# Set up environments > An environment is a set of variables — base URL, tokens, headers — that you switch in one go. Define one for local, staging and production, and swap between them without touching a single request. ## Create an environment 1. Press ⌘⇧E to open **Manage Environments**, or pick it from the **● ENV** pill at the right end of the toolbar. 2. Click **New environment**. It appears in the list already in rename mode; type a name — `Staging`, `Production` — and press ↩. The coloured dot next to it is derived from the name, so the same name always gets the same colour. 3. Add variables on the right: a **KEY**, a **VALUE**, and whether the row is **Enabled** and **Secret**. `BASE_URL` and `API_KEY` are the usual first two. You can also start from the command palette: ⌘K, then *New Environment…*. Environments belong to the workspace you are in. The first workspace ships with one called **Default**, which already holds the `baseUrl` used by the sample requests. ## Use variables in a request Wrap the name in double braces anywhere a value goes: URL, query parameters, headers, body, auth fields. Mariner resolves it against the active environment when you send.

POST URL bar

```text {{BASE_URL}}/launch/v1/manifests?key={{API_KEY}} ``` With **Staging** active, `{{BASE_URL}}` resolves to `https://staging.acme-labs.dev`. Switch to **Production** and the same requests point at the real server. Under the URL field a preview row shows the exact URL that will go on the wire, with secrets masked; the copy button next to it copies the real thing. In the field itself, a token's **colour tells you its state** and the `{{ }}` / `:` syntax tells you its family — so the two ways of being broken look the same on both: - **Violet** {{token}} — resolved through the environment cascade. - **Blue** :slug — a path variable of this request, filled in. - **Amber** {{token}} · :slug — declared, but its value is empty. It substitutes to nothing, which silently drops a path segment. - **Red** {{token}} · :slug — not declared anywhere. It goes on the wire literally. Hovering a token shows its value and which layer it came from.

A request whose URL is {{baseUrl}}/status/:code: the environment variable in violet, the path variable in blue, and the resolved URL https://httpbin.org/status/200 right under the field — VARIABLES · {{baseUrl}} from the environment, :code from Params — resolved right under the field

## Switch environments Three ways, fastest first: - ⌘E opens the picker from anywhere — arrow to an environment, press ↩. - ⌘K and type the environment's name: *Switch Environment › Production*. - Click the **● ENV** pill in the toolbar. Choosing **No Environment** leaves only request-local variables in play. When you switch workspace, Mariner keeps the environment with the same name active if the new workspace has one. ## Manage variables Right-click a variable in the manager for **Duplicate**, **Copy to Environment ▸**, **Move to Environment ▸** and **Delete**. Copying or moving to another environment replaces a variable with the same key there — handy for promoting a value from Staging to Production. Right-click an environment for **Rename**, **Duplicate** (variables included) and **Delete**.

Mariner refuses to send a request that still contains an unresolved {{token}} or :slug, and tells you which ones. You do not have to send to find out: the {} chip under the URL field carries the token count, and turns amber with a ⚠ and the number of variables that contribute nothing. Open it and every broken token has a **Define** beside it. For a {{token}} that opens the environment manager already on that variable's row — creating the row when the variable does not exist yet, in the environment the cascade named — with the caret in VALUE. For a :slug it opens the Path Variables section of the Params tab. The response pane offers the same fix after a blocked send.

--- Source: https://marinerhttp.dev/docs/environments · Mariner docs