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
• COW_COLOR: what color the cow 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

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

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.