Configurations Management with ConfigMaps and Secrets

Configmap is one of the ways to provide configurations to your application.

Injecting env variables with configmaps

Create our configmap for vote app

file: projects/instavote/dev/vote-cm.yaml

apiVersion: v1
kind: ConfigMap
  name: vote
  namespace: instavote
  OPTION_A: Visa
  OPTION_B: Mastercard

In the above given configmap, we define two environment variables,


Lets create the configmap object

kubectl get cm
kubectl apply -f vote-cm.yaml
kubectl get cm
kubectl describe cm vote

In order to use this configmap in the deployment, we need to reference it from the deployment file.

Check the deployment file for vote add for the following block.

file: vote-deploy.yaml

      - image: schoolofdevops/vote
        imagePullPolicy: Always
        name: vote
          - configMapRef:
              name: vote
        - containerPort: 80
          protocol: TCP
        restartPolicy: Always

So when you create your deployment, these configurations will be made available to your application. In this example, the values defined in the configmap (Visa and Mastercard) will override the default values(CATS and DOGS) present in your source code.

kubectl apply -f vote-deploy.yaml

Watch the monitoring screen for deployment in progress.

kubectl get deploy --show-labels
kubectl get rs --show-labels
kubectl  rollout status deploy/vote

ConfigMap Dashboard.\label{fig:captioned_image}

Note: Automatic Updation of deployments on ConfigMap Updates

Currently, updating configMap does not ensure a new rollout of a deployment. What this means is even after updading configMaps, pods will not immediately reflect the changes.

There is a feature request for this

Currently, this can be done by using immutable configMaps.

  • Create a configMaps and apply it with deployment.
  • To update, create a new configMaps and do not update the previous one. Treat it as immutable.
  • Update deployment spec to use the new version of the configMaps. This will ensure immediate update.

Enabling HTTP Authentication for Traefik with Secrets

In this part of the lab, you will

  • Create a secret with an existing file
  • Modify a ingress rule to use that secret via annotations
  • Validate if traefik, the ingress controller, automatically picks up the configurations and enables http auth s

Lets create htpasswd spec as Secret

  apt install -yq apache2-utils
  htpasswd -c auth devops

Or use Online htpasswd generator to generate a htpasswd spec. if you use the online generator, copy the contents to a file by name auth in the current directory.

Then generate the secret as,

  kubectl create secret generic mysecret --from-file auth

  kubectl get secret

  kubectl describe secret mysecret

And then add annotations to the ingress object so that it is read by the ingress controller to update configurations.

file: vote-ing.yaml

apiVersion: extensions/v1beta1
kind: Ingress
  name: vote
  annotations: traefik "basic" "mysecret"
    - host:
          - path: /
              serviceName: vote
              servicePort: 82
    - host:
          - path: /
              serviceName: results
              servicePort: 81


  • "basic" defines authentication type that needs to be added.
  • "mysecret" refers to the secret created earlier.


kubectl apply -f vote-ing.yaml
kubectl get ing/vote -o yaml

Observe the annotations field. No sooner than you apply this spec, ingress controller reads the event and a basic http authentication is set with the secret you added.

       +--update----> | traefik  |
       |              |  configs |
       |              +----------+
  +----+----+--+            ^
  | ingress    |            :
  | controller |            :
  +----+-------+            :
       |              +-----+-------+
       +---watch----> | ingress     | <------- user
                      | annotations |

Name Based Routing