`metrics/collect`¶

The metrics/collect task enables collection of built-in metrics. It generates a stream of HTTP requests to one or more app versions, with payload (optional), and collects latency and error metrics.

Example¶

The following start action contains a metrics/collect task which is executed at the start of the experiment. The task sends a certain number of HTTP requests to each version specified in the task, and collects built-in latency/error metrics for them.

start:
- task: metrics/collect
  with:
    versions:
    - name: iter8-app
      url: http://iter8-app.default.svc:8000
    - name: iter8-app-candidate
      url: http://iter8-app-candidate.default.svc:8000

Inputs¶

Field name	Field type	Description	Required
numQueries	int	number of requests to be sent to each version. Default value is 100.	No
time	string	Duration of the `metrics/collect` task run. Specified in the Go duration string format (example, `5s`). If both `time` and `numQueries` are specified, then `time` is ignored.	No
qps	float	Number of queries per second sent to each version. Default is 8.0. Setting this to 0 will maximizes query load without any wait time between queries.	No
connections	int	Number of parallel connection used for sending queries. Default is 4.	No
loadOnly	bool	If set to true, this task will send requests without collecting metrics. Default value is `false`.	No
payloadStr	string	String data to be sent as payload. If this field is specified, Iter8 will send HTTP POST requests to versions using data as the payload.	No
payloadURL	string	URL of payload. If this field is specified, Iter8 will send HTTP POST requests to versions using data downloaded from this URL as the payload. If both `payloadStr` and `payloadURL` is specified, the former is ignored.	No
contentType	string	Content type HTTP header value. This is intended to be used in conjunction with one of the `payload*` fields above. If this field is specified, Iter8 will send HTTP POST requests to versions using this content type header value.
versions	[]Version	A non-empty list of versions.	Yes

Version¶

Field name	Field type	Description	Required
name	string	Name of the version. Version names must be unique. If the version name matches the name of a version in the experiment's `versionInfo` section, then the version is considered real. If the version name does not match the name of a version in the experiment's `versionInfo` section, then the version is considered pseudo. Built-in metrics collected for real versions can be used within the experiment's `criteria` section. Pseudo versions are useful if the intent is only to generate load (`GET` and `POST` requests). Built-in metrics collected for pseudo versions cannot be used with the experiment's `criteria` section.	Yes
headers	map[string]string	Additional HTTP headers to be used in requests sent to this version.	No
url	string	HTTP URL of this version.	Yes

Result¶

This task will run for the specified duration (time), send requests to each version (versions) at the specified rate (qps), and will collect built-in metrics for each version. Built-in metric values are stored in the metrics field of the experiment status in the same manner as custom metric values.

The task may result in an error, for instance, if one or more required fields are missing or if URLs are mis-specified. In this case, the experiment to which it belongs will fail.

Start vs loop actions¶

If this task is embedded in start actions, it will run once at the beginning of the experiment.

If this task is embedded in loop actions, it will run in each loop of the experiment. The results from each run will be aggregated.

Load generation without metrics collection¶

You can use this task to send HTTP GET and POST requests to app versions without collecting metrics by setting the loadOnly input to true.

metrics/collect¶