crap.env

Read-only access to environment variables.

Functions

crap.env.get(key)

Get the value of an environment variable.

Parameters:

• key (string) — Environment variable name.

Returns: string or nil — The value, or nil if the variable is not set.

local db_url = crap.env.get("CRAP_DATABASE_URL")
if db_url then
    crap.log.info("DB URL: " .. db_url)
end

-- Common pattern: env with fallback
local port = crap.env.get("CRAP_PORT") or "3000"

Allowed Prefixes

For security, crap.env.get() only allows access to environment variables with specific prefixes:

All other environment variables (e.g., PATH, HOME, DATABASE_URL, AWS_SECRET_ACCESS_KEY) return nil regardless of whether they are set. This prevents hooks from accidentally or maliciously reading sensitive system or infrastructure variables.

-- These work (if set):
crap.env.get("CRAP_API_TOKEN")   -- returns the value
crap.env.get("LUA_PATH")         -- returns the value

-- These always return nil:
crap.env.get("PATH")             -- nil
crap.env.get("HOME")             -- nil
crap.env.get("DATABASE_URL")     -- nil

Notes

• Available in both init.lua and hooks.
• Returns nil for unset variables and for variables with disallowed prefixes (never errors).
• Useful for reading secrets, feature flags, or deployment-specific values without hardcoding them in Lua files.
• To pass configuration to hooks, set environment variables with the CRAP_ prefix (e.g., CRAP_SMTP_HOST, CRAP_WEBHOOK_SECRET).