Lab Information
There are a number of parameters that are used by the applications. We need to define these as environment variables, so that we can use them as needed within different configs. Below is a scenario which needs to be configured on Kubernetes cluster. Please find below more details about the same.
Create a pod named envars.
Container name should be fieldref-container, use image busybox preferable latest tag, use command 'sh', '-c' and args should be
'while true; do
echo -en '/n';
printenv NODE_NAME POD_NAME;
printenv POD_IP POD_SERVICE_ACCOUNT;
sleep 10;
done;'
(Note: please take care of indentations)
Define Four environment variables as mentioned below:
a.) The first env should be named as NODE_NAME, set valueFrom fieldref and fieldPath should be spec.nodeName.
b.) The second env should be named as POD_NAME, set valueFrom fieldref and fieldPath should be metadata.name.
c.) The third env should be named as POD_IP, set valueFrom fieldref and fieldPath should be status.podIP.
d.) The fourth env should be named as POD_SERVICE_ACCOUNT, set valueFrom fieldref and fieldPath shoulbe be spec.serviceAccountName.
Set restart policy to Never.
To check the output, exec into the pod and use printenv command.
Note: The kubectl utility on jump_host has been configured to work with the kubernetes cluster.
Lab Solutions
Step 1: Create the Pod Configuration
Create a file named envars-pod.yaml:
apiVersion: v1
kind: Pod
metadata:
name: envars
spec:
containers:
- name: fieldref-container
image: busybox:latest
command:
- 'sh'
- '-c'
args:
- |
while true; do
echo -en '\n';
printenv NODE_NAME POD_NAME;
printenv POD_IP POD_SERVICE_ACCOUNT;
sleep 10;
done;
env:
- name: NODE_NAME
valueFrom:
fieldRef:
fieldPath: spec.nodeName
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
- name: POD_IP
valueFrom:
fieldRef:
fieldPath: status.podIP
- name: POD_SERVICE_ACCOUNT
valueFrom:
fieldRef:
fieldPath: spec.serviceAccountName
restartPolicy: Never
Step 2: Apply the Pod Configuration
Deploy the pod to the Kubernetes cluster:
kubectl apply -f envars-pod.yaml
Step 3: Verify the Pod is Running
Check the pod status:
kubectl get pods
Step 4: Check the Pod Logs
Since the container is running a continuous loop that prints environment variables, you can check the logs to see the output:
kubectl logs envars
Step 5: Exec into the Pod and Verify Environment Variables
Execute into the pod to manually check the environment variables:
kubectl exec -it envars -- /bin/sh
#Once inside the container, run:
printenv
#Exit the container:
exit
Step 6: Detailed Verification
Let's verify all components are correctly configured:
Check pod details:
kubectl describe pod envars
Output
thor@jumphost ~$ kubectl describe pod envars
Name: envars
Namespace: default
Priority: 0
Service Account: default
Node: kodekloud-control-plane/172.17.0.2
Start Time: Tue, 04 Nov 2025 10:37:43 +0000
Labels: <none>
Annotations: <none>
Status: Running
IP: 10.244.0.5
IPs:
IP: 10.244.0.5
Containers:
fieldref-container:
Container ID: containerd://5c07316533aab139456369be9719d5d5bf8b25850aa7123700ee6e0af29277d4
Image: busybox:latest
Image ID: docker.io/library/busybox@sha256:e3652a00a2fabd16ce889f0aa32c38eec347b997e73bd09e69c962ec7f8732ee
Port: <none>
Host Port: <none>
Command:
sh
-c
Args:
while true; do
echo -en '\n';
printenv NODE_NAME POD_NAME;
printenv POD_IP POD_SERVICE_ACCOUNT;
sleep 10;
done;
State: Running
Started: Tue, 04 Nov 2025 10:37:44 +0000
Ready: True
Restart Count: 0
Environment:
NODE_NAME: (v1:spec.nodeName)
POD_NAME: envars (v1:metadata.name)
POD_IP: (v1:status.podIP)
POD_SERVICE_ACCOUNT: (v1:spec.serviceAccountName)
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-mvs4m (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
kube-api-access-mvs4m:
Type: Projected (a volume that contains injected data from multiple sources)
TokenExpirationSeconds: 3607
ConfigMapName: kube-root-ca.crt
ConfigMapOptional: <nil>
DownwardAPI: true
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 3m20s default-scheduler Successfully assigned default/envars to kodekloud-control-plane
Normal Pulling 3m19s kubelet Pulling image "busybox:latest"
Normal Pulled 3m19s kubelet Successfully pulled image "busybox:latest" in 315.653926ms (315.66919ms including waiting)
Normal Created 3m19s kubelet Created container fieldref-container
Normal Started 3m19s kubelet Started container fieldref-container
Check the environment variables in the pod spec:
kubectl get pod envars -o yaml | grep -A 20 "env:"
Step 7: Understanding the Field References
The environment variables are set using Downward API field references:
NODE_NAME: spec.nodeName - Gets the name of the node where the pod is running
POD_NAME: metadata.name - Gets the name of the pod (envars)
POD_IP: status.podIP - Gets the IP address assigned to the pod
POD_SERVICE_ACCOUNT: spec.serviceAccountName - Gets the service account name (defaults to default)
Step 8: Continuous Monitoring
To watch the logs in real-time:
kubectl logs envars -f
Press Ctrl+C to exit the log view.
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