Configuration and environment

Use this skill when

• The server will not start because of missing or invalid configuration.
• Bootstrapping a new deployment environment and wiring real env vars or secrets.
• Behaviour differs between environments and the question is whether env loading is the cause.
• The main problem is repo-owned runtime config drift, such as a missing Cloudflare Worker binding in wrangler.toml, wrangler.json, or wrangler.jsonc, without schema or migration work.

Do not use this skill when

• The deeper concern is auth or sensitive-data exposure (use security-basics).
• The blocker is standing up a multi-service stack rather than env loading itself (use docker-compose-dev).

Inputs to gather

• The authoritative list of required and optional variables (usually .env.example or README).
• The runtime platform (shell, CI, container) supplying env vars and whether .env is used.
• Any repo-owned runtime config that supplies bindings or non-secret settings, such as wrangler.toml, wrangler.json, or wrangler.jsonc.
• The health-check endpoint or equivalent runtime check used to confirm a good startup.

First move

• Compare real env vars and any .env against .env.example or the repo's config loader, then inspect runtime config files like wrangler.* for missing bindings or drift before starting the service and hitting /health or the closest existing startup check.

Catalog position

Keep this easy to reach for startup failures, env drift, and deployment/config debugging.

• Prefer security-basics when the question is primarily about auth, sensitive exposure, or request-handling safety.
• Prefer docker-compose-dev when the blocker is bringing up a multi-service stack rather than validating env loading itself.
• Prefer cloudflare-d1-migrations when the task changes D1 schema, migration files, or schema state rather than only fixing the Worker binding/config contract.
• Pair this with rpi-workflow only when configuration work is part of a larger multi-phase change.

Loading priority (highest to lowest)

1. Real environment variables (shell, CI secrets, runtime platform)
2. .env file (local developer override)
3. .env.example (documentation only — never loaded at runtime)

Setup

cp .env.example .env     # start from the documented template
# edit .env with real values for your environment

Never commit .env. Add it to .gitignore.

Variable categories

Check .env.example or project README for authoritative var names. Common categories:

Category	Examples
Database	DATABASE_URL — connection string
Auth	Secret key / bearer token
Origins/CORS	ALLOWED_ORIGINS — comma-separated list
TLS/Cookies	SECURE_COOKIES, COOKIE_DOMAIN
Feature flags	Enable/disable optional subsystems

Required variables cause startup failure. Optional variables activate features.

Security constraints

• Production must use real env vars or a secrets manager — not .env files.
• Never set ALLOWED_ORIGINS=* when credentials or cookies are involved — use explicit origins.
• Enable secure cookies when behind HTTPS.
• Protect sensitive endpoints (metrics, admin) behind auth — do not leave them open by default.
• Never hardcode secrets in source code.

Validation

make build && ./bin/server   # or equivalent start command
curl http://localhost:<PORT>/health

A healthy response confirms the configuration was accepted.

Anti-patterns

• Hardcoding secrets in source code or test fixtures
• Using .env in production or CI
• ALLOWED_ORIGINS=* with cookie/credential-based auth
• Silently ignoring missing required config — always fail fast at startup

Guardrails

• Production must use real env vars or a secrets manager — never .env files.
• Required variables must fail the server at startup, not silently at request time.
• Never commit .env; only .env.example belongs in source.
• Never hardcode secrets in source code or test fixtures.

Support files

• Read references/examples.md when you need concrete user utterances, expected behaviour, or a model answer shape to mirror.
• Read references/edge-cases.md when the request is a near miss, partially matches this skill, or the first attempt fails.
• Run scripts/check-config.sh --help when you want a repeatable environment/configuration check.