SLA as a plugin

Let’s create an SLA (success criterion) plugin that checks whether the range of the observed performance measurements does not exceed the allowed maximum value.

Creation

Inherit a class for your plugin from the base SLA class and implement its API (the add_iteration(iteration), the details() method):

from rally.task import sla

@sla.configure(name="max_duration_range")
class MaxDurationRange(sla.SLA):
    """Maximum allowed duration range in seconds."""

    CONFIG_SCHEMA = {
        "type": "number",
        "minimum": 0.0,
    }

    def __init__(self, criterion_value):
        super(MaxDurationRange, self).__init__(criterion_value)
        self._min = 0
        self._max = 0

    def add_iteration(self, iteration):
        # Skipping failed iterations (that raised exceptions)
        if iteration.get("error"):
            return self.success   # This field is defined in base class

        # Updating _min and _max values
        self._max = max(self._max, iteration["duration"])
        self._min = min(self._min, iteration["duration"])

        # Updating successfulness based on new max and min values
        self.success = self._max - self._min <= self.criterion_value
        return self.success

    def details(self):
        return ("%s - Maximum allowed duration range: %.2f%% <= %.2f%%"
                 % (self.status(), self._max - self._min, self.criterion_value))

Usage

The new plugin can be used by specifying it in SLA section. Like below:

{
    "Dummy.dummy": [
        {
            "args": {
                "sleep": 0.01
            },
            "runner": {
                "type": "constant",
                "times": 5,
                "concurrency": 1
            },
            "context": {
                "users": {
                    "tenants": 1,
                    "users_per_tenant": 1
                }
            },
            "sla": {
                "max_duration_range": 2.5
            }
        }
    ]
}