Auto-Generated Variables

When you create an app, Potions auto-generates environment variables so your Phoenix app can boot, connect to its database, and write persistent files without any manual configuration. These variables are marked with an auto badge to distinguish them from variables you add yourself.

The Variables

Variable	Default Value	Purpose
`SECRET_KEY_BASE`	Random 64-byte base64 string	Phoenix uses this to sign and encrypt sessions, cookies, and tokens
`DATABASE_URL`	`ecto://<user>:<pass>@localhost:5432/<db>`, or the external connection URL you pasted	PostgreSQL connection string for your app's dedicated database, or for the external database you connected. Encryption is set in your app's config; see Encrypting the connection. Not set for SQLite apps
`DATABASE_PATH`	`/opt/potions/<app>/db/<app>.sqlite3`	The SQLite database file, for apps created with SQLite on this server; what `mix phx.new --database sqlite3` reads. Replaces `DATABASE_URL`. See SQLite and Litestream
`PHX_HOST`	Your server's IP address	The hostname Phoenix uses for URL generation, websocket endpoints, and email links
`PHX_SERVER`	`true`	Tells Phoenix to start the HTTP server when the release boots
`PORT`	App's assigned port (e.g., `4000`)	The port your app listens on. Caddy reverse-proxies traffic from ports 80/443 to this port
`MIX_ENV`	`prod`	The Mix environment used during build and at runtime
`STORAGE_DIR`	`/opt/potions/<app>/storage`	A persistent directory for user uploads and other files that must survive deploys. See Persistent Storage

Apps on an external database whose host is reachable only over IPv6 also get ECTO_IPV6=true, set from the connection check.

The Environment tab showing auto-generated variables with the auto badge

Editing and Deleting Auto-Generated Variables

Most auto-generated variables are fully editable. You can change the value of any variable from the Environment tab, or delete it if your app doesn't need it.

PORT, STORAGE_DIR and DATABASE_PATH are exceptions - they're system-managed by Potions and appear with a lock icon instead of edit/delete buttons. The values are set automatically and can't be overridden. For apps on an external database, DATABASE_URL is locked too and managed on the Database tab.

Changes to environment variables take effect on the next deploy. They don't affect your currently running instance.

Variables Injected at Deploy Time

Potions also injects the following variable on every deploy. This is not stored with your app's variables and does not appear on the Environment tab.

Variable	Value
`POTIONS_COMMIT_SHA`	The full commit SHA of the deploy currently running

Point your error tracker at it to see which deploy an error came from. See Deploy Metadata for setup with AppSignal, Sentry, and others.

Things to Know

PHX_HOST updates automatically with domains. When you add your first custom domain, Potions updates PHX_HOST to match. If you delete the primary domain, Potions reverts PHX_HOST to the server IP. You can also change it manually at any time. See Adding a Custom Domain for details.
All values are encrypted at rest. Potions uses AES-256-GCM encryption for every variable, not only auto-generated ones.
Deleting DATABASE_URL won't delete your database. The PostgreSQL database and user continue to exist on the server. The variable is only the connection string. For external databases, change it on the Database tab; see External Databases.
Your variables are excluded from build logs. Potions redacts sensitive values from build output so credentials never appear in deployment logs.