⏲️ fake-time-series

A flexible CLI tool and library for generating fake time series data. Perfect for testing, development, and demonstration purposes.

• ✅ Generate realistic time series data with customizable data shapes.
• ✅ Support for human-readable time ranges like "3 days ago" or "1 year ago" or "2024-6-30"
• ✅ Send data to HTTP endpoints.
• ✅ Fine-grained control over data generation with batch size and interval settings
• ✅ Built-in randomization features for more realistic data patterns.
• ✅ Simple configuration via JavaScript/ESM config files.

📡 Installation

npm install fake-time-series

yarn add fake-time-series

pnpm add fake-time-series

👋 Hello there! Follow me @linesofcode or visit linesofcode.dev for more cool projects like this one.

🚀 Getting Started

fake-time-series generate --startTime "1 week ago" --endTime "1 day ago"

Send generated data to an endpoint:

fake-time-series send --sink-url "http://localhost:3000/api/ingest" --startTime "3 months ago" --endTime "1 month ago"

🛠️ Configuration

Config File

The tool supports configuration through a JavaScript/ESM config file. By default, it looks for fake-time-series.config.mjs in the current directory.

A sample config file:

// fake-time-series.config.mjs
export const options = {
  startTime: "3 weeks ago",
  minInterval: "5s",
  maxInterval: "30s",
  maxBatchSize: 20,
  sinkUrl: "http://localhost:3000/api/ingest",
  headers: {
    "Authorization": "Bearer your-token",
    "Content-Type": "application/json"
  },
  shapes: {
		temperature: () => ({
			sensorId: Math.random().toString(36).substring(2, 15),
			value: Math.random() * 100,
		}),
	},
};

Shapes

Shapes are functions that return a data point. They can be used to generate realistic data for your specific use case.

Each shape function is identified by a key in the shapes object in the config file. Each shape function accepts the current timestamp and returns a data point, this can be a single value or a more complex object.

For example, the following shape function generates a random temperature value between 0 and 100 for a given timestamp:

// fake-time-series.config.mjs
export const config = {
	shapes: {
		temperature: (timestamp) => ({
			sensorId: Math.random().toString(36).substring(2, 15),
			value: Math.random() * 100,
		}),
	},
};

Specify a custom config path:

fake-time-series generate --config ./custom-config.mjs

Time Formats

The tool supports various time formats for startTime and endTime:

Relative Times

• Simple offsets: -1 day, -30 minutes, -12 hours, -1 week, 1 day ago, 30 minutes ago
• Multiple units: -1 day 6 hours, -2 weeks 3 days, 1 week 2 days ago
• Special keywords: now, today, yesterday

Absolute Times

• ISO 8601: 2024-01-15T10:30:00Z
• Date strings: 2024-01-15, 15-01-2024
• Time with timezone: 2024-01-15T10:30:00-05:00

Interval Formats

For minInterval and maxInterval:

• Seconds: 5s, 30s
• Minutes: 1m, 5m
• Hours: 1h, 12h
• Days: 1d
• Milliseconds: 1234567890

🔧 Options

Option	Description	Default
startTime	Start time of the series	-1 day
endTime	End time of the series	now
minInterval	Minimum interval between points	1s
maxInterval	Maximum interval between points	10s
maxBatchSize	Maximum points per batch	10
batchSizeRandomization	Enable random batch sizes	true
intervalRandomization	Enable random intervals	true
batchReverseProbability	Chance to reverse batch order	0.5
batchShuffleProbability	Chance to shuffle batch	0.4
intervalSkewProbability	Chance of interval skewing	0.8
concurrency	Max concurrent requests (send only)	10
sinkUrl	Endpoint URL (send only)	required
headers	Request headers (send only)	{"Content-Type": "application/json"}

Examples

Generate data for the last 3 days:

fake-time-series generate --startTime "-3 days"

Generate data with specific intervals:

fake-time-series generate --minInterval "30s" --maxInterval "5m"

Send data with custom headers:

fake-time-series send \
  --sink-url "http://localhost:3000/api/ingest" \
  --headers '{"Authorization": "Bearer token123"}'