HTTP Flooder

Hello! This project contains:

1. A CLI to flood HTTP servers with requests (in the flooder directory).
2. A dummy api (in the dummy-api directory).

Table of Contents:

• Flooder - documentation for the flooder CLI.
• Dummy API - documentation for the dummy API.
• Docker - examples showcasing the interaction between the two via Docker.

Both applications are written in Go, so you'll need to have it installed to be able to compile the programs. They only use the standard library, so don't worry - mucking around with the GOPATH or using Go modules isn't necessary.

You can also skip to the Docker section to just build the applications with that.

Flooder

How does it work?

The flooder initiates concurrent HTTP requests against a specified server endpoint. We can customize the way it works through the following flags:

flag	type	description	default
duration	int	how long would we like to run the test for (in seconds)?	10
endpoint	string	the endpoint to GET, e.g. http://cool-api:8080/wow
maxRetry	int	max retries to make for failed requests (not implemented)	3
report	string	output the report to a JSON file	""
requestsPerSecond	int	number of GET requests per second to initiate against the endpoint	1
timeout	int	timeout in milliseconds for the request to finish before failing	1000
verbose	bool	verbose logging while querying the servers	false

After a run, the tool will output a summary about how well the server performed against our flood of requests.

Let's see

❯ make flooder

❯ ./bin/flooder -endpoint http://google.com -requestsPerSecond 3 -duration 4 -report report.json
Starting flood. :-)
Running for 4 second(s), initiating 3 request(s) per second. Total requests send to server will be 12.
Sending batch 1
Sending batch 2
Sending batch 3
Sending batch 4

Total Requests: 12
     Successes: 12
      Failures: 0
  Success Rate: 100.00000%
  Failure Rate: 0.00000%
  Average TTFB: 130.582007ms
  Average TTLB: 131.13785ms
         Delta: 555.843µs

❯ jq . report.json
{
  "successes": 12,
  "failures": 0,
  "ttfb": 130582007,
  "ttlb": 131137850
}

The definitions for TTFB and TTLB that we're using are as follows:

Time to first byte - the duration between the time when we initiate a connection to the server and the time when we receive the first byte of the server's response headers.

Time to last byte - the duration between the time when we initiate a connection to the server and the time when we finish reading the server's response body.

Dummy API

How does it work?

A dummy API is exactly what it sounds like. It'll spin up a web server serving one endpoint /time that will output time information about whatever timezone we pass it via the tz query parameter (UTC by default). See examples below.

In addition, we can customize how reliable our web server behaves through the following flags, namely delayInterval and failureRate.

flag	type	description	default
bind	string	the bind address and port for the server to listen on	":8080"
delayInterval	string	add a random delay in milliseconds before processing a request	"0,100"
failureRate	float	percentage of requests to respond with 500s to, e.g. 0.13 for 13%	0.1

Let's see

❯ make dummy-api

❯ ./bin/dummy-api -failureRate 0 &

❯ curl -sG http://localhost:8080/time -d tz=America/New_York | jq -r '"\(.zone) \(.unix)"'
EDT 1588641463

❯ curl -sG http://localhost:8080/time -d tz=Europe/Vilnius | jq -r '"\(.zone) \(.unix)"'
EEST 1588641513

❯ curl -sG http://localhost:8080/time -d tz=Chile/EasterIsland | jq .
{
  "now": "2020-05-04T19:22:29.6771843-06:00",
  "zone": "-06",
  "offset": -21600,
  "utc": "2020-05-05T01:22:29.6771843Z",
  "unix": 1588641749,
  "unixNano": 1588641749677184300
}

❯ kill -TERM $!

For more documentation about valid values for tz, please see the godoc for the api package.

Docker

The following is a manual walkthrough of the contents of ./test.sh as it's essentially a full integration test.

Build our images:

❯ make images

Create a Docker network for both our applications:

❯ docker network create wow

Start up the dummy API, serving responses randomly with a rather large failure rate of 27%, and a delay interval of anywhere from 0 to 50 milliseconds:

❯ docker run --rm --detach --network=wow --name=api dummy-api -failureRate 0.27 -delayInterval 0,50

Once we're done testing, don't forget to stop this container via docker stop api. For now, let's continue and run the flooder against our API for 100 seconds at 100 requests per second:

❯ docker run --rm --network=wow flooder -endpoint http://api:8080/time -duration 100 -requestsPerSecond 100 2>/dev/null
Starting flood. :-)
Running for 100 second(s), initiating 100 request(s) per second. Total requests
send to server will be 10000.
Sending batch 1
Sending batch 2
...
Sending batch 99
Sending batch 100

Total Requests: 10000
     Successes: 7311
      Failures: 2689
  Success Rate: 73.11000%
  Failure Rate: 26.89000%
  Average TTFB: 51.030573ms
  Average TTLB: 51.820745ms
         Delta: 790.172µs

Cool! Looks like the reported failure rate closely matches to what our dummy API was invoked with. However, changes in the delay interval and how it affects the TTFB and TLLB is a bit more subtle since concurrent requests also slow server response times too.

For example, if we restart the dummy API with a delay interval of 0ms, and rerun the above flood, we'll get an average TTxB of about 4xms, not quite 25ms (the average of 0ms and 50ms) less than the 51ms TTFxB above. In fact, the delta between the TTLB and TTFB seems to increase if there's no delay interval! Since the delay is just implemented as a sleep, the most likely explanation is the OS is dedicating the CPU cycles from the sleeping goroutines to accepting more concurrent connections instead. This delay increases TTFB, but decreases the relative TTLB. Very cool!

TODO

• add support for retrying failed requests.

• add more information about the HTTP request (e.g. cover all of the events supported by httptrace.ClientTrace).

• abstract the flooder's request-per-second parameter into a batch-size and interval paremeter, so that users can have more control over the flood rate.

• add a pipeline for building and pushing the images up to a Docker registry.