# Dynamic Data Sources for Development/Production Environment

> Learn how to setup dynamic dev/prod environment in Holistics

:::info
Holistics supports this thanks to our ability to define [dynamic data sources](/docs/development/dynamic-data-source).
:::

:::warning Model Persistence
Dynamic Dev/Prod Environment does not support Query Model Persistence. Please check your data model persistence before using this feature.
:::

## Introduction

In a typical development workflow, you'll have several environments: Production, Development, and Staging, each using different data sources.

This document will show you how to set up this workflow in Holistics.

![Dynamic Development/Production environment](https://cdn.holistics.io/product/modeling-dev-prod-intro-20240911-268.png)

## How it works

At a high level, the data source will dynamically switch based on which branch users are on.

Holistics provides a global dynamic variable, `H.git.current_branch`, which returns the name of the current branch. 

You can then use conditional statements (if-else) to dynamically switch the database or schema name based on the branch.

### 1. Connect databases

Note that the pre-requisite of the flow is that you need to connect to all of your databases first (development, staging, production). Please refer to **[this link](/docs/connect/)** for more information.

### 2. Create a `databases.aml` file to map the datasource based on the current branch

```tsx

// This is for dynamic database use case by branch
const dynamic_db = if (H.git.is_production) {
                     'production_data_source'
                   } else if (H.git.current_branch == 'staging') {
                     'staging_data_source'
                   } else {
                     'development_data_source'
                   }

// This is for dynamic schema use case by branch                
const dynamic_schema = if (H.git.is_production) {
                         'prod'
                       } else if (H.git.current_branch == 'staging') {
                         'stg'
                       } else {
                         'dev'
                       }
```
:::info Note

The file `database.aml` will be stored in git, so please don’t store sensitive information credentials there

:::

### 3. Use the dynamic_db and dynamic_schema in datasets/models

```tsx
Model users {
	label: 'Users'
	description: 'Info about Users'
  // highlight-next-line
	data_source_name: dynamic_db  
  // highlight-next-line
	table_name: '${dynamic_schema}.revenue'
}

Dataset ecommerce {
	label: 'Ecommerce'
	description: 'Dynamic Data Source Ecom Dataset'
  // highlight-next-line
	data_source_name: dynamic_db
	models: [users, orders]
	relationships: [orders.user_id > users.id, true]
}
```

### 4. Switching branch will switch the data source name of the related models and datasets

For example:

- If you change to `develop` branch => your database will be `develop`
- If you change to `staging` branch => your database will be `staging`
- If you deploy => your project on `master` branch will use the database `production`

## Available Variables

While not exhaustive, here are some common system variables you can use:
* `H.git.current_branch`  → this will return the name of the current branch
* `H.git.is_production`  → this will return `true` when in Reporting tab, or in Development workspace with production mode enabled.