> For the complete documentation index, see [llms.txt](https://docs.glbnxt.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.glbnxt.com/configure-glbnxt/platform-configuration/application-management/my-apps/environment-variable-rules.md).

# Environment variable rules

{% hint style="info" icon="user-lock" %}
**Role-based access**

What each role can do on this page. Roles are assigned in [User management](/configure-glbnxt/platform-configuration/user-management.md).

| Administrator                                  | Moderator                                 | User                                      |
| ---------------------------------------------- | ----------------------------------------- | ----------------------------------------- |
| <i class="fa-check">:check:</i> Read and write | <i class="fa-xmark">:xmark:</i> No access | <i class="fa-xmark">:xmark:</i> No access |
| {% endhint %}                                  |                                           |                                           |

***

What the platform accepts for an application's environment variables, and how the values are stored. For the steps to set them, see [Set environment variables](/configure-glbnxt/platform-configuration/application-management/my-apps/set-environment-variables.md).

### Per application

An application may have at most **50** environment variables.

### Names

| Rule               | Value                                     |
| ------------------ | ----------------------------------------- |
| Allowed characters | Letters, numbers and underscores          |
| First character    | A letter or an underscore, never a number |
| Maximum length     | 128 characters                            |
| Reserved           | Names beginning `GLBNXT_`                 |
| Duplicates         | Refused within one application            |

Names are case-sensitive, and `DATABASE_HOST` and `database_host` are two different variables. That is how the container reads them, so it is how the platform treats them. The reserved prefix is checked without regard to case, so `glbnxt_url` is refused as well as `GLBNXT_URL`.

`GLBNXT_` is reserved for variables the platform supplies itself. Reserving the prefix means one of your variables can never replace one of ours.

### Values

| Rule           | Value                                     |
| -------------- | ----------------------------------------- |
| Type           | Text, always                              |
| Maximum length | 4000 characters                           |
| Lines          | One. A value may not contain a line break |
| Empty          | Allowed                                   |

A value is always handed to your container as text. If you set `REPLICAS` to `16`, your application receives the string `16`, not a number; this is how environment variables work everywhere, and it is worth remembering if your application reads them without converting.

An empty value is a legitimate setting and is not the same as not setting the variable at all.

### How the values are stored

{% hint style="warning" %}
**Values are stored as plain text. Anyone who can open the application in the portal can read them**, including GLBNXT support staff, who need to see them in order to help you.

**Do not put credentials, API keys or tokens in an environment variable.**
{% endhint %}

### When a change takes effect

Adding, changing or removing a variable replaces the running container. The application restarts and keeps its address. Nothing takes effect until you choose **Save and restart**.

### How the rules are checked

The form warns you as you type when a name or value breaks a rule. The platform then validates every variable when you save, and again during the deployment. A variable that fails validation is not applied, and the message tells you which one to fix: under its row for a single variable, or on the card for the list as a whole, such as the 50-variable limit.


---

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