Configuration Resource

For trying out this example you need to have access to a Kubernetes cluster, e.g. by choosing one of the options from INSTALL.

Our sample [random-generator] REST service can be configured with environment variables and an application.properties configuration file. We will now provide this configuration via a ConfigMap.

For this, let’s create the ConfigMap with:

kubectl create -f https://k8spatterns.io/ConfigurationResource/configmap.yml

The following Pod declaration will now put up this ConfigMap for being used as environment variables and mounted as files in a directory /config.

Please check out the comments in pod.yml which provide some more explanations.

Let’s create that Pod with:

kubectl create -f https://k8spatterns.io/ConfigurationResource/pod.yml

Like in the other examples we expose a nodePort service for accessing our service:

kubectl create -f https://k8spatterns.io/ConfigurationResource/service.yml

Now let’s access the service where we again assume that your cluster node’s have an external IP address which can be directly contacted from your desktop.

The /info endpoint will return the configuration data that has been picked up by the random-generator Pod:

port=$(kubectl get svc random-generator -o jsonpath={.spec.ports[0].nodePort})
# Use Minikube's IP or any external accessible node IP from your cluster
ip=$(minikube ip)
curl -s http://$ip:$port/info | jq .

In order to filter on the environment variables which have been bulk-exposed with a CONFIG_ prefix in an envFrom section, use:

# Check also for env variables which has been set via envFrom
curl -s http://$ip:$port/info | \
   jq '.env | with_entries(select(.key | startswith("CONFIG_")))'

More Information

• Configuration Resource example

• ConfigMap Documentation

• Secrets Documentation

• gitRepo Volumes

• Size restriction of a ConfigMap