Rancher/Kubernetes Demo Application

This is a Go demo application used for demonstrating Kubernetes and load balancing.

It will create a colored icon for each replica within a ReplicaSet and indicate which one most recently served a response. Replicas which haven't been heard from will begin to fade out, until after a configurable number of seconds they will disappear. This is useful for demonstrating scaling up/down or in the case of an application like Rio, for showing scale-in of an upgraded application.

Environment Variables

• TITLE: sets title in demo app
• SHOW_VERSION: show version of app in ui (VERSION env var)
• REFRESH_INTERVAL: interval in milliseconds for page to refresh (default: 1000)
• EXPIRE_INTERVAL: how long a replica can go without being seen before we remove it from the display (default: 10s)
• REMOVE_INTERVAL: how long after EXPIRE_INTERVAL until we remove the icon (default: 20s)
• SKIP_ERRORS: set this to prevent errors from counting (useful on janky load balancers)
• METADATA: extra text at bottom of info area
• CONTAINER_COLOR: what color the container background should be (default: black). Valid options are any color from the CSS pallete, including:
  • red
  • orange
  • yellow
  • olive
  • green
  • teal
  • blue
  • violet
  • purple
  • pink
  • black
• PETS: The kind of pet shown in each container. Valid options are:
  • cows
  • chameleons
  • cowmeleons

Build

docker build -t monachus/rancher-demo .

Paths

By default the loaded page will reach back to /demo every REFRESH_INTERVAL and use the returned information to update the display. Other paths are:

• /info - returns some additional information about the replica serving the request
• /load - adds a 2s delay to the response from /info - use this for putting artificial load on the system and watching the replicas scale

Ports

The container will listen for traffic on port 8080.

Running

Deploy using the included Helm chart under ./charts or alternatively:

1. Edit base/configs/source-vars.yaml and set the following:
   • MY_NAMESPACE: the namespace into which the app will be deployed (default: rancher-demo). This will be created if it does not already exist.
   • URL_HOST: the hostname portion of the URL that the ingress will answer on (default: rancher-demo.cl.monach.us)
2. Run kubectl apply -k base to deploy the application.