Injecting configurations from key/value literals

Hopefully, even when our applications need different configs to work in distinct clusters, the differences are limited. Often, they should be limited to only a few key/value entries. In such cases, it might be easier to create ConfigMaps using --from-literal.

Let's take a look at an example:

kubectl create cm my-config \
    --from-literal=something=else \
    --from-literal=weather=sunny
    
kubectl get cm my-config -o yaml  

The output of the latter command is as follows (metadata is removed for brevity):

apiVersion: v1 
data: 
  something: else 
  weather: sunny 
kind: ConfigMap 
... 

We can see that two entries were added, one for each literal.

Let's create a Pod with the ConfigMap mounted:

kubectl create -f cm/alpine.yml 
 
kubectl exec -it alpine -- \
    ls /etc/config 

The output of the latter command is as follows...