Krazy Cow

           (    )
            (oo)
   )\.-----/(O O)
  # ;       / u
    (  .   |} )
     |/ ".;|/;
     "     " "

This is Krazy Cow - a Kubernetes friendly animal that it also moody and requires special attention. It helps you learn how containers and whole Cloud Native system can work together to bring more speed to your environments.

It also fun to play with!

Features

Configuration provided by yaml file (with all defaults placed in config/defaultconfig.yaml) and environment variables
Plain http and additional, optional https endpoint - key and certificate files required
Logging with colored output and different, configurable severity levels (see https://github.com/op/go-logging)
Healthcheck endpoint that returns error when cow mood is below a defined threshold
Artificial "mood changer" can be attached to a cow to decrease the mood every N seconds
Logging all requests (access logs)
Different output for text (curl,wget) and browser clients
"Shepherd" (redis) can be a destination for access logs
When "pasture" location is provided to a cow with tufts (files tuft*) then it is being periodically eaten by a cow increasing its mood AND producing a milk; if a shepherd is available then it is sent to a dairy (a key with that name in redis); when there are no tufts left in pasture a cow mood is decreased
Cow can be set free using /setfree endpoint. Optionally it can be secured with basic http authentication.
Two custom metrics are available at /metrics endpoint:
- cow_requests with request count
- cow_mood with current mood of a cow

Endpoints

/ - talk with a cow
/metrics - standard Prometheus endpoint
/setfree - set free a cow (cause a process to exit(1))
/healthz - healthcheck; also display current mood of the cow

Configuration

Configuration is handled by viper (https://github.com/spf13/viper) and thus yaml files and environment variables can be used.

With a config file

Create cowconfig.yaml and put it in the same directory as the app (binary file) or in the /config/ directory. The latter location is used when running a container with a config file mounted from ConfigMap.

With environment variable

Start a cow with environment variable set with the following scheme:

For the following variable

cow:
  say: "Moo"

override with KC_COW_SAY="Hello"

TLS

By default tls is disabled. To enable make sure your config the following entries:

http:
    port: 8080 # <-- this is default port
    tls:
        enabled: true
        cert: config/server.crt # <-- path to a cert file
        key: config/server.key # <-- path to a key file

Authentication

Currently only /setfree is protected with http basic authentication. To set it up you need to point a credentials file with http.auth.credentials variable and enable it with http.auth.enabled set to true.

Credentials must be put in a file in this very simple format: USERNAME:PASSWORD.

Access Kubernetes API

To enable access to Kubernetes api and enable features of herd discovery a rolebinding is required. To create it simply add it with a command:

kubectl create clusterrolebinding cowview --clusterrole=view --serviceaccount=default:default

cloudowski / krazy-cow