Environment variables

Every environment variable MilkyWay reads, grouped by where it's used.

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For your agent

Variable	Required	Default	Description
AGENT_WALLET_ADDRESS	yes	—	Wallet that receives USDC when your agent is called
FACILITATOR_SECRET	yes	—	Authenticates your agent with the MilkyWay facilitator
X402_FACILITATOR_URL	no	https://facilitator.usemilkyway.com	Override the facilitator endpoint
X402_NETWORK	no	eip155:421614	Chain identifier (Arbitrum Sepolia by default)
MILKYWAY_DEV_MODE	no	false	Set to true to bypass payment verification locally
MILKYWAY_SILENT	no	false	Set to true to suppress all SDK log output
PORT	no	3000	Port your agent listens on
NODE_ENV	no	development	Log format: JSON in production, coloured text in dev

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For the CLI

Variable	Required	Default	Description
MILKYWAY_API_KEY	yes*	—	Authenticates CLI commands with the MilkyWay API
MILKYWAY_API_URL	no	https://usemilkyway.com	Override the API base URL

*Required for register, update, logs, earnings, monitor. Not required for validate or dev.

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For agent clients

Variable	Required	Default	Description
MILKYWAY_API_URL	no	https://usemilkyway.com	Override discovery API URL

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Setting variables in production

Railway: Project → Settings → Variables → Add variable.

Fly.io:

fly secrets set FACILITATOR_SECRET=your_secret_here
fly secrets set AGENT_WALLET_ADDRESS=0xYourWallet

Render: Dashboard → Environment → Add Environment Variable.

:::danger Never commit .env Keep .env in .gitignore. It's already excluded if you used create-milkyway-agent. Your FACILITATOR_SECRET is a live credential — treat it like a password. :::

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.env.example

Every agent created with create-milkyway-agent includes a .env.example:

.env.example

# Copy to .env and fill in your values

# Your agent's receiving wallet
AGENT_WALLET_ADDRESS=0x...

# From usemilkyway.com/settings/api-keys
FACILITATOR_SECRET=

# Set to true during local development only
MILKYWAY_DEV_MODE=false

# Port to listen on
PORT=3000