# Checks

At its core, argos runs checks and return the results to the service. Here are the implemented checks, with a description of what they do and how to configure them.

## Simple checks

These checks are the most basic ones. They simply check that the response from the service matches what you expect.

| Check | Description | Configuration |
| --- | --- | --- |
| `status-is` | Check that the returned status code matches what you expect. | `status-is: "200"` |
| `status-in` | Check that the returned status code is in the list of codes you expect. | <pre><code>status-in:<br>    - 200<br>    - 302</code></pre> |
| `body-contains` | Check that the returned body contains a given string. | `body-contains: "Hello world"` |
| `headers-contain` | Check that the response contains the expected headers. | <pre><code>headers-contain:<br>    - "content-encoding"<br>    - "content-type"</code></pre> |
| `headers-have` | Check that the response contains the expected headers. | <pre><code>headers-have:<br>    content-encoding: "gzip"<br>    content-type: "text/html"</code></pre> |

```{code-block} yaml
---
caption: argos-config.yaml
---
- domain: "https://example.org"
  paths:
    - path: "/"
      checks:
        - status-is: 200
        - body-contains: "Hello world"
        - headers-contain:
            - "content-encoding"
            - "content-type"
    - path: "/foobar"
      checks:
        - status-in:
            - 200
            - 302
        # It’s VERY important to respect the 4 spaces indentation here!
        - headers-have:
            content-encoding: "gzip"
            content-type: "text/html"
```

## SSL certificate expiration

 Checks that the SSL certificate will not expire soon. You need to define the thresholds in the configuration, and set the `on-check` option to enable the check.


```{code-block} yaml
---
caption: argos-config.yaml
---
ssl:
  thresholds:
    - "1d": critical
    - "5d": warning

- domain: "https://example.org"
  paths:
    - path: "/"
      checks:
        - ssl-certificate-expiration: "on-check"
```