Replication & backup with Litestream

SQLite is a single file — back it up by copying it. But for production, you want continuous replication: every WAL frame streamed to object storage so you can restore to any point in time, with zero downtime. Litestream does exactly this, and it works seamlessly with Dulak’s WAL-mode bun:sqlite database.

How it works

Dulak (Bun) → app.sqlite (WAL mode)
                    ↓
              Litestream daemon
                    ↓
              S3 / R2 / MinIO

Litestream runs as a sidecar process alongside Dulak. It tails the WAL file and streams changes to your replica — no app code changes, no downtime, no locks. If the server dies, you restore from the replica and restart.

Install

# Linux (amd64)
curl -L https://github.com/litestream/litestream/releases/latest/download/litestream-linux-amd64 -o /usr/local/bin/litestream
chmod +x /usr/local/bin/litestream

Or with Homebrew on macOS for local testing:

brew install litestream

Configure

Create /etc/litestream.yml:

dbs:
  - path: /opt/dulak/data/app.sqlite
    replicas:
      - url: s3://your-bucket/dulak
        # S3-compatible endpoints work too: Cloudflare R2, MinIO, Backblaze B2
        # For R2:  s3://your-bucket@dulak-backup.<account-id>.r2.cloudflarestorage.com/dulak
        # For B2:  s3://your-bucket@s3.us-west-000.backblazeb2.com/dulak
        sync-interval: 1s

Credentials go in environment variables, not the config file:

export LITESTREAM_ACCESS_KEY_ID=...
export LITESTREAM_SECRET_ACCESS_KEY=...

Or put them in /opt/dulak/.env.litestream and source it from the systemd unit.

Run as a systemd service

/etc/systemd/system/litestream.service:

[Unit]
Description=Litestream replication
After=network.target

[Service]
Type=simple
EnvironmentFile=/opt/dulak/.env.litestream
ExecStart=/usr/local/bin/litestream replicate -config /etc/litestream.yml
Restart=always
RestartSec=3

[Install]
WantedBy=multi-user.target

sudo systemctl enable --now litestream
sudo systemctl status litestream

Litestream starts after Dulak and tails the WAL file. If Dulak restarts, Litestream picks up where it left off — no coordination needed.

Run with Docker

If you deploy Dulak with Docker, run Litestream as a sidecar in docker-compose.yml:

services:
  app:
    build: .
    ports:
      - "127.0.0.1:4000:4000"
    env_file: .env
    volumes:
      - ./data:/app/data
    restart: unless-stopped

  litestream:
    image: litestream/litestream:latest
    command: replicate -config /etc/litestream.yml
    environment:
      LITESTREAM_ACCESS_KEY_ID: ${LITESTREAM_ACCESS_KEY_ID}
      LITESTREAM_SECRET_ACCESS_KEY: ${LITESTREAM_SECRET_ACCESS_KEY}
    volumes:
      - ./data:/data:ro          # read-only access to the SQLite file
      - ./litestream.yml:/etc/litestream.yml:ro
    restart: unless-stopped
    depends_on:
      - app

Update the path in litestream.yml to /data/app.sqlite (the volume mount path inside the Litestream container).

Restore

If your server dies or the database file corrupts:

# Stop Dulak first
sudo systemctl stop dulak

# Restore from the replica
litestream restore -o /opt/dulak/data/app.sqlite s3://your-bucket/dulak

# Start Dulak
sudo systemctl start dulak

You can also restore to a specific point in time:

litestream restore -o /opt/dulak/data/app.sqlite \
  -timestamp 2026-08-08T10:30:00Z \
  s3://your-bucket/dulak

What Litestream does NOT do

Litestream is replication, not high availability. It protects against data loss — not against downtime. If the server dies, you restore to a new server and restart. For zero-downtime failover, you need multiple Dulak instances behind a load balancer with a shared database (Postgres, MySQL) — that is the swap point where SQLite is no longer the right tool.

Cost

Litestream is free, open-source, and self-hosted. You pay only for object storage:

• Cloudflare R2: $0.015/GB/month, no egress fees — cheapest option
• AWS S3: $0.023/GB/month + egress
• Backblaze B2: $0.006/GB/month — cheapest storage, egress is free up to 3× storage cost

A Dulak database with 10K users and uploads metadata is likely under 100MB — that is less than $0.01/month on any provider.