Goku

Goku is a high-performance, scalable HTTP load-testing tool designed for benchmarking and performance analysis of web services. Inspired by tools like Drill and Vegeta, Goku offers modern features and simplicity for engineers to simulate and analyze traffic efficiently.

Features

• Fast and scalable HTTP load testing
• Real-time live stats during long tests
• Rate limiting (--rps) for constant-rate load profiles
• Multi-step sequential scenarios (multiple endpoints per test)
• Variable templating in URLs and bodies ({{uuid}}, {{seq}}, {{random_int}}, …)
• Built-in authentication (Bearer token, Basic auth)
• ASCII latency histogram in text output
• compare subcommand to diff two benchmark runs
• Output to file (--output-file) and per-request log (--results-log)
• HTTP/1.1, HTTP/2 support
• Multiple output formats: text, json, csv
• MCP (Model Context Protocol) server for LLM/agent integration

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Install CLI

Automatic download (Linux, OSX, WSL)

curl -sSL https://raw.githubusercontent.com/jcaromiq/goku/v3.0.0/scripts/install.sh | sh

Using Cargo

cargo install goku-bench
goku --version

Manual download

Go to the Goku's GitHub Releases page and download the latest .tar.gz for your system:

• Linux (x86_64, arm64)
• macOS (x86_64)
• Windows (x86_64)

From source

cargo build --release

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MCP (Model Context Protocol) Support

Goku integrates with the Model Context Protocol (MCP) — use Goku programmatically from any LLM agent or MCP-aware client.

What this enables

• Use Goku from an LLM or AI agent — no manual CLI usage required.
• Combine load testing with automated workflows: trigger a test, gather metrics, and analyze results from within an agent or script.
• Seamless integration into broader toolchains and agentic pipelines.

Example usage with an LLM

Once Goku is registered as an MCP tool, you can ask your LLM:

"Run a load test on https://api.example.com/users with 50 concurrent clients for 30 seconds using HTTP/2, and give me the p95 and p99 latency."

The LLM will call the run_benchmark MCP tool and return the full structured report.

Install MCP server

# Automatic download
curl -sSL https://raw.githubusercontent.com/jcaromiq/goku/v3.0.0/scripts/install_mcp.sh | sh

# Or via Cargo
cargo install goku-mcp

MCP tool: run_benchmark

The MCP server exposes a single unified tool with the following parameters:

Parameter	Type	Required	Description
target	string	✅	URL with optional method prefix. E.g. "POST http://api.example.com/users"
clients	number	✅	Number of concurrent workers
requests	number	—	Total requests (ignored when duration_secs is set)
duration_secs	number	—	Test duration in seconds (alternative to requests)
body	string	—	Request body for POST/PUT/PATCH
headers	string[]	—	Headers in "Name:Value" format
http2	boolean	—	Use HTTP/2 prior knowledge
ramp_up	number	—	Seconds to spread worker start
timeout_ms	number	—	Request timeout in ms (default: 30000)
insecure	boolean	—	Accept invalid TLS certificates
rps	number	—	Max requests per second (rate limiting)

Returns a full JSON report with all latency percentiles, throughput, and status code breakdown.

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Versioning

CLI is versioned with SemVer v2.0.0.

Contributing

See CONTRIBUTING.md.

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Usage manual

Usage: goku [OPTIONS] --target <TARGET>
       goku compare <BASELINE> <CANDIDATE>

