ConfigME

A Kubernetes operator to load the configmap data from different datasources. There are situations where services in a Kubernetes cluster may need data provided by different datasources like HTTP-API, files in a GitServer or kafka topic to name a few.

If the data is cacheable, mapping them to a ConfigMap would contribute to the resiliency of the service as it wouldn't be dependent to the availability of the other service.

Alternatives:

caching the data in every pod

Not to mention that while the external service is down your service can't scale or the pods being respawned.

A central Cache like Redis, Memcached

Well, this solution is already better than the previous one... but really? you want to spend your resoures to implement a thing identical to what K8s already provides?

How to install the operator

The simplest way to install the Configme on your K8s cluster is running the following command:

⚠ WARNING: it will create a new namespace called configme-operator and deploy the operator in it. If it is not desirable, consider to edit the file according to your requirements.

kubectl apply -f https://raw.githubusercontent.com/psycho-ir/configme/master/crd/ConfigSource.yml
kubectl apply -f https://raw.githubusercontent.com/psycho-ir/configme/master/deployment/operator.yml 

How to define ConfigSource

Configme introduces a new Custom Resource Definition in your cluster called ConfigSource.

A ConfigSource defining a mapping from a http endpoint to a Configmap in your cluster will look like this:

apiVersion: configme.javaworm.com/v1beta1
kind: ConfigSource
metadata:
  name: simple-http-configsource
  namespace: test-configme
spec:
  sourceType: http
  targetConfigMapName: todos-config
  sourceConfig: 
    url: https://jsonplaceholder.typicode.com/todos
    intervalSeconds: 10

The example above will call the url https://jsonplaceholder.typicode.com/todos every 10 seconds and update the ConfigMap called todos-config in namespace test-configme.

What if the endpoint is secured

It is quite simple to load the configuration from a secured http endpoint.

Configme currently supports bearer tokens loaded from a secret living in the same namespace as ConfgiSource itself is living.
If you are interested in any other authentication method, feel free to open an issue (you are very welcomed to contribute to the code as well!)

The following example shows how to do setup bearer authentication method:

apiVersion: configme.javaworm.com/v1beta1
kind: ConfigSource
metadata:
  name: bearer-http-configsource
  namespace: test-configme
spec:
  sourceType: http
  targetConfigMapName: bearer-http-config
  sourceConfig:
    url: https://jsonplaceholder.typicode.com/todos
    intervalSeconds: 5
    authenticationMethod: bearer
    authenticationConfig:
      tokenType: Bearer
      secretName: source-credentials
      tokenSecretKey: default-token-secret

Load config files from Github repositories

Given that Github has the possibility to provide the files in raw format, it's quite easy to fetch the load configs from Github through sourceType: http.

The example below shows how to load the configuration from master branch of a private repository:

apiVersion: v1
data:
  token: base64(GITHUB_TOKEN)
kind: Secret
metadata:
  name: github-credentials
type: Opaque
---

apiVersion: configme.javaworm.com/v1beta1
kind: ConfigSource
metadata:
  name: bearer-http-configsource
spec:
  sourceType: http
  targetConfigMapName: readme-config
  sourceConfig:
    url: https://raw.githubusercontent.com/psycho-ir/private-repository/master/config.json
    intervalSeconds: 5
    authenticationMethod: bearer
    authenticationConfig:
      tokenType: Bearer
      secretName: github-credentials
      tokenSecretKey: token

TODO

• Handle http errors may happen
• Native image build
• Docker Image
• Different Authentications methods
  • none
  • bearer
  • basic
  • api-key
  • ...
• How to use document
• Provide configs as is and Gzip
• Schema support for fetched configuration