Decoy

A Go library and CLI tool for generating and ingesting mock/synthetic data using Go templates.

CLI

Features

• Template Engine - Generate dynamic data using Go's text/template. See Template Engine section.
  • Use built-in functions like random generation, probability, counters, and more.
• Runner Engine - Ingest generated data using implemented Runners. See Runner Engine section.
  • Concurrent Execution - You can execute the runner n times using multiple goroutines.
• Persistence - You can save Templates and Runners to reuse later.
• Mock server - Create mock servers using the Template Engine and the OpenAPI Specification.

Installation

go install github.com/aaron70/decoy/cmd/decoy@latest

Or build from source:

git clone https://github.com/aaron70/decoy.git
cd decoy
go build -o decoy ./cmd/decoy/main.go

Quick Start

Store a template

decoy template store greet -t 'Hello, {{ coalesce .Name "World" }}!'

Parse the template

decoy template parse greet --data '{ "Name": "Doe" }'

Store a runner

decoy runner store echo -c 'echo User said: "{{ .template }}"' 

Execute the runner

decoy runner run cmd echo greet -v Name=Doe

Start a REST server

decoy server rest start -f ./spec.yaml

Explore the commands

decoy template --help
decoy template parse --help
decoy runner --help
decoy runner run --help
decoy server --help
decoy server start --help

Library Usage

package main

import (
    "fmt"
    "github.com/aaron70/decoy/pkg/decoy"
)

func main() {
    d, _ := decoy.NewDecoyWithSeed(42)

    result, _ := d.ParseTemplateString(
        `{"id": {{nextIncrementalInt "counter" 1 1}}, "name": "{{randomName}} {{randomLastName}}"}`,
    )
    fmt.Println(result)
}

All random generation functions (RandomInt, RandomFloat, RandomBoolean, RandomChoice, RandomText, RandomName, etc.) are available as methods on Decoy or via the decoy.RandomChoice generic function.

Documentation

• CLI Reference — Full command usage, runner engine configuration, advanced examples
• Template Functions — Complete function signatures, parameters, and examples
• Server API Reference — Decoy server API and mock server.

Configuration

Templates, runners, and server specs are stored as JSON files under ~/.config/decoy/ (or $XDG_CONFIG_HOME/decoy).