eG Monitoring
 

Measures reported by AWSCloudFrontTest

Amazon CloudFront is a web service that speeds up distribution of your static and dynamic web content, such as .html, .css, .js, and image files, to your users. CloudFront delivers your content through a worldwide network of data centers called edge locations. When a user requests content that you're serving with CloudFront, the user is routed to the edge location that provides the lowest latency (time delay), so that content is delivered with the best possible performance.

In the edge location, CloudFront checks its cache for the requested files. If the files are in the cache, CloudFront returns them to the user. If the files are not in the cache, it does the following:

  1. CloudFront compares the request with the specifications in your distribution. A distribution is where you can specify configuration settings such as:

    • Your origin, which is the Amazon S3 bucket or HTTP server from which CloudFront gets the files that it distributes. You can specify any combination of up to 25 Amazon S3 buckets and/or HTTP servers as your origins.

    • Whether you want the files to be available to everyone or you want to restrict access to selected users.

    • Whether you want CloudFront to require users to use HTTPS to access your content.

    • Whether you want CloudFront to forward cookies and/or query strings to your origin.

    • Whether you want CloudFront to create access logs.

    From the distribution, CloudFront determines the origin server that applies to the requested file type and forwards the request to that server.

  2. The origin servers then send the files back to the CloudFront edge location.

  3. As soon as the first byte arrives from the origin, CloudFront begins to forward the files to the user. CloudFront also adds the files to the cache in the edge location for the next time someone requests those files.

The success of CloudFront relies on the successful delivery of content to users. If errors in request processing go undetected, it can cause content to not be delivered to the intended audience. This is bound to adversely impact user confidence in CloudFront! To avoid this, administrators should be able to promptly detect errors in request processing, rapidly investigate the reason for the errors, and quickly resolve it. This is where the AWSCloudFrontTest test helps.

This test auto-discovers the distributions configured on CloudFront and tracks the requests to and responses of origin servers specified in each distribution. In the process, the test promptly captures HTTP error responses from origin servers, and instantly notifies administrators of the errors. This way, the test pinpoints the distribution that is configured with the origin servers emitting the maximum number of error responses. Administrators can then closely scrutinize such a distribution for any misconfiguration.

Outputs of the test : One set of results for each distribution configured on CloudFront.

First-level descriptor: AWS Region

Second-level descriptor: DistributionID

The measures made by this test are as follows:

Measurement Description Measurement Unit Interpretation
Request Indicates the number of HTTP and HTTPS requests (for all HTTP methods ) to the origin servers specified in this distribution. Number  
Byte_dwnload Indicates the amount of data downloaded by viewers for GET, HEAD, and OPTIONS requests to the origin server specified in this distribution. KB  
Byte_upload Indicates the amount of data uploaded to the origin servers specified in this distribution, using POST and PUT requests. KB  
Total_Error Indicates what percentage of requests to the origin servers in this distribution returned HTTP error response codes such as 4xx or 5xx. Percent Ideally, the value of this measure should be 0. A non-zero value indicates that an HTTP error has occurred.

Compare the value of this measure across distributions to know which distribution is configured with origin servers that have returned the maximum HTTP error responses. You may want to take another look at such distributions to find misconfigurations (if any).
Fourxx_error Indicates what percentage of requests to the origin servers in this distribution returned HTTP error response code 4xx. Percent If the value of the Total_Error measure is abnormally high for a distribution, then you can compare the value of these two measures for that distribution to know what type of HTTP errors were common.

  • HTTP 4xx: This class of status code is intended for situations in which the error seems to have been caused by the client.

  • HTTP 5xx: Response status codes beginning with the digit “5” indicate cases in which the server is aware that it has encountered an error or is otherwise incapable of performing the request.
Fivexx_error Indicates what percentage of requests to the origin servers in this distribution returned HTTP error response code 5xx. Percent