Options:
  -v, --verbose                        Runs in verbose mode
  -t, --target <TARGET>                URL to request. Format: [METHOD] <url>  [default: GET]
                                       Example: "POST http://localhost:3000/api"
  -r, --request-body <REQUEST_BODY>    Path to file to use as request body
  -c, --clients <CLIENTS>              Number of concurrent workers [default: 1]
  -i, --iterations <ITERATIONS>        Total number of requests [default: 1]
  -d, --duration <DURATION>            Duration of the test in seconds (alternative to --iterations)
      --headers <HEADERS>              Headers in "Name:Value" format (repeatable)
      --scenario <SCENARIO>            Path to a YAML scenario file
      --timeout <timeout_ms>           Request timeout in ms [default: 30000]
      --http2                          Enable HTTP/2 prior knowledge
      --ramp-up <seconds>              Seconds to spread the start of workers
      --rps <RPS>                      Max requests per second across all clients
      --output <text|json|csv>         Output format [default: text]
      --output-file <PATH>             Write results to file instead of stdout
      --results-log <PATH>             Write per-request CSV log (timestamp, status, latency)
      --live-stats <seconds>           Print live stats every N seconds during the test
      --insecure                       Accept invalid/self-signed TLS certificates
      --auth-bearer <TOKEN>            Set Authorization: Bearer <TOKEN> header
      --auth-basic <USER:PASS>         Set Authorization: Basic <base64> header
      --pool-idle-timeout <seconds>    Connection pool idle timeout [default: 90]
      --disable-keepalive              Disable HTTP keep-alive / connection reuse
  -h, --help                           Print help
  -V, --version                        Print version

Subcommands:
  compare <BASELINE> <CANDIDATE>       Compare two JSON result files and show a diff table

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Flag reference

--target -t

Specifies the HTTP method and URL. Defaults to GET if no method is provided.

goku --target "GET http://localhost:3000/"
goku --target "POST http://localhost:3000/api"
goku --target http://localhost:3000          # implicit GET

--request-body -r Optional

Path to a file whose contents will be sent as the request body.

--clients -c

Number of concurrent workers. Defaults to 1.

--iterations -i

Total number of requests to perform across all workers. Defaults to 1. Cannot be used together with --duration.

--duration -d

Run the test for a fixed number of seconds instead of a fixed request count.

--headers Optional

Add one or more request headers. Repeatable. Format: Name:Value.

goku --headers Content-Type:application/json --headers X-Api-Key:secret ...

--http2 Optional

Force HTTP/2 prior knowledge (skips HTTP/1.1 upgrade negotiation).

--ramp-up Optional

Spread the start of workers over N seconds to simulate a gradual traffic spike.

--rps Optional

Limit the total requests per second across all clients. Useful for constant-rate load profiles (similar to Vegeta).

goku -c 10 -i 10000 --rps 200 --target http://localhost:3000

--output Optional

Output format. Valid values: text (default), json, csv.

--output-file Optional

Write results to a file instead of stdout. Works with any --output format.

goku -c 50 -i 1000 --output json --output-file results.json --target http://localhost:3000

--results-log Optional

Write a per-request CSV log with columns timestamp_ms,num_client,execution,status,latency_ms.

goku -c 50 -i 1000 --results-log requests.csv --target http://localhost:3000

--live-stats Optional

Print partial metrics (requests, RPS, p50, p95) to stderr every N seconds while the test runs.

goku -c 50 --duration 60 --live-stats 5 --target http://localhost:3000
  [live] requests=1250 rps=250.0 p50=45ms p95=120ms

--insecure Optional

Accept invalid or self-signed TLS certificates. Off by default.

--auth-bearer Optional

Inject an Authorization: Bearer <TOKEN> header automatically.

goku --auth-bearer "eyJhbGci..." --target http://api.example.com

--auth-basic Optional

Inject an Authorization: Basic <base64> header from user:password credentials.

goku --auth-basic "admin:secret" --target http://api.example.com

--pool-idle-timeout Optional

Idle timeout for pooled connections in seconds. Defaults to 90.

--disable-keepalive Optional

Disable HTTP keep-alive and connection reuse entirely.

