diff --git a/docs/ENV-VARS.md b/docs/ENV-VARS.md
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+# Useful Environment Variables
+
+Plume relies on some environment variables for some configuration options. You can either set them before
+starting the app with `cargo run` or write them in a `.env` file to have automatically loaded.
+
+Here are the variables that Plume uses:
+
+- `BASE_URL`: the domain name, or IP and port on which Plume is listening. It is used in all federation-related code.
+- `DB_URL`: the URL of the PostgreSQL database, used by Plume (`postgres://plume:plume@localhost/plume` by default).
+- `POSTGRES_USER`: if you just want to use a different PostgreSQL user name, and keep the rest of the default URL.
+- `POSTGRES_PASSWORD`: same as `POSTGRES_USER`, but for the password.
+- `USE_HTTPS`: if it is `0`, federation and medias will be using HTTP by default (`1` by default).
+- `ROCKET_ADDRESS`: the adress on which Plume should listen (`0.0.0.0` by default).
+- `ROCKET_PORT`: the port on which Plume should listen ([`7878` by default](https://twitter.com/ag_dubs/status/852559264510070784))
+- `ROCKET_SECRET_KEY`: key used to sign private cookies and for CSRF protection. If it is not set, it will be regenerated everytime you restart Plume,
+meaning that all your users will get disconnected. You can generate one with `openssl rand -base64 32`.
+
+## Diesel
+
+Diesel, the tool we use to run migrations may be configured with the `DATABASE_URL` which should contain the URL of the
+PostgreSQL database. Otherwise, you can specify `--database-url YOUR-URL` everytime you run a `diesel` command.
+
diff --git a/docs/README.md b/docs/README.md
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+++ b/docs/README.md
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 - [Installing Plume (for development or production)](INSTALL.md)
 - [Updating your instance](UPDATE.md)
+- [Useful Environment Variables](ENV-VARS.md)
 - [Development Guide](DEVELOPMENT.md)
 - [Making Plume available in your language](INTERNATIONALIZATION.md)