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Performance Testing Framework

The Kong Gateway codebase includes a performance testing framework. It allows Kong developers and users to evaluate the performance of Kong itself as well as bundled or custom plugins, and plot frame graphs to debug performance bottlenecks. The framework collects RPS (request per second) and latencies of Kong processing the request to represent performance metrics under different workloads.

The framework is implemented as an extension to Kong’s integration test suite.

Installation

The framework uses busted and some Lua development dependencies of Kong. To set up the environment, run make dev on your Kong repository to install all Lua dependencies.

Drivers

Three “drivers” are implemented depending on different environments, accuracy requirements, and setup complexity.

Driver	Test between git commits	Test between binary releases	Flamegraph	Test unreleased version
local	yes		yes	yes
docker	yes	yes
terraform	yes	yes	yes

local Driver reuses users’ local environment. It’s faster to run, but the RPS and latency number may be influenced by other local programs and thus inaccurate.
- Requires Lua development dependencies of Kong, OpenResty, and wrk be installed.
- Requires SystemTap, kernel headers, and build chain to be installed if generating FlameGraph.
docker Driver is solely based on Docker images. It’s the most convenient driver to setup as it requires less dependencies. But it may also be influenced by other local programs and Docker network performance. And it doesn’t support FlameGraph generation.
terraform Driver runs in remote VM or bare metal machine. It’s most accurate, but it requires Terraform knowledge to operate and setup.
- Requires the Terraform binary be installed.
- Requires git binary if testing between git commits. When testing between git commits, the framework assumes the current directory is Kong’s repo. It will stash your working directory and unstash after test is finished. When using the docker or terraform driver, the framework derives the base version of each commit and uses the matching Docker image or Kong binary package and puts local source code inside.

Workflow

Like Kong’s integration tests, the performance test is written in Lua. Several test cases can share the same Lua file.

The following code snippet demonstrates a basic workflow for defining a workload and load testing Kong.

local perf = require("spec.helpers.perf")

perf.use_driver("docker")

local versions = { "git:master", "2.4.0" }

for _, version in ipairs(versions) do
  describe("perf test for Kong " .. version .. " #simple #no_plugins", function()
    local bp
    lazy_setup(function()
      local helpers = perf.setup()

      bp = helpers.get_db_utils("postgres", {
        "routes",
        "services",
      })

      local upstream_uri = perf.start_upstream([[
      location = /test {
        return 200;
      }
      ]])

      local service = bp.services:insert {
        url = upstream_uri .. "/test",
      }

      bp.routes:insert {
        paths = { "/s1-r1" },
        service = service,
        strip_path = true,
      }
    end)

    before_each(function()
      perf.start_kong(version, {
        --kong configs
      })
    end)

    after_each(function()
      perf.stop_kong()
    end)

    lazy_teardown(function()
      perf.teardown()
    end)

    it("#single_route", function()
      local results = {}
      for i=1,3 do
        perf.start_load({
          path = "/s1-r1",
          connections = 1000,
          threads = 5,
          duration = 10,
        })

        ngx.sleep(10)

        local result = assert(perf.wait_result())

        print(("### Result for Kong %s (run %d):\n%s"):format(version, i, result))
        results[i] = result
      end

      print(("### Combined result for Kong %s:\n%s"):format(version, assert(perf.combine_results(results))))

      perf.save_error_log("output/" .. version:gsub("[:/]", "#") .. "-single_route.log")
    end)
  end)
end

The test can be run as a normal busted-based test. Run it with bin/busted path/to/this_file_spec.lua.

More examples can be found in the spec/04-perf folder in the Kong repository.

Sample Output

### Result for Kong git:96326b894f712b5d03bb1bf7ac02d531f6128cd1 (run 1):
Running 10s test @ http://10.88.145.9:8000/s1-r1
  5 threads and 1000 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    17.51ms   61.46ms   1.04s    98.99%
    Req/Sec    14.31k     2.61k   20.80k    82.59%
  672831 requests in 10.07s, 154.07MB read
  Socket errors: connect 0, read 0, write 0, timeout 246
Requests/sec:  66803.45
Transfer/sec:     15.30MB
### Result for Kong git:96326b894f712b5d03bb1bf7ac02d531f6128cd1 (run 2):
Running 10s test @ http://10.88.145.9:8000/s1-r1
  5 threads and 1000 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    14.71ms   10.66ms  96.77ms   66.18%
    Req/Sec    14.45k     1.79k   20.19k    70.80%
  718942 requests in 10.08s, 164.70MB read
Requests/sec:  71337.25
Transfer/sec:     16.34MB
### Result for Kong git:96326b894f712b5d03bb1bf7ac02d531f6128cd1 (run 3):
Running 10s test @ http://10.88.145.9:8000/s1-r1
  5 threads and 1000 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    14.47ms   10.13ms  82.81ms   66.57%
    Req/Sec    14.60k     1.64k   22.98k    72.00%
  726452 requests in 10.07s, 166.42MB read
Requests/sec:  72141.41
Transfer/sec:     16.53MB
### Combined result for Kong git:96326b894f712b5d03bb1bf7ac02d531f6128cd1:
RPS     Avg: 70094.04
Latency Avg: 15.52ms    Max: 1040.00ms

With samples in spec/04-perf, the RPS and latency results, Kong error logs and FlameGraph files are saved to output directory under current directory.

