Choose where new sites go

New hostings land on the server you choose in the Add a website form, or on the one Auto picks. Three settings shape that choice: whether the master takes sites, whether a node is drained, and whether a node is a test node.

Before you start

Sign in as an Owner. Other roles can read Settings but cannot save.
At least one worker is enrolled. Without one, Settings has no Cluster page.
For test nodes, set the preview address template first under Settings, HTTPS & previews, Preview address. A test node builds its site domains from it.

Steps

Let the master host sites, or keep it as control plane only

Open Settings in the sidebar, then Cluster under the Cluster group.
In the New sites group, find Placement. Its badge reads master takes new sites or workers only.
Tick or clear Allow new sites on the master.
Click Save. The page shows “Placement saved — the agent restarts in about 5 s”.

With the box cleared, the master is a control plane only: it runs the panel and manages the workers, and the sites run on the workers. The Add a website form stops offering it and says “This server is set to control-plane only. Sites run on worker servers.” A request that names the master anyway is refused with “Master is in control-plane-only mode (Settings → Cluster → Placement). Pick a worker node from the dropdown.” Sites already on the master stay there.

How Auto picks a server

Auto — pick the best-fit server (recommended) in Which server should host this? scores each candidate and takes the lowest score. A candidate is a worker that is online and not drained, plus the master when it accepts sites. The score weighs the number of sites (45%), the one-minute load average (35%) and the memory in use (20%), each as a share of the highest value among the candidates. A tie goes to the smaller node ID.

If no candidate qualifies, Auto falls back to the master when it accepts sites. Otherwise the form shows “Auto-placement found no online workers and master is in control-plane-only mode. Enrol a worker or enable master hosting in Settings → Cluster → Placement.”

To keep a worker out of Auto for a while, drain it.

Mark a node as a test node

Open Nodes and click the node’s row. For the master, use the row marked this server.
In Placement, click Mark as test and confirm. The button reads Unmark as test afterwards.
The page tells you to restart hyperion-agent on the master so domain validation fully picks up the change. Open Service health, find hyperion-agent and restart it.

The row gets a Test flag. On a test node:

Creating a site asks only for a short name. The preview address template builds the rest of the domain.
The Add a website form refuses a production domain on a test node, and a domain that matches the template on a production node.
Sites already there keep working and show a TEST chip.

Existing hostings do not move when you mark or unmark a node.

Keep search engines away from WordPress test sites

Open Settings, Cluster, then the Test nodes card. It lists the nodes marked as test, or none.
Tick Ask search engines to skip WordPress sites on test nodes and click Save.

Right after a fresh WordPress install on a test node, Hyperion sets blog_public = 0. Change it later in WP admin under Settings, Reading.

Check that it worked

Placement shows the badge you expect, and Which server should host this? lists the master only when it accepts sites.
Test nodes lists the nodes you marked, with · this server for the master.
A drained or offline worker is not picked by Auto. See Drain or rename a node.

If it fails

“The agent’s settings could not be read (…). These are defaults, not what is set, so saving is off until it answers.”: wait for the agent to come back and reload.
A test node is listed as not an enrolled node: the settings name an ID that is not enrolled, for example a removed node. Mark or unmark real nodes on Nodes.
Auto does not choose the node you expected: it picks the lightest candidate, not a fixed one. Pick the server by name in the form.