Blast is a simple tool for API load testing and batch jobs
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README.md

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Blast

  • Blast makes API requests at a fixed rate.
  • The number of concurrent workers is configurable.
  • The rate may be changed interactively during execution.
  • Blast is protocol agnostic, and adding a new worker type is trivial.
  • For load testing: random data can be added to API requests.
  • For batch jobs: CSV data can be loaded from local file or GCS bucket, and successful items from previous runs are skipped.

Installation

Mac

brew tap dave/blast
brew install blast

Linux

See the releases page

From source

go get -u github.com/dave/blast

Examples

Using the dummy worker to send at 20,000 requests per second (the dummy worker returns after a random wait, and occasionally returns errors):

blast --rate=20000 --workers=1000 --worker-type="dummy" --worker-template='{"min":25,"max":50}'

Using the http worker to request Google's homepage at one request per second (warning: this is making real http requests - don't turn the rate up!):

blast --rate=1 --worker-type="http" --payload-template='{"method":"GET","url":"http://www.google.com/"}'

Status

Blast prints a summary every ten seconds. While blast is running, you can hit enter for an updated summary, or enter a number to change the sending rate. Each time you change the rate a new column of metrics is created. If the worker returns a field named status in it's response, the values are summarised as rows.

Here's an example of the output:

Metrics
=======
Concurrency:      1999 / 2000 workers in use

Desired rate:     (all)        10000        1000         100
Actual rate:      2112         5354         989          100
Avg concurrency:  1733         1976         367          37
Duration:         00:40        00:12        00:14        00:12

Total
-----
Started:          84525        69004        14249        1272
Finished:         82525        67004        14249        1272
Mean:             376.0 ms     374.8 ms     379.3 ms     377.9 ms
95th:             491.1 ms     488.1 ms     488.2 ms     489.6 ms

200
---
Count:            79208 (96%)  64320 (96%)  13663 (96%)  1225 (96%)
Mean:             376.2 ms     381.9 ms     374.7 ms     378.1 ms
95th:             487.6 ms     489.0 ms     487.2 ms     490.5 ms

404
---
Count:            2467 (3%)    2002 (3%)    430 (3%)     35 (3%)
Mean:             371.4 ms     371.0 ms     377.2 ms     358.9 ms
95th:             487.1 ms     487.1 ms     486.0 ms     480.4 ms

500
---
Count:            853 (1%)     685 (1%)     156 (1%)     12 (1%)
Mean:             371.2 ms     370.4 ms     374.5 ms     374.3 ms
95th:             487.6 ms     487.1 ms     488.2 ms     466.3 ms

Current rate is 10000 requests / second. Enter a new rate or press enter to view status.

Rate?

Config

Blast is configured by config file, command line flags or environment variables. The --config flag specifies the config file to load, and can be json, yaml, toml or anything else that viper can read. If the config flag is omitted, blast searches for blast-config.xxx in the current directory, $HOME/.config/blast/ and /etc/blast/.

Environment variables and command line flags override config file options. Environment variables are upper case and prefixed with "BLAST" e.g. BLAST_PAYLOAD_TEMPLATE.

Templates

The payload-template and worker-template options accept values that are rendered using the Go text/template system. Variables of the form {{ .name }} or {{ "name" }} are replaced with data.

Additionally, several simple functions are available to inject random data which is useful in load testing scenarios:

  • {{ rand_int -5 5 }} - a random integer between -5 and 5.
  • {{ rand_float -5 5 }} - a random float between -5 and 5.
  • {{ rand_string 10 }} - a random string, length 10.

Workers

Worker is an interface that allows blast to easily be extended to support any protocol. See main.go for an example of how to build a command with your custom worker type.

Starter and Stopper are interfaces a worker can optionally satisfy to provide initialization or finalization logic. See httpworker and dummyworker for simple examples.

Examples

For load testing:

rate: 20000
workers: 1000
worker-type: "dummy"
payload-template:
  method: "POST"
  path: "/foo/?id={{ rand_int 1 10000000 }}"
worker-template:
  print: false
  base: "https://{{ .region }}.my-api.com"
  min: 10
  max: 20
worker-variants:
  - region: "europe-west1"
  - region: "us-east1"

For bulk API tasks:

