Introduction

This action leverages steadybit/failure-azure-functions-net and the Azure App Configuration to fill the tmp disk of an Azure Function application.

Use Cases

• Understand how an Azure Function application behaves when it pollutes the tmp directory.

Prerequisites

Azure Function must be using v4 isolated worker model and .NET 8 or higher.

Azure Function must be wrapped with the Steadybit Injection Middleware.

Azure Function application must have STEADYBIT_FAILURE_INJECTION_ENDPOINT environment variable set to the Azure App Configuration endpoint.

Please note that multiple parallel failure injections on the same Azure Function are not supported.

Important Considerations

The default implementation of the Azure App Configuration middleware in .NET is non-blocking. Therefore, the configuration refresh does not occur in the request where refresh started; instead, it is active from that request onward. In Azure Functions, this might present itself as flaky due to how the Azure Function Consumption Plan operates, which reuses instances with the previous state (you need one request beforehand to get the latest configuration).

Parameters

Parameter	Description	Default
Duration	The duration of the attack.	30s
Rate	The rate of invocations to affect. (100 = all request, 50 = half of all requests)	100%
Megabytes	Size in MB of the file created in tmp.