Cobalt

Cobalt is a self-hosted media downloader that runs as a separate container alongside summarize. It fetches video and audio from platforms that yt-dlp cannot handle, or situations where yt-dlp fails due to rate limits, geo-restrictions, or missing cookies.

When to Use Cobalt

Tip: For Instagram, TikTok, Twitter/X, Reddit, and Facebook, yt-dlp is the primary downloader. It is faster, requires no extra container, and supports per-platform cookie authentication. Cobalt is only used as a fallback when yt-dlp fails or does not recognize the URL.

When yt-dlp Is Better

Running Cobalt

Standalone

$
docker compose -f docker-compose.cobalt.yml up -d

This starts Cobalt on http://localhost:9000. The summarize app automatically points to this URL via the COBALT_BASE_URL environment variable.

With Proxy

If Cobalt needs to connect through a proxy (for geo-unblocking or CDN access):

1. Copy the template:

   $
   cp cobalt.proxy.env.example cobalt.proxy.env

2. Fill in your proxy credentials:

   1
   HTTP_PROXY=http://username:password@proxy-host:port/
   2
   HTTPS_PROXY=http://username:password@proxy-host:port/
   3
   NO_PROXY=localhost,127.0.0.1,cobalt,summarizer

3. Start with the proxy overlay:

   $
   docker compose -f docker-compose.cobalt.yml -f docker-compose.proxy.yml up -d

Full Stack (Summarize + Cobalt)

$
# Full stack, no proxy
$
docker compose up -d
$
$
# Full stack, with proxy
$
docker compose -f docker-compose.yml -f docker-compose.proxy.yml up -d

Docker Compose Reference

Configuration

The summarize app talks to Cobalt through the --cobalt-url flag or the COBALT_BASE_URL environment variable:

$
python -m summarizer --source "URL" --cobalt-url "http://localhost:9000"

In Docker, this is set automatically:

1
environment:
2
  - COBALT_BASE_URL=http://cobalt:9000