---
last_review: "2026-05-05"
last_reviewer: "-"
documented_code: [ ]
---

```{tags} developer, explanation, administrator, concept
```

# The Big Picture #

The LinkAhead application is split into one image for the SQL server and one for the LinkAhead
server itself. Both communicate with each other in a network set up by Docker Compose.

## Images ##

- **SQL**: The SQL image is based on an upstream MariaDB image, additional setup of user and database
  schema are performed later in the build process.
- **LinkAhead**: The LinkAhead image is based on Debian Stable. The build process adds the necessary
  packages and downloads and builds the LinkAhead server, including the WebUI.

## Composition ##

Docker Compose starts a container for each image and configures the runtime images for matching
settings. The `linkahead` wrapper script creates and manages the docker-compose.yml file from the
profile configuration.

### Customization ###

The customization mainly happens via the settings in the profile.yml and the custom directories
specified therein.

- **Passwords**: At the moment there are default passwords for access to the SQL server, but it is
  planned that they be replaced by random-generated password for each `docker-compose`
  instantiation. This should not be of utmost importance if it is possible to separate the SQL
  server from the rest of the host system on a network level.
- **Permanent data**: Data that is to remain beyond destruction of the containers is stored outside,
  linked inside the containers by volumes.