@justsml/auto-config
v1.1.3
Published
A Unified Config & Arguments Library for Node.js. Featuring support for environment variables, command line arguments, and JSON files!
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@justsml/auto-config
Intro
A Unified Config & Arguments Library for Node.js!
Featuring support for environment variables, command line arguments, and (soon) JSON/YAML/INI files!
Why
There are so many config libraries, do we really need another??? Well, possibly!
No existing library I tried met my requirements.
My goals & requirements include:
- Enable dynamic app config. See '12 Factor App' on Config
- TypeScript support.
- Portable pattern (not filesystem-locked, browser support.)
- Simple, memorable & terse config format.
Table of Contents
Install
npm install @justsml/auto-config
yarn add @justsml/auto-config
Example
// `./src/config.ts`
import { autoConfig } from '@justsml/auto-config';
export default autoConfig({
databaseUrl: {
help: 'The Postgres connection string.',
args: ['--databaseUrl', '--db', 'DATABASE_URL'],
required: true,
},
port: {
help: 'The port to start server on.',
args: ['--port', '-p', 'PORT'],
type: 'number',
required: true,
},
debugMode: {
help: 'Debug mode.',
args: ['--debug', '-D'],
type: 'boolean',
default: false,
},
});
// `./src/app.js`
import config from './config';
console.log(config);
Configuring your App Dynamically
Command line arguments
node ./src/app.js \
--port 8080 \
--databaseUrl 'postgres://localhost/postgres' \
--debug
# { port: 8080, databaseUrl: 'postgres://localhost/postgres', debug: true }
Mix of environment and command arguments
DATABASE_URL=postgres://localhost/postgres \
node ./src/app.js \
--port 8080 \
--debug
# { port: 8080, databaseUrl: 'postgres://localhost/postgres', debug: true }
Single-letter flag arguments
node ./src/app.js \
-D \
--port 8080 \
--databaseUrl 'postgres://localhost/postgres'
# { port: 8080, databaseUrl: 'postgres://localhost/postgres', debug: true }
Error on required fields
node ./src/app.js \
--port 8080
# Error: databaseUrl is required.
CLI Help Output
node ./src/app.js --help
╭───────────────────────────┬────────────────────────────────────────────┬──────────────────────────────────────────────────────────╮
│ │ │ │
│ Name │ Help │ CLI Args, Env Name(s) │
│ │ │ │
├───────────────────────────┼────────────────────────────────────────────┼──────────────────────────────────────────────────────────┤
│databaseUrl* │The Postgres connection string. │--databaseUrl, DATABASE_URI, DATABASE_URL │
├───────────────────────────┼────────────────────────────────────────────┼──────────────────────────────────────────────────────────┤
│port* │The port to serve content from. │-p, --port │
├───────────────────────────┼────────────────────────────────────────────┼──────────────────────────────────────────────────────────┤
│[debugMode] = false │Debug mode. │-D, --debug │
├───────────────────────────┼────────────────────────────────────────────┼──────────────────────────────────────────────────────────┤
│help │Show this help. │--help │
├───────────────────────────┼────────────────────────────────────────────┼──────────────────────────────────────────────────────────┤
│version │Show the current version. │--version │
╰───────────────────────────┴────────────────────────────────────────────┴──────────────────────────────────────────────────────────╯
TODO
- [ ] Enum support.
- [ ] Inverting boolean flags with
--no-debug
versus--debug
. - [x] Auto
--help
output. - [x]
--version
output. - [x]
default
values. - [x]
required
values. - [x] Zod validators for
optional
,min
,max
,gt
,gte
,lt
,lte
.
Credit and References
Projects researched, with any notes on why it wasn't a good fit.
- yargs - like the fluent API, and command syntax. Could use as base library. Env vars could be handled via
default
helper function to check for env keys. Or we could transform yargs config into overlapping format. - commander - like the many ways to configure arguments. Could probably be used as underlying library, however initial attempt was slower than starting from scratch.
- cosmiconfig - focused too much on disk-backed config.
- rc - focused on 'magically' locating disk-backed config.
- node-convict - great pattern, but limited TypeScript support.
- nconf - setter & getter, plus the hierarchy adds extra layers.
- conf - too opinionated (writing to disk.) Interesting use of JSON Schemas, Versioning, and Migrations.
- gluegun - great design, focused on opinionated design of CLI apps though.
- configstore - replaced by conf.