Real User Network Error Logging

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Catchpoint RUM can detect when end users are unable to access applications due to various problems such as DNS failures, connection timeouts/resets, page abandonment, and HTTP errors. Network Error Logging in RUM provides a great complement to node-based tests where the same errors can be detected proactively from predetermined vantage points. Network Error Logging (NEL) defines a response header declaring a reporting policy. The user agent leverages the header and policy to report network errors back to Catchpoint.

Configuration

To start using NEL, configure your application to respond with the following HTTP headers: 
Report-To: {"group":"network-errors","max_age":2592000,"endpoints":\[{"url":"https://r.3gl.net/hawklogserver/**\<app id\>**/re.p"}\]}

NEL: {"report_to":"network-errors","max_age":2592000,"success_fraction":0,"failure_fraction":1.0, "include_subdomains": true}

  • Policy setting only works for webpages that use HTTPS.
  • Reporting endpoint must also be HTTPS, otherwise, browser throws it out.
  • Abandoned requests can be caused by rendering engine logic that precaches and preloads URLs.

The app id should be replaced with your RUM app's id from the Catchpoint portal. This can be found in the properties page for the RUM app you wish to capture errors for.

Note: The Restrict NEL Collection option in App Details should be disabled to collect NEL data.

Analysis

Once this data is captured, it can be viewed in Explorer as well as the RUM Smartboard.

Configure NEL in Fastly

To configure NEL for Fastly, please follow the steps below:

  1. Log in to your fastly.
  2. Click Configure in the main menu.
  3. Select your service from the Service pulldown.
  4. Click on the blue Configuration menu on the top right and select  "Clone Active"
  5. Click Content
  6. Click Creater Header
    .
  7. Enter the values as shown in the screenshot.
    • Make sure that json string has quotes escaped with %22
    • Make sure the json ins enclosed n quotes ("")
    • Example: "{%22report_to%22:%22network-errors%22,%22max_age%22:2592000,%22success_fraction%22:0,%22failure_fraction%22:1.0,%22include_subdomains%22: true}"
  8. Click Save
  9. Do the same for each header
  10. Click Activate