dotcom-arcade/docs/10-features/13-streaming.md

Streaming

Overview

Some Flashpoint games can't run in a browser at all: Java applets, Shockwave and Director movies, and Flash games that need the real Flash Player. Dotcom Arcade runs each one natively on the server and streams it into the game page. Every player gets their own container, which is removed when they leave.

Streaming is optional and off by default. Without it, those games' pages say they need the Flashpoint Launcher.

How it works

• The app (backend/) asks the session manager whether each game can be streamed. It then offers Play, plus the Ruffle / original Flash Player switch for Flash games.
• The session manager (streaming/session-manager) starts one streamer container per session through the Docker socket, and proxies the browser's connection to it at /stream/<id>/. The app forwards /stream/ to it.
• The streamer (streaming/streamer) launches the game the way Flashpoint's Linux launcher does, and streams the screen and sound with Selkies. The display is sized to the game: a Director stage, a SWF's stage, or a page's applet or largest embed.

A session is removed if nothing connects within 2 minutes, or 30 seconds after the player's last connection closes. At most MAX_SESSIONS run at once. Games save to files inside the container; those are sent back to the player's browser as they change, and restored at the start of the next session (see Game Saves).

Implementation details are in streaming/README.md and streaming/streamer/README.md.

Requirements

• Infinity for Linux's software. The streamer runs Flashpoint's Linux builds of the game server, Java, Wine and the Flash and Shockwave players. Ultimate's archives only include the Windows builds. Download Flashpoint Infinity for Linux from Flashpoint's downloads page and pass it to scripts/setup-flashpoint.sh --infinity, which adds the software without replacing anything.
• HTTPS. Browsers only allow the video decoder Selkies uses on secure pages.
• A server with CPU to spare. Every player streaming at once has a container running the game and encoding its video on the CPU. Plan on roughly 1 to 2 CPU cores and 1 GB of RAM each, and a few Mbps of upload. Set MAX_SESSIONS so the server isn't overloaded.

Enabling it

Add to .env:

COMPOSE_PROFILES=streaming
STREAMING_API_TOKEN=<output of: openssl rand -hex 32>

Then run docker compose up -d --build. This builds the session manager and streamer images and starts the session manager. The app reaches the session manager's internal API at http://session-manager:8080, which the compose file sets up.

Variable	Default	Description
STREAMING_API_TOKEN	-	Shared secret between the app and the session manager; required
STREAMING_API_URL	http://session-manager:8080	Session manager's internal API
STREAMING_STREAM_URL	http://session-manager:8081	Where the app proxies /stream/ to
MAX_SESSIONS	4	Most streams running at once
STREAM_PLATFORMS	Java,Shockwave,Flash	Platforms offered for streaming

Reverse proxy

The app proxies /stream/ to the session manager itself, so no extra route is needed. A reverse proxy in front of the app must still:

• pass WebSocket upgrades;
• allow long-lived connections, at least as long as a play session;
• not buffer responses, which would hold back the save-sync event stream.

With nginx:

location / {
    proxy_pass http://127.0.0.1:80;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
    proxy_set_header Host $host;
    proxy_buffering off;
    proxy_read_timeout 1h;
}

If another proxy sits in front of this one, it needs the same. A stream that connects and then immediately fails with HTTP 400 usually means a proxy in the chain doesn't pass the WebSocket upgrade.

Security

The session manager holds the Docker socket, which is effectively root on the host. It publishes no ports; only the app reaches it, on the compose network. Streamer containers run on an internal network with no internet access, reachable only from the session manager.

Troubleshooting

docker compose logs session-manager shows each session as it's created, becomes ready (with how long it took) and is removed, with the reason. When a streamer fails to start, the log says why: its exit code and its last lines of output. The app then reports "game failed to start" to the player.

• No "Original Flash Player" button, or "needs the Flashpoint Launcher" on Java and Shockwave games. The session manager isn't running, the tokens don't match, or it can't resolve the game's launcher; check that Infinity's software is installed. Ask it directly from the app's container:

  docker compose exec app sh -c 'curl -s -o /dev/null -w "%{http_code}\n" \
    -H "Authorization: Bearer $STREAMING_API_TOKEN" \
    http://session-manager:8080/games/<game id>'
  

  200 means the game can be streamed; 422 means it can't.

• The stream stays black or disconnects at once. Check that the page is on HTTPS, and that your proxy passes WebSocket upgrades.