Generator Plugin

The Generator allows testing of synthetic workloads by generating HTTP responses of various sizes. The size and cacheability of the response is specified by the first two components of the requested URL path. This plugin only supports the GET and HEAD HTTP methods.

Path component	Description
1	cache or nocache. If cache is specified, the Generator plugin will respond with Cache-Control headers marking the response as cacheable.
2	Integral number of bytes to return in the response.

Path components after the first 2 are ignored. This means that the trailing path components can be manipulated to create unique URLs following any convenient convention.

The Generator plugin inspects the following HTTP client request headers:

Header	Description
Generator-Delay	The number of milliseconds to wait before sending a response. The default is to not wait.
Generator-MaxAge	The number of seconds that a response should be cached for. This is used in the max-age field of the response’s Cache-Control header.

The Generator plugin publishes the following metrics:

generator.response_bytes:

The total number of bytes emitted

generator.response_count:

The number of HTTP responses generated by the plugin

Examples:

The most common way to use the Generator plugin is to configure it as a remap plugin in remap.config:

map http://workload.example.com/ http://127.0.0.1/ \
  @plugin=generator.so

Notice that although the remap target is never contacted because the Generator plugin intercepts the request and acts as the origin server, it must be syntactically valid and resolvable in DNS.

A 10 byte, cacheable object can then be generated:

$ curl -o /dev/null -x 127.0.0.1:8080 http://workload.example.com/cache/10/caf1fc92332b3a3c8cb8b3826b6a1658

The Generator plugin can return responses as large as you like:

$ curl -o /dev/null -x 127.0.0.1:8080 http://workload.example.com/cache/$((10 * 1024 * 1024))/$RANDOM