> ## Documentation Index
> Fetch the complete documentation index at: https://www.aptible.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# How to set and modify configuration variables

Learn how to set and modify app [configuration variables](/core-concepts/apps/deploying-apps/configuration). Setting or modifying app configuration variables always restarts the app to apply the changes. Follow our [synchronize configuration and code changes guide](/how-to-guides/app-guides/synchronize-config-code-changes) to update the app configuration and deploy code using a single deployment. 

## Using the Dashboard

Configuration variables can be set or modified in the Dashboard in the following ways:

* While deploying new code by:

  * Using the [**Deploy**](https://app.aptible.com/create) tool will allow you to set environment variables as you deploy your code <img src="https://mintcdn.com/aptible/2c_c-XH-dAzVOaDu/images/config-var1.png?fit=max&auto=format&n=2c_c-XH-dAzVOaDu&q=85&s=321d06902821e61cc2531a40a5bcb944" alt="" width="2000" height="2000" data-path="images/config-var1.png" />

* For existing apps by:

  * Navigating to the respective app

  * Selecting the **Configuration** tab

  * Selecting **Edit** within Edit Environment Variables <img src="https://mintcdn.com/aptible/2c_c-XH-dAzVOaDu/images/config-var2.png?fit=max&auto=format&n=2c_c-XH-dAzVOaDu&q=85&s=ed3627d46fa098c2ca022af3d5e4f9ee" alt="" width="2000" height="1000" data-path="images/config-var2.png" />

## Using the CLI

Configuration variables can be set or modified via the CLI in the following ways:

* Using [`aptible deploy`](/reference/aptible-cli/cli-commands/cli-deploy) command

* Using the [`aptible config:set`](/reference/aptible-cli/cli-commands/cli-config-set) command

## Size Limits

A practical limit for configuration variable length is 65,536 characters.