This folder contains tools to aid in measuring the scaling capabilities of Kubernetes clusters.
Primarily these tools were designed to measure scaling of large number of pods on a single node, but the code is structured to handle multiple nodes, and may also be useful in that scenario.
The tools tend to take one of two forms:
- Tools to launch jobs and take measurements
- Tools to analyse results
For more details, see individual sub-folders. A brief summary of available tools is below:
| Folder | Description |
|---|---|
| collectd | collectd based statistics/metrics gathering daemonset code |
| lib | General library helper functions for forming and launching workloads, and storing results in a uniform manner to aid later analysis |
| lib/cpu-load* | Helper functions to enable CPU load generation on a cluster whilst under test |
| report | Rmarkdown based report generator, used to produce a PDF comparison report of one or more sets of results |
| scaling | Tests to measure scaling, such as linear or parallel launching of pods |
The tools generate JSON formatted results files via the lib/json.bash functions. The metrics_json_save()
function has the ability to also curl or socat the JSON results to a database defined
by environment variables (see the file source for details). This method has been used to store results in
Elasticsearch and InfluxDB databases for instance, but should be adaptable to use with any REST API that accepts
JSON input.
There are some basic pre-requisites required in order to run the test and process the results:
- A Kubernetes cluster up and running (tested on v1.15.3).
bcandjqpackages.- Docker (only for report generation).
Below are some architecture and internal details of how the code is structured and configured. This will be helpful for improving, modifying or submitting fixes to the code base.
Metrics can be gathered using either a daemonset deployment of privileged pods used to gather statistics
directly from the nodes using a combination of mpstat, free and df, or a daemonset deployment based
around collectd. The general recommendation is to use the collectd based collection if possible, as it
is more efficient, as the system does not have to poll and wait for results, and thus executes the test
cycle faster. The collectd results are collected asyncronously, and the report generator code later
aligns the results with the pod execution in the timeline.
The collected based code can be found in the collectd subdirectory. It uses the collected configuration
found in the collectd.conf file to gather statistics, and store the results on the nodes themselves whilst
tests are running. At the end of the test, the results are copied from the nodes and stored in the results
directory for later processing.
The collectd statistics are only configured and gathered if the environment variable SMF_USE_COLLECTD
is set to non-empty by the test code (that is, it is only enabled upon request).
The privileged statistics pods YAML can be found in the scaling/stats.yaml file.
An example of how to invoke and use this daemonset to extract statistics can be found in the
scaling/k8s_scale.sh file.
The framework includes some tooling to assist in setting up constant pre-defined 'loads' across the cluster to aid evaluation of their impacts on the scaling metrics. See the cpu-load documentation for more information.