HTTP default checks and policies

  • Release version: Yokohama
  • Updated January 30, 2025
  • 2 minutes to read
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    Summary of HTTP default checks and policies

    Agent Client Collector offers built-in HTTP health monitoring policies, designed to help ServiceNow customers monitor and verify the availability and performance of HTTP endpoints. These policies include specific checks that validate HTTP redirection behavior, response times, and endpoint metrics to ensure your services are operating as expected.

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    Key Features

    • HTTP Entry Point Events Policy: Includes checks such as:
      • util.check-http-follow-redirect: Confirms that HTTP redirects can be followed for a configurable number of requests. It supports authentication options and AWS S3 integration for dynamic configuration.
      • util.check-http-response: Measures URL response times and triggers events with CRITICAL or WARNING severity based on user-defined thresholds, enabling proactive incident detection.
    • HTTP Entry Point Metrics Policy: Includes the util.metrics-http-curl check, which collects detailed HTTP timing metrics using curl. This requires a proxy agent and supports customization of curl arguments and metric naming schemes.

    Practical Use and Benefits

    • These checks enable automated monitoring of HTTP endpoints directly within your ServiceNow environment, providing timely alerts on performance degradation or failures.
    • AWS S3 integration allows centralized and dynamic configuration management for checks executed in different environments.
    • Customizable parameters such as redirect limits, timeout thresholds, and curl arguments give you flexibility to tailor monitoring to your specific HTTP services.
    • Output events and metrics provide actionable data to support troubleshooting and maintain service availability.

    Expected Outcomes

    • Reliable verification of HTTP endpoint health, including redirect handling and response time measurements.
    • Generation of detailed performance metrics to assist in capacity planning and performance tuning.
    • Integration of monitoring data into ServiceNow’s CMDB through the Monitoring HTTP Entrypoint, facilitating centralized endpoint management.

    Agent Client Collector provides the following policies for HTTP health monitoring. Policies come with the checks specified in the tables below.

    Table 1. HTTP entry point events policy
    Type Check Description Usage and Usage Example Output
    Event util.check-http-follow-redirect Verifies that redirection links can be followed in a set number of requests.
    Usage check-head-redirect.rb (options):
    • -A, --auth-first-only: Use basic auth on first request only.
    • -aws-access-key-id: AWS Access Key. Either set ENV["AWS_ACCESS_KEY_ID"] or provide it as an option on agent.
    • -r -aws-region: AWS Region (defaults to us-east-1).
    • --aws-secret-access-key: AWS Secret Access Key. Either set ENV["AWS_SECRET_ACCESS_KEY"] or provide it as an option on agent.
    • -R --redirect: Follow first <N> redirects
    • -g --get-redirects: Follow first <N> redirects with GET requests.
    • -s, --s3-config-bucket: S3 config bucket to get configuration.
    • -k, --s3-config-key: S3 config key to get configuration.
    • -u, --url: URL needs to be updated in Monitoring HTTP Entrypoint/cmdb_ci_endpoint_http_list.do for the CI.
    The Aws-region, aws-secret-key, aws-access-key ,s3-config, s3-config-key parameters are useful if you do not want to configure connection information in other check parameters. If a bucket and key have access to the environment in which the Sensu check executes in, provide an AWS key and token and the checks pull the specified JSON file from S3 and merge the JSON config into the current check configuration.

    Usage example: command: check-head-redirect.rb -R 10 -u 'https://servicenow.com'

    		 Check Head Redirect OK
    Event util.check-http-response Verifies URL response time and raises a CRITICAL/WARNING event if elapsed time exceeds provided CRITICAL/WARNING thresholds. Otherwise, it raises an OK event.

    Usage: check-head-redirect.rb (options)

    • -R, --redirect: Follow first <N> redirects.
    • -w --timeout_warning: Set the timeout threshold for warning in milliseconds.
    • -c --timeout_critical: Set the timeout threshold for critical in milliseconds.
    • -u, --url URL needs to be updated in Monitoring HTTP Entrypoint/cmdb_ci_endpoint_http_list.do for the CI.

    Usage example: command: check-head-redirect.rb -R 10 -u 'https://servicenow.com' -w 3000 -c 5000

    		 Check Head Redirect OK
    Table 2. HTTP entry point metrics policy
    Type Check Description Usage and Usage Example Output
    Metric util.metrics-http-curl Retrieves metrics on HTTP endpoints using curl.

    This check requires a proxy agent.
    Usage:
    • -a, --curl_args "CURL ARGS": Additional arguments to pass to curl.
    • s, --scheme SCHEME: Metric naming scheme, text to append to metric (Default: hostname).
    • -u, --url: URL needs to be updated in Monitoring HTTP Entrypoint/cmdb_ci_endpoint_http_list.do for the CI.

    Usage example: metrics-curl.rb -u myURL.com -a -Lk

    		 Check run successfully. Output:

    ws10.curl_timings.time_total 0.219622 1642749209

    ws10.curl_timings.time_namelookup 0.145494 1642749209

    ws10.curl_timings.time_connect 0.151103 1642749209

    ws10.curl_timings.time_pretransfer 0.168569 1642749209

    ws10.curl_timings.time_redirect 0.095899 1642749209

    ws10.curl_timings.time_starttransfer 0.219351 1642749209

    ws10.curl_timings.http_code 200 1642749209