alecharp.fr

Get videos from Youtube with Docker

Last week I created my first docker image to be able to get videos from youtube without having to install anything on my computer.

Youtube-dl

For a year or two, I used youtube-dl to download any videos from the video platform in order to have a offline version of any videos I’d like to watch. This is very useful to watch them in public transport or when you have a bad internet connection.

As I recently change of macbook, I tried to install as few software as possible. The idea was to remove any npm/bower crap. I even extend this to youtube-dl. Why? To reduce the possible issues with brew upgrade or any conflicts with other package manager.

Docker-ization

There are some youtube-dl based images that can be found on the docker-registry. But I wanted to create and offer something more. Not that I don’t trust unofficial images, but I wanted to base this one on an official one. So let’s go for a debian:sid.

I could have just install the youtube-dl binary and set the ENTRYPOINT on it. But, as I said, I wanted to offer something more. So I joined the dl.sh script which will be executed to download the videos. Having such a entrypoint will also enable to add new features on-top of youtube-dl.

That is what I’ve done on the version 1.1. The first version (1.0) was only able to download the video and audio from the link. On version 1.1, there is a --audio parameter to specify that you only want the audio of the following link.

Adding new features will be done only on the dl.sh script without changing the Dockerfile. So the only modifications that will be done on the Dockerfile would be the upgrade of curl, python or ffmpeg.

I can even change the entrypoint from dl.sh to any other script written in any other language, the end users shouldn’t notice.

From unstable to stable and reproductible

I spoke about this image with my friend Olivier Croissier and he said:

Your image is not really reproductible

And he’s right. Again.

See on my Dockerfile, I run apt-get update && apt-get upgrade. So from one build to another, I can have a core package version that have change and introduce a bug. It is the same problem when I install curl, python2.7 and ffmpeg. Even worst I get the lastest from youtube-dl.

So to make my image stable and reproductible, I have to set the version of each package I want to install. So that I’m sure that from one build to another, without changing the Dockerfile, the package used will be the same.

But if you are “just” using the image, you can use the tags (1.0, 1.1, etc.) and those images are fix and won’t move.

Usage

So you can find the script and Dockerfile on Github: alecharp/get-videos. And the docker image on the registry: alecharp/get-video.

To use the my image:

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docker pull alecharp/get-videos:1.1
docker run --rm -v "$(pwd)":/downloads alecharp/get-videos [--audio] URL [ [--audio] URL]

All the files are downloaded into the volume /downloads of the container. When docker 1.5 will be released, the flag --read-only will be usefull to be sure to store the files on your host, not on the container.

The files are stored into a folder named after the uploader name.

On my git repository, I’m using something like the git-flow process so:

  • master is stable
  • dev is latest and unstable

and I create a tag (git and docker) for every release. I add the changelog in the README.md file that you can see on both Github and Docker registry.

Conclusion

This is my first Docker image. It is not the most useful image of all time as some others already offer to use youtube-dl. But I hope you will like it.