Kubernetes Classroom Series – 13/Jul/2021

Ambassador

  • Overview: This pattern is a specialized sidecar repsonsible for hiding the complexity and providing the unified interface for accessing the services
  • To demonstrate this pattern, lets say we use a cache for application. In the local developer environment we want tous memcached and in production we want to use etcd.
  • So we create an Ambassador container which accesses the memcached and also the ambassador container which uses local memcached
  • Depending on the envoronment we can use the Ambassador container. Preview Preview
  • Refer Here for the sample created

Configuration Patterns

  • Every application needs to be configured and easy way to do it by storing configurations in code. This approach has side effect of configuration and code living and dying together.
  • We still need the flexibility to adapt configuration without recreating application image.

EnvVar Conifiguration

  • Refer Here for the config Map
  • Use environmental variables is easier way to setup configuration for simple use cases
  • Environmental variables are set only before the application starts and we cannot change them later
  • Refer Here for the manifests

Configuration Resource

  • One significant disadvantage of the EnvVar Configuration pattern is that it’s suitable for only a handful of variables and simple configurations.
  • Often its better to keep all the configuration data in a single place.
  • kuberenetes has dedicated Configuration Resources that are more flexible than pure environment variables
  • These are ConfigMap and Secret Objects for general-purpose configuration and sensitive data respectively
  • Once a config Map is create and holding data, we can use the keys of Config Maps in two ways
    • As a reference for environmental variables. Key is environmental variable
    • As files that are maaped to a volume mounted in a Pod. Key is file name
  • The file mounted ConfigMap Volume is updated when the ConfigMap is update via k8s api.
  • Refer Here for the configmap as volume mount.

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