TCP Tests

TCP Tests

Overview

TCP tests allow you to monitor whether or not low-level TCP connections can be established on the ports of given hosts, ensuring the availability of several key services such as SSH (22), SMTP (25), DNS (53), VPN over HTTPS (443), and any custom services living on other ports. With built-in response time data, track the performance of your network applications and receive alerts in case of unexpected slowness.

TCP tests can run from both managed and private locations depending on whether you want to launch your TCP connections from outside or inside your network.

Configuration

After choosing to create a TCP test, define your test’s request.

Define request

  1. Specify the Host and the Port to run your test on. By default, the port is set to 443.
  2. Decide whether or not to Track number of network hops (TTL). This option allows you to assert on the number of network hops and to have access to a TCP Traceroute in your test results.
  3. Name your TCP test.
  4. Add env Tags as well as any other tag to your TCP test. You can then use these tags to quickly filter through your Synthetic tests on the Synthetic Monitoring homepage.
  5. Select the Locations to run your TCP test from: TCP tests can run from both managed and private locations depending on whether you want to launch the connection from outside or inside your network.

Click on Test URL to try out the request configuration. You should see a response preview show up on the right side of your screen.

Specify test frequency

TCP tests can run:

  • On a schedule to ensure your most important services are always accessible to your users. Select the frequency you want Datadog to run your TCP test.

Define assertions

Assertions define what an expected test result is. When hitting Test URL basic assertions on response time is added. You must define at least one assertion for your test to monitor.

TypeOperatorValue type
response timeis less thanInteger (ms)

You can create up to 20 assertions per API test by clicking on New Assertion or by clicking directly on the response preview:

Define alert conditions

Set alert conditions to determine the circumstances under which you want a test to fail and trigger an alert.

Alerting rule

When you set the alert conditions to: An alert is triggered if any assertion fails for X minutes from any n of N locations, an alert is triggered only if these two conditions are true:

  • At least one location was in failure (at least one assertion failed) during the last X minutes.
  • At one moment during the last X minutes, at least n locations were in failure.

Fast retry

Your test can trigger retries in case of a failed test result. By default, the retries are performed 300 ms after the first failed test result. The retry interval can be configured with the API.

Location uptime is computed on a per-evaluation basis (whether the last test result before evaluation was up or down). The total uptime is computed based on the configured alert conditions. Notifications sent are based on the total uptime.

Notify your team

A notification is sent by your test based on the alerting conditions previously defined. Use this section to define how and what message to send to your teams.

  1. Similar to monitors, select users and/or services that should receive notifications either by adding a @notificationto the message or by searching for team members and connected integrations with the drop-down box.

  2. Enter the notification message for your test. This field allows standard Markdown formatting and supports the following conditional variables:

    Conditional VariableDescription
    {{#is_alert}}Show when the test alerts.
    {{^is_alert}}Show unless the test alerts.
    {{#is_recovery}}Show when the test recovers from alert.
    {{^is_recovery}}Show unless the test recovers from alert.
  3. Specify how often you want your test to re-send the notification message in case of test failure. To prevent renotification on failing tests, leave the option as Never renotify if the monitor has not been resolved.

Email notifications include the message defined in this section as well as a summary of failed assertions. Notifications example:

Click on Save to save your test and have Datadog start executing it.

Variables

Create local variables

You can create local variables by clicking on Create Local Variable at the top right hand corner of your test configuration form. You can define their values from one of the below available builtins:

{{ numeric(n) }}
Generates a numeric string with n digits.
{{ alphabetic(n) }}
Generates an alphabetic string with n letters.
{{ alphanumeric(n) }}
Generates an alphanumeric string with n characters.
{{ date(n, format) }}
Generates a date in one of our accepted formats with a value of the date the test is initiated + n days.
{{ timestamp(n, unit) }}
Generates a timestamp in one of our accepted units with a value of the timestamp the test is initiated at +/- n chosen unit.

Use variables

You can use the global variables defined in the Settings and the locally defined variables in the URL, Advanced Options, and assertions of your HTTP tests.

To display your list of variables, type {{ in your desired field:

Test failure

A test is considered FAILED if it does not satisfy one or several assertions or if the request prematurely failed. In some cases, the test can indeed fail without being able to test the assertions against the endpoint, these reasons include:

CONNRESET
The connection was abruptly closed by the remote server. Possible causes include the webserver encountering an error or crashing while responding, or loss of connectivity of the webserver.
DNS
DNS entry not found for the test URL. Possible causes include misconfigured test URL or the wrong configuration of your DNS entries.
INVALID_REQUEST
The configuration of the test is invalid (for example, a typo in the URL).
TIMEOUT
The request couldn’t be completed in a reasonable time. Two types of TIMEOUT can happen:
  • TIMEOUT: The request couldn’t be completed in a reasonable time. indicates that the timeout happened at the TCP socket connection level.
  • TIMEOUT: Retrieving the response couldn’t be completed in a reasonable time. indicates that the timeout happened on the overall run (which includes TCP socket connection, data transfer, and assertions).

Permissions

By default, only users with the Datadog Admin and Datadog Standard roles can create, edit, and delete Synthetic TCP tests. To get create, edit, and delete access to Synthetic TCP tests, upgrade your user to one of those two default roles.

If you have access to the custom role feature, add your user to any custom role that includes synthetics_read and synthetics_write permissions.

Further Reading