GierszeRec

A tiny Docker container to record lectures and such on headless servers. Preferrably on Fridays, 8am.

Comes with minimal Openbox, Xdummy and all the stuff to run a persistent GUI session in a container, along with OBS Studio, Chromium, ffmpeg, Mesa/llvmpipe, etc - so it's ready to record anything.

Ready-to-use images are published in the Docker Hub.

How to use

First start requires some setup:

docker pull dragoonaethis/gierszerec
docker volume create rec

docker run --name gierszerec --publish 5900:5900 --mount source=rec,target=/rec --detach dragoonaethis/gierszerec

If you'd rather build the image from scratch instead of pulling (swap the tag in docker run):

git clone https://github.com/DragoonAethis/GierszeRec.git && cd GierszeRec
docker build -t dragoonaethis/gierszerec:tag .

Confirm OBS can record audio by opening the Desktop Audio -> Cog -> Properties page. If there's a "default" device selected, it should be good to go, but you can also try playing some audio in the browser and confirm the volume meter shows activity.

Then just connect over VNC to :5900 and set up your recording session. Right-click anywhere to open the system menu - the first 3 options should be enough. If you leave the VNC session, OBS will keep recording (if you've started it, of course).

You might want to publish the VNC port to something like 127.0.0.1:5900:5900, so that only local machine users can connect to that (if you don't have a firewall, anyone will be able to connect to the container with no authentication). With the localhost publish, you can set up a SSH tunnel in your VNC client (like Remmina) to the host running that container and connect to the local port.

To pull recorded videos from the container:

• Find where the rec volume is mounted: docker volume inspect rec
• Copy/move your stuff from the mountpoint directory.

To stop the container, right-click anywhere in VNC -> Exit.

To start the container again, docker restart gierszerec - make sure OBS can record audio, for some reason PulseAudio dies every now and then. If that happens, recreate the container:

• docker kill gierszerec
• docker rm gierszerec,
• docker run ... command from the first start section.

Record with ffmpeg

If you don't have a machine powerful enough to handle OBS (for example, if running on a shared host) then you'll have to use ffmpeg (1080p, 30FPS, grabs the entire screen and PulseAudio default output, encodes on a CPU with the ultrafast preset):

ffmpeg -video_size 1920x1080 -framerate 30 \
    -f x11grab -i :0.0 \
    -f pulse -ac 2 -i default \
    -c:v h264 -preset ultrafast \
    "/rec/$(date +'%Y-%m-%e %X').mkv"

This script is also shipped as rec in the Docker image, so you can just start xterm -> rec and off you go.

Hetzner helper

If you're using Hetzner to host your stuff:

• Log into the Hetzner Cloud console.
• Create a new project to store the VMs in.
• Add SSH keys to the project with names matching the client's hostname. (The script uses the output of hostname as the SSH key name to provision the VM with.)
• Generate API keys and configure hcloud for that project.
• Use the gierszerec up|down|ssh|vnc|pull script in this repo to:
  • up: Create a new server, configure Docker and start the container described above.
  • ssh: Connect via SSH to the server.
  • vnc: Connect via VNC to the server using Remmina and a SSH tunnel.
  • pull: Download the contents of the rec Docker volume to a new local directory.
  • down: Destroy that server.

It's a fast way to quickly set up a new recorder, pull all recorded files, then tear it down. The default CPX21 image costs 0.014EUR/h, so it's pretty cheap. Note that it assumes hcloud is already configured with the context you want to use - it manages a server called GierszeRec in it.