What is hermes?

Hermes is an http/2 traffic generator written in C++ able to send multiplexed requests over one connection at a given rate.

It also measures and calculates some statistics, validates response codes and handles user-defined traffic sequences, a.k.a. scripts.

Because of the nature of the project itself, it has a minimal footprint impact, and has proven to be reliable: traffic is generated in a steady pace, without unwanted traffic bursts. This is achieved by using boost async io_context utility and thread synchronization strategies.

It is based in the nghttp2 implementation, and provides a different functionality than h2load, also written in C++ by the nghttp2 creator, because hermes allows to use traffic scripts, traffic is injected at a pre-defined rate, and validates the results.

Hermes aims to be a low footprint and easy to use but high-performance general use tool.

How can you use it?

Hermes may be used standalone (check the releases!), from a docker container, or as part of a kubernetes deployment.

Executing hermes

You may take a look to Hermes help by just typing ./hermes -h:

hermes: C++ Traffic Generator. Usage:  hermes [options]

options:
       -r <rate>      Requests/second ( Default: 10 )

       -t <time>      Time to run traffic (s) ( Default: 60 )

       -p <period>    Print and save statistics every <period> (s) ( Default: 10 )

       -f <path>      Path with the traffic json definition ( Default: /etc/scripts/traffic.json )

       -s             Show schema for json traffic definition.

       -o <file>      Output file for statistics( Default: hermes.out )

       -h             This help.

At the end of the day a typical use is:

./hermes -r2400 -p1 -t3600

Hermes results, console and file outputs are explained here.

hermes helm chart integration

The idea is simple:

• Add it to your Chart.yaml dependencies.
• Reference hermes in your chart under .Values.hermes.image repository and tag.
• Define a config map for your traffic definition (script) and reference it in your values with the name you gave it under .Values.hermes.script.cm

But what is inside that ConfigMap? Your traffic script definition.

And that's it!

If you have some doubts, take a look at the example-hermes helm chart, or the following examples.

Examples

This repository provides a server-mock implementation which enables you to test and taste easily how hermes works.

Container to Container example

1. Build and run a server-mock container by following these instructions.
2. Attach to a docker container running a ghcr.io/jgomezselles/hermes image, and create a script file like the one located in the helm example.
3. Run hermes providing the path to your new script:

./hermes -r2400 -p1 -t3600 -f <path/to/script.json>

hermes in kubernetes example

1. Build (but not run) a server-mock by following these instructions.
2. Update the example-hermes helm chart dependencies, and install the chart:

helm dep update helm/example-hermes
helm install example-hermes helm/example-hermes

3. Run hermes

kubectl exec <hermes-pod> -c hermes -- /hermes/hermes -p1 -t10 -r1000

The server-mock prints every received request to the console, so you can check the received requests by inspecting the logs: kubectl logs <server-mock-pod>

Developing & testing hermes

Take a look to hermes dev info here.

License

The Software implemented in this repository is distributed under MIT license, as stated in the LICENSE file. It makes use of some boost C++ library functionalities, which have their own license. Hermes core functionality is based on nghttp2, and json handling is done with rapidjson, both under MIT license. Tests are done with Googletest, which is published under BSD 3-Clause License.