Data directories

Nexus separates application code from persistent data. All data that must survive container rebuilds and updates lives outside the Docker container, on the host filesystem.

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Directory layout

/opt/nexus/                    Application code and configuration
├── .env                       Secrets and configuration (mode 600)
├── Caddyfile                  Canonical Caddyfile (edit this, not /etc/caddy/Caddyfile)
├── docker-compose.prod.yml    Docker Compose configuration
└── ...                        Application source files

/opt/nexus-data/               Persistent data (never touched by nexus-update)
├── postgres/                  PostgreSQL data volume
└── uploads/                   User-uploaded files
    ├── posts/                 Images attached to posts
    ├── avatars/               User profile pictures
    ├── covers/                User profile cover images
    ├── logos/                 Site logo, favicon, OG image
    ├── webp/                  WebP-converted versions
    │   ├── posts/
    │   ├── avatars/
    │   ├── covers/
    │   └── logos/
    └── extensions/
        └── <slug>/            Files for each installed extension

/opt/nexus-backups/            Backup archives (created by nexus-backup)
├── db_TIMESTAMP.sql.gz
└── uploads_TIMESTAMP.tar.gz

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/opt/nexus

Application code, configuration, and management scripts. This directory is updated on every nexus-update run, except for files explicitly preserved:

File	Preserved by nexus-update
.env	✓ Always preserved
docker-compose.yml	✓ Always preserved
docker-compose.prod.yml	✓ Always preserved
Caddyfile	✓ Always preserved
Everything else	✗ Overwritten

/opt/nexus/.env

Contains all secrets generated at install time. Mode 600 — readable only by root. Fields:

Variable	Purpose
PHX_HOST	The forum’s domain name
SECRET_KEY_BASE	Phoenix session encryption key
JWT_SECRET	JWT token signing secret
SESSION_SIGNING_SALT	Session cookie signing salt
DB_PASSWORD	PostgreSQL password

Back this file up and store it securely. Loss of SECRET_KEY_BASE or JWT_SECRET invalidates all active sessions.

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/opt/nexus-data

Persistent data that survives container rebuilds and nexus-update. The Docker Compose file bind-mounts this directory into the container:

• postgres/ → PostgreSQL stores its data files here. The database container reads and writes this directory directly.
• uploads/ → User-uploaded files. Mounted into the application container at /app/uploads.

This directory is never modified by nexus-update. It is your source of truth for all user-generated content.

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/opt/nexus-backups

Created by nexus-backup. Contains database dumps and upload archives. Not created until the first backup is run. See Backups for details.

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Disk space

The two directories that grow over time are:

• /opt/nexus-data/postgres/ — grows with forum activity (posts, users, indexes)
• /opt/nexus-data/uploads/ — grows with user uploads

Monitor available disk space with:

df -h /opt/nexus-data
du -sh /opt/nexus-data/uploads /opt/nexus-data/postgres

The upload directory stores both original files and WebP-converted versions, so each uploaded image occupies roughly double the space of the original.