API

`perf.use_driver`

syntax: perf.use_driver(name, options?)

Uses driver name, which must be one of “local”, “docker” or “terraform”. Additional parameters for the driver can be specified in options as a Lua table. Throws error if any.

Only the terraform driver expects an options parameter, which contains following keys:

provider The service provider name, right now only “equinix-metal”.
tfvars Terraform variables as a Lua table; for equinix-metal provider, packet_project_id and packet_auth_token is required.

`perf.set_log_level`

syntax: perf.set_log_level(level)

Sets the log level; expect one of "debug", "info", "notice", "warn", "error" and "crit". The default log level is "info".

`perf.set_retry_count`

syntax: perf.set_retry_count(count)

Sets retry time for each “driver” operation. By default every operation is retried 3 times.

`perf.setup`

syntax: helpers = perf.setup()

Prepares environment and returns the spec.helpers module. Throws error if any.

The framework sets up some environment variables before importing spec.helpers modules. The returned helper is just a normal spec.helpers module. Users can use the same pattern in integration tests to setup entities in Kong. DB-less mode is currently not implemented.

`perf.start_upstream`

Syntax:

upstream_uri = perf.start_upstream(nginx_conf_blob)

Starts upstream (Nginx/OpenResty) with given nginx_conf_blob. Returns the upstream URI accessible from Kong’s view. Throws error if any.

`perf.start_kong`

Syntax:

perf.start_kong(version, kong_configs?)

Starts Kong with given version and Kong configurations in kong_configs as a Lua table. Throws error if any.

To select a git hash or tag, use "git:<hash>" as version. Otherwise, the framework will treat the version as a release version and will download binary packages from Kong’s distribution website.

`perf.stop_kong`

Syntax:

perf.stop_kong()

Stops Kong. Throws error if any.

`perf.teardown`

Syntax:

perf.teardown(full?)

Teardown. Throws error if any. With the terraform driver, setting full to true terminates all infrastructure, while by default it does cleanup only to speed up successive runs.

`perf.start_stapxx`

Syntax:

perf.start_stapxx(stapxx_file_name, arg?)

Starts the Stap++ script with stapxx_file_name exists in available stapxx scripts and additional CLI args. Throws error if any.

This function blocks test execution until the SystemTap module is fully prepared and inserted into the kernel. It should be called before perf.start_load.

`perf.start_load`

Syntax:

perf.start_load(options?)

Starts to send load to Kong using wrk. Throws error if any. Options is a Lua table that may contain the following:

path String request path; defaults to / .
uri Base URI exception path; defaults to http://kong-ip:kong-port/.
connections Connection count; defaults to 1000.
threads Request thread count; defaults to 5.
duration Number of performance tests duration in seconds; defaults to 10.
script Content of wrk script as string; defaults to nil.

`perf.wait_result`

Syntax:

result = perf.start_load(options?)

Waits for the load test to finish and returns the result as a string. Throws error if any.

Currently, this function waits indefinitely, or until both wrk and Stap++ processes exit.

`perf.combine_results`

Syntax:

combined_result = perf.combine_results(results, …)

Calculates multiple results returned by perf.wait_result and returns their average and min/max. Throws error if any.

`perf.generate_flamegraph`

Syntax:

perf.generate_flamegraph(path, title?)

Generates a FlameGraph with title and saves to path. Throws error if any.

`perf.save_error_log`

Syntax:

perf.save_error_log(path)

Saves Kong error log to path. Throws error if any.

Customization

Add new test suite

All tests are stored in spec/04-perf/01-rps and spec/04-perf/02-flamegraph of the Kong repository. Add a new file under one of the directories and put #tags in the test description.

Add new provider in terraform

Users can use the terraform driver in most major service providers as long as it’s supported by Terraform. The following contracts are made between the framework and terraform module:

The terraform files are stored in spec/fixtures/perf/terraform/<provider>.

Two instances are provisioned, one for running Kong and another for running an upstream and load (worker). A firewall allows bidirectional traffic between the two instances and from the public internet. Both instances run Ubuntu 20.04/focal.

An SSH key to login into both instances exists or will be created in spec/fixtures/perf/terraform/<provider>/id_rsa. The logged-in user has root privilege.

The following are terraform output variables:

kong-ip Kong node public IP.
kong-internal-ip Kong node internal IP (if unavailable, provide kong-ip).
worker-ip Worker node public IP.
worker-internal-ip Worker node internal IP (if unavailable, provide worker-ip).