Cloud LOad StressEr is a collection of tools for generating network traffic and collecting metrics from a network service that is the target for the load testing. The package includes several utilities for testing different kind of network protocols and a top-level manager for them. The utilities are called workers. The manager (or the controller) consists of a daemon providing JSON REST API, and a Web application communicating with the daemon and implementing a user interface.

The workers configuration is communicated via Redis, where the currently running configuration is stored. It provides the mechanism for changing worker parameters without restarting a worker, by pushing a new configuration to the Redis instance. The controller displays the current configuration and allows to update it and re-configure workers on the fly.

The statistics from the workers are collected into InfluxDB, and the controller implements generating basic statistics plots.

In order to perform a load testing it is necessary to have a Docker infrastructure that would allow creating a sufficient number of workers. For testing purposes, one Docker host is enough. As already mentioned, it is required to have Redis and InfluxDB instances.

The package installation requires Go utilities. To build and install the whole package into $GOPATH/bin

go get github.com/qmsk/close

Another way is to clone the repository and use a provided Makefile that will build the utilities locally, without installing them.

Workers and the controller can be installed separately:

go get github.com/qmsk/workers
go get github.com/qmsk/control-web

The web controller is a Javascript application and it requires its JS assets/dependencies installed via Node.js package manager.

git clone github.com/qmsk/close
cd close/control-web/static
npm install

There is a Docker build file provided as well, so

make
docker build .

will produce a Docker image with all the binaries installed. docker-build is an example of necessary steps to build a Docker image if the underlying Docker infrastructure is based on Docker Swarm.

Workers are run as Docker containers, and perform the actual measurement / load-generation work. Currently, there are three types of workers implemented:

• ICMP Ping
• DNS Ping
• UDP Sender

ICMP Ping worker sends ICMP packets over IPv4 or IPv6 at a configurable interval towards a specified target. It measures RTT delay as its only metric.

DNS Ping worker measures a delay to perform a DNS resolution. It generates DNS queries and reports the time to get a response. DNS timeout, DNS server, the interval between queries, their type and target are the worker configurable options.

UDP Sender generates a continuous flow of UDP packets with configurable rate, payload size and the total number of packets to send. It allows specifying the source IP address and port. It reports the following counters: the number of packets sent, the number of bytes sent, the number of sending errors, the number of rate underruns. An underrun might happen if the configured rate is higher than what can be achieved with available resources.

In order to collect more statistics from UDP load testing the UDP receiver utility can be used as a target for the UDP Sender. It collects a number of measurements that represent both the network conditions and the target service performance under UDP load. For more details see RecvStats struct.

Sometimes it is necessary to provide a networking environment for running workers, for example to setup OpenVPN certificates, gateways etc. This functionality is provided by clients. A client is a docker container that does not generate any network load, thus it does not produce any metrics. It can store necessary configuration files for the workers that can bind to its networking environments, potentially sharing the networking configuration between one set of workers and having different settings for another set. I.e. workers with VPN enabled and without it.

The workers and clients configuration is stored in a TOML formatted file. Sections [workers.name] describe a worker configuration, whereas [clients.name] contain clients settings.

The clients and workers configurations both contain the following fields.

• Count - the number of containers to run
• Image - the Docker image to create containers from
• Privileged - whether to run the container in a privileged mode

Disk volumes can be attached to the clients and are configured via Volume, VolumePath, VolumeFmtID, VolumeReadonly - see corresponding Docker volumes documentation.

The workers configuration allows setting up the client that the worker "attaches" to. It is necessary to specify the worker's Type ("icmp_ping", "udp_send", "dns").

When first executed the configuration is stored into Redis. The workers subscribe to configuration updates from Redis. The controller shows the running configuration and pushes configuration updates to workers.

Workers report statistics to InfluxDB. There are two types of statitics: latency statistics include time measurements (for example, the round trip time of an ICMP packet, or a DNS resolution time), rate statistics are counters per time unit (for example, the number of packets per second). To configure a worker that supports a certain set of statistics it is necessary to provide Stats configuration field that contains the InfluxDB URL path and query parts. Each worker instance is assigned an identifier and it can be given in the URL with the $id variable. Each particular statistics should be assigned to an InfluxDB URL as well via LatencyStats and RateStats configuration fields.

The controller reports the statistics from InfluxDB.

This work was supported by the Academy of Finland project "Cloud Security Services" (CloSe) at Aalto University Department of Communications and Networking.