Challenge - ConfigMap
- Docker & Kubernetes course
- Intermediate
- Lesson 81/82
- 5 min
Write a ConfigMap and mount it as env in a Pod.
Challenge: externalize the config
Instead of baking an nginx site's config file into the image, you'll move it into a ConfigMap. The file will be mounted as a volume; when the config changes, the file will update without restarting the pods, and nginx will be told to reload.
kubectl create configmap nginx-ayar --from-file=default.conf
# ... volumes: configMap: nginx-ayar -> /etc/nginx/conf.d
kubectl create configmap nginx-ayar --from-file=default.conf --dry-run=client -o yaml | kubectl apply -f -
kubectl exec deploy/web -- nginx -s reloadPractice A deployment template with a volume
Write a Deployment template's spec section (starting with spec:): an ayar volume from the nginx-ayar ConfigMap under volumes; container named nginx, image nginx:1.27; mount ayar at /etc/nginx/conf.d with readOnly: true.
Starter code
# buraya yazSample solution
spec:
volumes:
- name: ayar
configMap:
name: nginx-ayar
containers:
- name: nginx
image: nginx:1.27
volumeMounts:
- name: ayar
mountPath: /etc/nginx/conf.d
readOnly: trueExpected output
deployment.apps/web configured
Practice Update the config
Write three commands: generate the nginx-ayar ConfigMap from the default.conf file as YAML without creating it and pipe it into kubectl apply -f -; check the file by running cat /etc/nginx/conf.d/default.conf in deploy/web; run nginx -s reload in deploy/web.
Starter code
# buraya yazSample solution
kubectl create configmap nginx-ayar --from-file=default.conf --dry-run=client -o yaml | kubectl apply -f -
kubectl exec deploy/web -- cat /etc/nginx/conf.d/default.conf
kubectl exec deploy/web -- nginx -s reloadExpected output
configmap/nginx-ayar configured
server {
listen 80;
location / { root /usr/share/nginx/html; }
}
2026/11/03 13:05:21 [notice] 42#42: signal process started
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 In this setup, what would happen if the config file were mounted with subPath?
- There'd be no difference
- The ConfigMap update wouldn't reach the file Correct answer
- The file would never appear
- nginx would crash
Explanation: subPath mounts aren't refreshed automatically.
2 Make nginx reload its config.
kubectl exec deploy/web -- nginx -s ____kubectl exec deploy/web -- nginx -s reloadExplanation: nginx -s reload rereads the config without stopping the process.
3 Match.
| Term | Meaning |
|---|---|
--from-file=default.conf |
ConfigMap from a file |
configMap volume |
Mount as a file |
| kubectl apply -f - |
Update |
nginx -s reload |
Reload |