How to Work with Images

You can use your own images in a Learning Lab by uploading them to a folder /assets/images, one per Lab. Then reference the image in your Markdown file with a relative path, such as ![alt tab](assets/images/filename.png).

As for image file types, we prefer PNG but animated GIFs are also allowed.

We've found that asciinema saves files in .cast and then you can use asciicast2gif within a Docker container to do the conversion to GIF.

asciinema intro

asciinema lets you easily record terminal sessions and replay them in a terminal as well as in a web browser.

Install latest version:

sudo pip3 install asciinema

Record your first session:

asciinema rec first.cast

Now replay it with double speed:

asciinema play -s 2 first.cast

Or with normal speed but with idle time limited to 2 seconds:

asciinema play -i 2 first.cast

You can pass -i 2 to asciinema rec as well, to set it permanently on a recording. Idle time limiting makes the recordings much more interesting to watch. Try it.

If you want to watch and share it on the web, upload it:

asciinema upload first.cast

asciicast2gif intro

Pull the image: docker pull asciinema/asciicast2gif

Use it like this: docker run --rm -v $PWD:/data asciinema/asciicast2gif [options and arguments...]

You need to mount some local directory at /data so input and output files can be accessed by the container. Mounting current working directory ($PWD) makes most sense in majority of cases.

For example, generating GIF from local file, with double speed and Solarized theme:

docker run --rm -v $PWD:/data asciinema/asciicast2gif -s 2 -t solarized-dark 216176.cast demo.gif

Running the above, long command can get old very quickly. Creating a shell alias may be a good idea:

alias asciicast2gif='docker run --rm -v $PWD:/data asciinema/asciicast2gif'