# data would usually be the filename of a local CSV file, or an object in a GCS bucket. However, 
# for the purposes of this example, a CSV fragment is also accepted.
data: |
  user_name,action
  dave,subscribe
  john,subscribe
  pete,unsubscribe
  jimmy,unsubscribe
resume: true
log: "out.log"
rate: 100
workers: 20
worker-type: "dummy"
payload-template: 
  method: "POST"
  path: "/{{ .user_name }}/{{ .action }}/{{ .type }}/"
worker-template:  
  print: true
  base: "https://{{ .region }}.my-api.com"
  min: 250
  max: 500
payload-variants: 
  - type: "email"
  - type: "phone"
worker-variants: 
  - region: "europe-west1"
  - region: "us-east1"
log-data:
  - "user_name"
  - "action"
log-output: 
  - "status"

Configuration options

data

Data sets the the data file to load. If none is specified, the worker will be called repeatedly until interrupted (useful for load testing). Load a local file or stream directly from a GCS bucket with gs://{bucket}/{filename}.csv. Data should be in csv format, and if headers is not specified the first record will be used as the headers. If a newline character is found, this string is read as the data.

log

Log sets the filename of the log file to create / append to.

resume

Resume instructs the tool to load the log file and skip previously successful items. Failed items will be retried.

rate

Rate sets the initial rate in requests per second. Simply enter a new rate during execution to adjust this. (Default: 10 requests / second).

workers

Workers sets the number of concurrent workers. (Default: 10 workers).

worker-type

WorkerType sets the selected worker type. Register new worker types with the RegisterWorkerType method.

payload-template

PayloadTemplate sets the template that is rendered and passed to the worker Send method. When setting this by command line flag or environment variable, use a json encoded string.

Advanced configuration options

timeout

Timeout sets the deadline in the context passed to the worker. Workers must respect this the context cancellation. We exit with an error if any worker is processing for timeout + 1 second. (Default: 1 second).

headers

Headers sets the data file headers. If omitted, the first record of the csv data source is used. When setting this by command line flag or environment variable, use a json encoded string.

log-data

LogData sets an array of data fields to include in the output log. When setting this by command line flag or environment variable, use a json encoded string.

log-output

LogOutput sets an array of worker response fields to include in the output log. When setting this by command line flag or environment variable, use a json encoded string.

worker-template

WorkerTemplate sets a template to render and pass to the worker Start or Stop methods if the worker satisfies the Starter or Stopper interfaces. Use with worker-variants to configure several workers differently to spread load. When setting this by command line flag or environment variable, use a json encoded string.

worker-variants

WorkerVariants sets an array of maps that will cause each worker to be initialised with different data. When setting this by command line flag or environment variable, use a json encoded string.

payload-variants

PayloadVariants sets an array of maps that will cause each data item to be repeated with the provided data. When setting this by command line flag or environment variable, use a json encoded string.

Control by code

The blaster package may be used to start blast from code without using the command. Here's a some examples of usage:

ctx, cancel := context.WithCancel(context.Background())
b := blaster.New(ctx, cancel)
defer b.Exit()
b.SetWorker(func() blaster.Worker {
	return &blaster.ExampleWorker{
		SendFunc: func(ctx context.Context, self *blaster.ExampleWorker, in map[string]interface{}) (map[string]interface{}, error) {
			return map[string]interface{}{"status": 200}, nil
		},
	}
})
b.Headers = []string{"header"}
b.SetData(strings.NewReader("foo\nbar"))
stats, err := b.Start(ctx)
if err != nil {
	fmt.Println(err.Error())
	return
}
fmt.Printf("Success == 2: %v\n", stats.All.Summary.Success == 2)
fmt.Printf("Fail == 0: %v", stats.All.Summary.Fail == 0)
// Output:
// Success == 2: true
// Fail == 0: true
ctx, cancel := context.WithCancel(context.Background())
b := blaster.New(ctx, cancel)
defer b.Exit()
b.SetWorker(func() blaster.Worker {
	return &blaster.ExampleWorker{
		SendFunc: func(ctx context.Context, self *blaster.ExampleWorker, in map[string]interface{}) (map[string]interface{}, error) {
			return map[string]interface{}{"status": 200}, nil
		},
	}
})
b.Rate = 1000
wg := &sync.WaitGroup{}
wg.Add(1)
go func() {
	stats, err := b.Start(ctx)
	if err != nil {
		fmt.Println(err.Error())
		return
	}
	fmt.Printf("Success > 10: %v\n", stats.All.Summary.Success > 10)
	fmt.Printf("Fail == 0: %v", stats.All.Summary.Fail == 0)
	wg.Done()
}()
<-time.After(time.Millisecond * 100)
b.Exit()
wg.Wait()
// Output:
// Success > 10: true
// Fail == 0: true

To do

  • Adjust rate automatically in response to latency? PID controller?
  • Only use part of file: part i of j parts