Architecture Decision Record
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Configuration fo environment variable

Wetin Dey Inside:

Summary

Issue

We want make our applications fit configure beyond artifacts/binaries/source, so one build fit behave different depending on di deployment environment wey e dey.

  • To do dis, we want use environment variable configuration.

  • We want manage di configuration with files wey we fit version control.

  • We want provide some developer experience ergonomics, like to know wetin fit configure and any relevant defaults.

Decision

We decide on .env files with related default file and schema file.

Status

Decided. We open to consider new capabilities as dem come up.

Details

Wetin We Assume

We favor to separate di application code and environment code. We assume say di app need to work different for different environments, like development environment, test environment, demo environment, production environment, etc.

We favor di industry practice of "12 factor app" and even more di related practice of "15 factor app".

Many of our previous projects don use di convention of .env file or similar .env directory. Typical practice dey to keep dem out of version control, and instead use some other way to deploy dem, version dem, and manage dem.

Wetin Dey Limit Us

We want keep secrets out of our source code management (SCM) version control system (VCS).

We want aim for compatibility with popular software frameworks and libraries. For example, Node get module "dotenv" to read environment variable configuration.

Positions

We consider few approaches:

  • Store config inside di app like for file config.js file.

  • Store config inside di environment like for file .env.

  • Fetch config from known location like license server.

Argument

We select di approach of file .env because:

  • E popular including among experts.

  • E follow di pattern of .env files wey our teams don use successfully many times for many projects.

  • E simple. Notably, we dey fine for now with di significant trade-offs wey we see, like lack of audit capabilities compared to approach of license server.

Wetin E Mean

We need to figure out way to separate environment variable configuration wey public from any secrets management.

Wetin Join

Decision Dem Wey Join

We expect all our applications to use dis approach.

We go plan to upgrade any of our applications wey use less-capable approach, like hardcoding for binary or for source code.

We go keep as-is any of our applications wey use more-capable approach, like licensing server.

Requirement Dem Wey Join

We go add devops capabilities for di files, including hooks, tests, and continuous integration.

We need to train all developer teammates on dis decision.

Artifact Dem Wey Join

Each area where we deploy go need im own .env file and related files.

Principle Dem Wey Join

Easily reversible.

Notes

Example file .env:

NAME=Alice Anderson
EMAIL=alice@example.com

Example file .env.defaults:

NAME=Joe Doe
EMAIL=joe@example.com

Example file .env.schema with just di keys:

NAME
EMAIL