Getting Started

Getting Started

Welcome to Sentrie! This guide will help you get up and running with Sentrie quickly.

What is Sentrie?

Sentrie is a policy enforcement engine that allows you to define and evaluate authorization rules, access control policies, and business logic in a clear, type-safe language. It’s designed to be:

• Declarative: Define what should happen, not how
• Type-safe: Catch errors at policy definition time
• Performant: Built for production workloads with caching and optimization
• Extensible: Integrate with JavaScript modules for complex logic

Quick Start Guide

Follow these steps to get started with Sentrie:

1. Installation - Install Sentrie on your system
2. What is Policy as Code? - Understand the concepts behind Policy as Code
3. Writing your first Policy - Create your first Sentrie policy
4. Running your Policy - Learn how to test and run your policies

Your First Policy

Let’s create a simple authorization policy to get familiar with Sentrie.

1. Create a Policy Directory

mkdir my-first-policy
cd my-first-policy

2. Write Your First Policy

Create a file called auth.sentrie:

namespace com/example/auth

policy user {
  rule allow = default false when user.role == "admin" {
    yield true
  }

  export decision of allow
}

This policy:

• Defines a namespace com/example/auth
• Creates a policy called user
• Has a rule allow that returns true only for admin users
• Exports the allow decision for external evaluation

3. Start the Server

sentrie serve --pack-location .

You should see output like:

INFO Starting Sentrie server on port 7529
INFO Pack loaded: example
INFO Server ready

4. Test Your Policy

Make a request to evaluate the policy:

curl -X POST "http://localhost:7529/decision/com/example/auth/user/allow" \
  -H "Content-Type: application/json" \
  -d '{"user": {"role": "admin", "name": "alice"}}'

Response:

{
  "decision": true,
  "attachments": {}
}

Try with a non-admin user:

curl -X POST "http://localhost:7529/decision/com/example/auth/user/allow" \
  -H "Content-Type: application/json" \
  -d '{"user": {"role": "user", "name": "bob"}}'

Response:

{
  "decision": false,
  "attachments": {}
}

Understanding the Basics

Namespaces

Namespaces organize your policies hierarchically:

namespace com/example/auth
namespace com/example/billing
namespace com/example/analytics

Policies

Policies contain rules and define the context for evaluation:

policy user {
  // rules go here
}

Rules

Rules are the core of Sentrie policies. They have three parts:

1. Name: rule allow
2. Default: default false (what to return if the when condition is false)
3. When: when user.role == "admin" (condition that must be true)
4. Body: { yield true } (what to return if the condition is true)

Exports

Export rules to make them available for external evaluation:

export decision of allow

Next Steps

Now that you have a basic understanding, explore:

• Installation Guide - Detailed installation options
• Writing Your First Policy - Deep dive into policy creation
• Policy Language Reference - Complete language documentation
• CLI Reference - Command-line interface documentation

Common Patterns

Simple Authorization

policy access {
  rule allow = default false when user.role in ["admin", "editor"] {
    yield true
  }

  export decision of allow
}

Resource-Based Access

policy resource {
  rule canRead = default false when user.role == "admin" or resource.owner == user.id {
    yield true
  }

  rule canWrite = default false when user.role == "admin" {
    yield true
  }

  export decision of canRead
  export decision of canWrite
}

Conditional Logic

policy pricing {
  rule calculatePrice = default 0 {
    let basePrice = product.price
    let discount = user.isPremium ? 0.1 : 0.05
    let finalPrice = basePrice * (1 - discount)

    yield finalPrice
  }

  export decision of calculatePrice
}

Troubleshooting

Common Issues

Policy not found: Make sure your namespace and policy names match exactly in the URL path.

Invalid JSON: Ensure your request body is valid JSON and matches the expected structure.

Server won’t start: Check that port 7529 is available, or use --port to specify a different port.

Getting Help

• Check the Language Reference for syntax help
• Look at the CLI Reference for command options
• Visit our GitHub repository for examples and issues