custom enumeration to catch configuration errors early.

Validation Checks:

1. Required Environments: Must include ‘devops’, ‘dev’, and ‘prd’

2. Naming Convention: All names must follow validate_env_name() rules

classmethod get_devops()

Get the DevOps environment reference from the enumeration.

classmethod get_dev()

Get the Development environment reference from the enumeration.

classmethod get_prd()

Get the Production environment reference from the enumeration.

property emoji: str

et the emoji representation of this environment.

Provides a visual identifier for the environment that can be used in logging, user interfaces, or documentation to quickly identify the environment context.

which_env.impl.detect_current_env(env_name_enum_class: BaseEnvNameEnum | Type[BaseEnvNameEnum], runtime: Runtime | None = None) → str

Intelligently detect the current environment name based on runtime context.

This function implements a sophisticated environment detection strategy that adapts to different runtime contexts (local development, CI/CD, production apps) and provides sensible defaults while allowing explicit overrides.

Detection Strategy:

The detection logic follows a priority-based approach designed to handle common deployment patterns while maintaining flexibility:

1. Local Development Runtime (laptop, workstation):

   • Default: ‘dev’ environment (assumption: developers usually work in dev)

   • Override: USER_ENV_NAME environment variable allows switching contexts

   • Use Case: Developer testing different environment configurations locally

2. CI/CD Runtime (GitHub Actions, Jenkins, etc.):

   • Priority 1: USER_ENV_NAME (manual override for special cases)

   • Priority 2: ENV_NAME (standard CI environment specification)

   • Use Case: Automated deployments to different target environments

3. Application Runtime (deployed applications):

   • Priority 1: USER_ENV_NAME (operational override capability)

   • Priority 2: ENV_NAME (deployment-time environment specification)

   • Use Case: Production applications that need environment context

Design Rationale:

Why Two Environment Variables?

• ENV_NAME: System-level environment specification set by deployment

  infrastructure, CI/CD pipelines, or container orchestration. This represents the “official” environment designation.

• USER_ENV_NAME: User-level override for operational flexibility.

  Allows developers, DevOps engineers, or applications to temporarily override the environment context without changing infrastructure.

Why Default to ‘dev’ Locally?

• Developer Experience: Most local development work happens in dev context

• Safety: Prevents accidental production operations from local machines

• Flexibility: Easy override with USER_ENV_NAME when needed

Parameters:

• runtime – Runtime context detector from which_runtime package. Determines whether code is running locally, in CI, or in production.

• env_name_enum_class – Custom environment enumeration class inheriting from BaseEnvNameEnum. Defines valid environments for the project.