> For the complete documentation index, see [llms.txt](https://mercure-technologies.gitbook.io/xprem/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mercure-technologies.gitbook.io/xprem/installation-guide/database-configuration.md).

# Database configuration

The xprem control plane uses PostgreSQL as its primary data store: updates, branches, channels, and rollouts all live there.

Before you begin, you need a running PostgreSQL instance that your xprem deployment will be able to reach.

### Creating the database

The server runs its schema migrations itself, but never creates the database.\
If your provider didn't already create a database for you, you can create one manually:

```shellscript
psql "postgresql://{{USER}}:{{PASSWORD}}@{{HOST}}:{{PORT}}/postgres" \
  -c 'CREATE DATABASE xprem;'
```

{% hint style="info" %}
This guide uses `xprem` as the database name, but any name works
{% endhint %}

Note down the connection string for the database you just created: you'll set it as `DB_URL` in your environment:

```shellscript
DB_URL=postgresql://{{USER}}:{{PASSWORD}}@{{HOST}}:{{PORT}}/xprem
```

### Generate the master key

xprem signs every update it serves. Your app embeds the matching certificate at build time and verifies that signature before applying an update so a compromised bucket or CDN can't push malicious code to your users.

The private signing keys live in your PostgreSQL database, encrypted at rest with your master key.

{% hint style="warning" %}
**Do not lose your master key. I**t is the only thing that can decrypt your signing keys, and there is no recovery path. Recovering means generating new signing keys, rebuilding your app, and shipping it through the app stores.
{% endhint %}

To generate the master key please run:

```shellscript
openssl rand -base64 32
```

You'll set this value as `DB_KEYS_MASTER_KEY_B64` in your environment

{% hint style="info" %}
If you are using AWS Secrets Manager, create a new key on AWS with this value and store the key id as `AWSSM_DB_KEYS_MASTER_KEY_SECRET_ID`
{% endhint %}


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