Faces Demo

This is the Faces demo application. It has a single-page web GUI that presents a grid of cells, each of which should show a grinning face on a light blue background. Spoiler alert: installed exactly as committed to this repo, that isn't what you'll get -- many, many things can go wrong, and will. The point of the demo is let you try to fix things.

In here you will find:

• create-cluster.sh, a shell script to create a k3d cluster and prep it by running setup-cluster.sh.

• setup-cluster.sh, a shell script to set up an empty cluster with Linkerd, Emissary-ingress, and the Faces app.

  • These things are installed in a demo configuration: read and think carefully before using this demo as background for a production installation! In particular:

    • We deploy Emissary with only one replica of everything, using a currently-unofficial chart to also skip support for v1 and v2 Emissary CRDs.

    • We only configure HTTP, not HTTPS.

    These are likely both bad ideas for a production installation.

• DEMO.md, a Markdown file for the resilience demo presented live for a couple of events. The easiest way to use DEMO.md is to run it with demosh.

  • (You can also run create-cluster.sh and setup-cluster.sh with demosh, but they're fine with bash as well. Realize that all the #@ comments are special to demosh and ignored by bash.)

To try this yourself:

• Make sure $KUBECONFIG is set correctly.

• If you need to, run bash create-cluster.sh to create a new k3d cluster to use.

  • Note: create-cluster.sh will delete any existing k3d cluster named "faces".

• If you already have an empty cluster to use, you can run bash setup-cluster.sh to initialize it.

• Play around!! Assuming that you're using k3d, the Faces app is reachable at http://localhost/faces/ and the Linkerd Viz dashboard is available at http://localhost/

  • If you're not using k3d, instead of localhost use the IP or DNS name of the emissary-ingress service in the emissary namespace.

  • Remember, HTTPS is not configured.

• To run the demo as we've given it before, check out DEMO.md. The easiest way to use that is to run it with demosh.

Architecture

The Faces architecture is fairly simple:

• The faces-gui workload, reached on the /faces/ path, just returns the HTML and Javascript for the GUI. The GUI is a single-page webapp that displays a grid of cells: for each cell, the GUI calls the face workload.

• The face workload, reached on the /face/ path, calls the smiley workload to get a smiley face and the color workload to get a color. It then composes the responses together and returns the smiley/color combination to the GUI for display.

• The smiley workload returns a smiley face. By default, this is a grinning smiley, U+1F603, but you can set the SMILEY environment variable to any key in the Smileys map from constants.go to get a different smiley.

• The color workload returns a color. By default, this is a light blue, but you can set the COLOR environment variable to any key in the Colors map from constants.go to get a different color, or to any arbitrary hex color code (e.g. #ff0000 for bright red).

  The named colors in the Colors map are meant to work for normal color vision and for various kinds of colorblindness, and are taken from the "Bright" color scheme shown in the "Qualitative // Color Schemes" section of https://personal.sron.nl/~pault/. For (much) more information, read the comments in pkg/faces/constants.go. Feedback here is welcome, since the Faces authors have normal color vision...