Reference

Configuration

Every environment variable the Pretend image reads.

Environment variables

Pass these with docker run -e NAME=value or an env file. None of them are required to start the container.

Variable	Default	What it does
`RESEND_API_KEY`	`re_local_dev_key`	The bearer token the API accepts. You can create more keys in the dashboard.
`DISABLE_LOGIN`	`false`	`true` opens the dashboard without signing in. Trusted machines only.
`ADMIN_USERNAME`	none	Dashboard login username.
`ADMIN_PASSWORD`	none	Dashboard login password, as a scrypt hash (see below).
`SESSION_SECRET`	none	Long random string that signs the session cookie. Required unless `DISABLE_LOGIN=true`.
`DATA_DIR`	`/app/.data`	Where the database and attachments are stored. Mount your volume here.
`RATE_LIMIT`	`false`	`true` applies Resend's limit of 10 requests per second, answering `429 rate_limit_exceeded`.
`DOMAIN_ENFORCEMENT`	`true`	`false` lets any sender domain send. See Differences from Resend.
`PORT`	`3000`	Port the server listens on inside the container.

Unless DISABLE_LOGIN=true, the dashboard asks for ADMIN_USERNAME and a password. Store the password as a scrypt hash, never in plain text. Generate one with the Node.js that ships in the image:

Terminal

docker run --rm a2coder/pretend node -e '
  const c = require("crypto"), salt = c.randomBytes(16).toString("hex");
  console.log("scrypt:" + salt + ":" + c.scryptSync(process.argv[1], salt, 64).toString("hex"));
' 'your-password'

Then pass the output as ADMIN_PASSWORD, along with a random SESSION_SECRET:

Terminal

docker run -d --name pretend -p 3000:3000 \
  -v pretend-data:/app/.data \
  -e ADMIN_USERNAME=admin \
  -e ADMIN_PASSWORD='scrypt:…' \
  -e SESSION_SECRET="$(openssl rand -hex 32)" \
  a2coder/pretend

warning

A new SESSION_SECRET signs everyone out. Keep the same value across restarts.

Image details

Based on node:22-slim and runs as a non-root user (uid 1001).
Exposes port 3000 and declares /app/.data as a volume.
Tags: latest, plus one per commit sha on main. Every tag passes the full compatibility suite before it is pushed.

Configuration

Environment variables

Dashboard login

Image details