--scenario Optional

Path to a YAML scenario file. When used, all other flags (except --output) are ignored and settings are read from the file.

compare Subcommand

Compare two benchmark JSON result files and show a colored diff table:

goku compare before.json after.json

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Scenario file format

target: POST http://localhost:3000/
clients: 50
requests: 1000
duration: 60          # alternative to requests
http2: true
ramp_up: 5
rps: 500              # optional rate limit
output: json
insecure: false
live_stats: 10        # print live stats every 10s
pool_idle_timeout: 30
disable_keepalive: false

headers:
  - key: "Content-Type"
    value: "application/json"
  - key: "X-Api-Key"
    value: "secret"

body: '{"firstName": "Terry", "lastName": "Medhurst", "age": 50}'

# Optional: built-in authentication
auth:
  type: bearer
  token: "my-token"

# Optional: write results to a file
output_file: results.json
results_log: requests.csv

Multi-step scenarios

Run multiple endpoints sequentially per worker:

clients: 20
duration: 60

steps:
  - target: "GET http://api.example.com/users"
  - target: "POST http://api.example.com/orders"
    body: '{"item": "widget", "qty": 1}'
    headers:
      - key: "Content-Type"
        value: "application/json"
  - target: "GET http://api.example.com/orders/latest"

Each worker executes all steps in order, repeating the sequence for the duration of the test.

Variable templating

Use dynamic placeholders in URLs and bodies:

Variable	Description
{{seq}}	Sequential request number
{{client}}	Worker ID
{{timestamp}}	Unix timestamp in ms
{{uuid}}	Pseudo-random UUID v4
{{random_int(min,max)}}	Random integer in [min, max]

goku -c 10 -i 100 \
  --target "GET http://api.example.com/users/{{random_int(1,500)}}"

goku -c 10 -i 100 \
  --target "POST http://api.example.com/events" \
  --request-body body.json
# body.json: {"id": "{{uuid}}", "seq": {{seq}}, "ts": {{timestamp}}}

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Examples

Simple targets

goku --target "GET http://localhost:3000"
goku --target http://localhost:3000?foo=bar
goku -c 50 -i 1000 --target http://localhost:3000
goku -c 50 --duration 60 --target http://localhost:3000

With custom headers

goku --target "GET http://localhost:3000" \
     --headers Content-Type:application/json \
     --headers X-Api-Key:secret

With request body

goku -c 50 -i 1000 -r body.json --target "POST http://localhost:3000"

With authentication

goku --auth-bearer "my-token" -c 20 -i 500 --target "GET http://api.example.com/protected"
goku --auth-basic "admin:pass" -c 10 -i 100 --target "GET http://api.example.com/admin"

Rate-limited test

goku -c 20 --duration 60 --rps 200 --target http://localhost:3000

With ramp-up and JSON output to file

goku -c 100 -i 5000 --ramp-up 10 --output json --output-file results.json --target http://localhost:3000

Compare two runs

goku -c 50 -i 1000 --output json --output-file before.json --target http://localhost:3000
# deploy new version...
goku -c 50 -i 1000 --output json --output-file after.json --target http://localhost:3000
goku compare before.json after.json

Output (Text)

Concurrency level    50
Time taken           4 seconds
Total requests       1000
Requests/sec         250.00 req/s
Mean                 169.90 ms
Min                  5 ms
Max                  415 ms
p50 (median)         155 ms
p95                  319 ms
p99                  360 ms
p99.9                367 ms

Status codes
  2xx  998
  5xx  2

Latency distribution
      10ms  ████████████████████████████████████████  450
      25ms  █████████████████████████                 280
      50ms  ████████████████                          150
     200ms  ████████                                   80
     415ms  ██                                         40

Output (JSON)

{
  "concurrency": 50,
  "duration_secs": 4.12,
  "total_requests": 1000,
  "requests_per_sec": 242.72,
  "mean_ms": 169.90,
  "min_ms": 5,
  "max_ms": 415,
  "p50_ms": 155,
  "p95_ms": 319,
  "p99_ms": 360,
  "p999_ms": 367,
  "status_2xx": 998,
  "status_4xx": 0,
  "status_5xx": 2,
  "status_other": 0,
  "network_errors": 0
}

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License

See LICENSE.

Donate

If you appreciate all the job done in this project, a small donation is always welcome: