HTTP check

Overview

Monitor the up/down status of local or remote HTTP endpoints. The HTTP check can detect bad response codes (e.g. 404), identify soon-to-expire SSL certificates, search responses for specific text, and much more. The check also submits HTTP response times as a metric.

Setup

Installation

The HTTP check is packaged with the Agent, so simply install the Agent on any host from which you want to probe your HTTP sites. Though many metrics-oriented checks are best run on the same host(s) as the monitored service, you may want to run this status-oriented check from hosts that do not run the monitored sites.

If you need the newest version of the HTTP check, install the dd-check-http package; this package’s check will override the one packaged with the Agent. See the integrations-core repository for more details.

Configuration

Create a file http_check.yaml in the Agent’s conf.d directory. See the sample http_check.yaml for all available configuration options:

init_config:

instances:
  - name: Example website
    url: https://example.com/
    # disable_ssl_validation: false      # default is true, so set false to check SSL validation
    # ca_certs: /path/to/ca/file         # e.g. /etc/ssl/certs/ca-certificates.crt
    # check_certificate_expiration: true # default is true
    # days_warning: 28                   # default 14
    # days_critical: 14                  # default 7
    # timeout: 3                         # in seconds. Default is 1.
    skip_event: true # Default is false, i.e. emit events instead of service checks. Recommend to set to true.
  - name: Example website (staging)
    url: http://staging.example.com/
    skip_event: true

The HTTP check has more configuration options than many checks — many more than are shown above. Most options are opt-in, e.g. the Agent will not check SSL validation unless you configure the requisite options. Notably, the Agent will check for soon-to-expire SSL certificates by default.

See the sample http_check.yaml for a full list and description of available options, here is a list of them:

SettingDescription
urlThe URL to test.
timeoutThe time in seconds to allow for a response.
methodThe HTTP method. This setting defaults to GET, though many other HTTP methods are supported, including POST and PUT.
dataThe data option is only available when using the POST method. Data should be included as key-value pairs and will be sent in the body of the request.
content_matchA string or Python regular expression. The HTTP check will search for this value in the response and will report as DOWN if the string or expression is not found.
reverse_content_matchWhen true, reverses the behavior of the content_match option, i.e. the HTTP check will report as DOWN if the string or expression in content_match IS found. (default is false)
username & passwordIf your service uses basic authentication, you can provide the username and password here.
http_response_status_codeA string or Python regular expression for an HTTP status code. This check will report DOWN for any status code that does not match. This defaults to 1xx, 2xx and 3xx HTTP status codes. For example: 401 or 4\d\d.
include_contentWhen set to true, the check will include the first 200 characters of the HTTP response body in notifications. The default value is false.
collect_response_timeBy default, the check will collect the response time (in seconds) as the metric network.http.response_time. To disable, set this value to false.
disable_ssl_validationThis setting will skip SSL certificate validation and is enabled by default. If you require SSL certificate validation, set this to false.
ignore_ssl_warningWhen SSL certificate validation is enabled (see setting above), this setting will allow you to disable security warnings.
ca_certsThis setting will allow you to override the default certificate path as specified in init_config
check_certificate_expirationWhen check_certificate_expiration is enabled, the service check will check the expiration date of the SSL certificate. Note that this will cause the SSL certificate to be validated, regardless of the value of the disable_ssl_validation setting.
days_warning & days_criticalWhen check_certificate_expiration is enabled, these settings will raise a warning or critical alert when the SSL certificate is within the specified number of days from expiration.
headersThis parameter allows you to send additional headers with the request. Please see the example YAML file for additional information and caveats.
skip_eventWhen enabled, the check will not create an event. This is useful to avoid duplicates with a server side service check. This defaults to false.
no_proxyIf set, the check will bypass proxy settings and attempt to reach the check url directly. This defaults to false.
allow_redirectsThis setting allows the service check to follow HTTP redirects and defaults to true.
tagsA list of arbitrary tags that will be associated with the check. For more information about tags, please see our Guide to tagging and blog post, The power of tagged metrics

When you have finished configuring http_check.yaml, restart the Agent to begin sending HTTP service checks and response times to Datadog.

Validation

Run the Agent’s info subcommand and look for http_check under the Checks section:

  Checks
  ======
    [...]

    http_check
    ----------
      - instance #0 [WARNING]
          Warning: Skipping SSL certificate validation for https://example.com based on configuration
      - instance #1 [OK]
      - Collected 2 metrics, 0 events & 4 service checks

    [...]

Compatibility

The http_check check is compatible with all major platforms.

Data Collected

Metrics

network.http.response_time
(gauge)
The response time of an HTTP request to a given url, tagged by url, e.g. 'url:http://example.com'.
shown as second
http.ssl.days_left
(gauge)
Days until SSL certificate expiration
shown as day

Events

Older versions of the HTTP check only emitted events to reflect site status, but now the check supports service checks, too. However, emitting events is still the default behavior. Set skip_event to true for all configured instances to submit service checks instead of events.

The Agent will soon deprecate skip_event, i.e. the HTTP check will only support service checks.

Service Checks

To create alert conditions on these service checks in Datadog, select ‘Network’ on the Create Monitor page, not ‘Integration’.

http.can_connect:

Returns DOWN when any of the following occur:

  • the request to uri times out
  • the response code is 4xx/5xx, or it doesn’t match the pattern provided in the http_response_status_code
  • the response body does not contain the pattern in content_match
  • reverse_content_match is true and the response body does contain the pattern in content_match
  • uri contains https and disable_ssl_validation is false, and the SSL connection cannot be validated

Otherwise, returns UP.

http.ssl_cert:

The check returns:

  • DOWN if the uri’s certificate has already expired
  • CRITICAL if the uri’s certificate expires in less than days_critical days
  • WARNING if the uri’s certificate expires in less than days_warning days

Otherwise, returns UP.

To disable this check, set check_certificate_expiration to false.

Troubleshooting

Need help? Contact Datadog Support.

Further Reading

Learn more about infrastructure monitoring and all our integrations on our blog