Gorack

A Go API for calculating optimal weight plate combinations for barbell exercises. Available at https://gorack.pachevjoseph.com/v1/api

Try the web interface at https://pachev.github.io/gorack/

Features

• Calculate optimal plate combinations for any desired barbell weight
• Customize bar weight and available plates
• Get sensible defaults with common weights and standard Olympic barbell (45lb)
• Quick REST API access: /v1/api/rack?weight=335 returns instant results
• Smart optimization algorithm for finding the best plate combinations

Note: All plate values in responses represent pairs (e.g., "fortyFives": 2 means two 45lb plates on each side of the barbell)

Getting Started

Prerequisites

• Go 1.22 or later
• mise (optional but recommended for development)

Installation

Using mise (recommended)

The project includes a mise.toml configuration file for easy setup:

# Install dependencies and tools defined in mise.toml
mise install

# Build the project
mise run build

# Run the server
mise run run

Manual installation

# Get dependencies
go mod tidy

# Build the binary
go build -o ./tmp/gorack .

# Run the server
./tmp/gorack

The API will be available at http://localhost:8080/v1/api

Environment Variables

• API_PORT: Set custom port (default: 8080)

  API_PORT=9000 mise run run

API Usage

Simple GET Request

For quick calculations with default plate availability:

GET /v1/api/rack?weight=225

Response:

{
  "barWeight": 45,
  "fortyFives": 2,
  "desiredWeight": 225,
  "achievedWeight": 225,
  "message": "You got this!"
}

Customized POST Request

For calculating with specific plate availability:

curl -X POST \
  https://gorack.pachevjoseph.com/v1/api/rack \
  -H 'content-type: application/json' \
  -d '{
    "barWeight": 35,
    "fortyFives": 1,
    "thirtyFives": 2,
    "twentyFives": 2,
    "tens": 3,
    "fives": 2,
    "twoDotFives": 2,
    "desiredWeight": 255
}'

Response:

{
  "barWeight": 35,
  "fortyFives": 1,
  "thirtyFives": 1,
  "twentyFives": 1,
  "tens": 1,
  "fives": 1,
  "desiredWeight": 255,
  "achievedWeight": 255,
  "message": "You got this!"
}

Available Plate Types

The API supports the following plate types (values represent pairs):

JSON Parameter	Weight (lbs per plate)	Description
hundreds	100	100lb plates
fortyFives	45	45lb plates
thirtyFives	35	35lb plates
twentyFives	25	25lb plates
tens	10	10lb plates
fives	5	5lb plates
twoDotFives	2.5	2.5lb plates
oneDotTwoFives	1.25	1.25lb plates

Development

The project uses mise for streamlined development workflows:

# Live reload during development
mise run watch

# Run Go mod tidy
mise run tidy

# Clean build artifacts
mise run clean

How It Works

Gorack uses a greedy algorithm to calculate the optimal plate combination:

1. Start with the heaviest available plate
2. Add pairs of plates to the bar, always selecting the heaviest available option
3. Continue until reaching the desired weight or running out of suitable plates
4. Return the achieved weight and plate configuration

License

MIT