# assert

stop a host when a check command fails

The plan marks the step with \* and runs nothing. Apply runs the command. A failed assert stays pending on the host, and the next apply runs it again, also when nothing else changes.

## Keys

| Key | Type | Default | Meaning |
| --- | --- | --- | --- |
| [`command`](#assert.command) | string | required | check command |
| [`message`](#assert.message) | string | required | error when the check fails |

### `assert.command` {#assert.command}

string, required

Check command. It runs during apply, through sh -e as root, in /. Exit 0 passes.

### `assert.message` {#assert.message}

string, required

Error when the check fails. The host fails with it when the command exits non-zero, followed by the shell's error when the exit is 126 or 127.

## Example

```yaml
- name: Check that nginx answers
  assert:
    command: curl -fsS http://localhost/
    message: nginx does not answer on port 80
```