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Resolve Volume Mounts Issue in Kubernetes.md

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Problem Statement

We encountered an issue with our Nginx and PHP-FPM setup on the Kubernetes cluster this morning, which halted its functionality. Investigate and rectify the issue:

The pod name is nginx-phpfpm and the configmap name is nginx-config. Identify and fix the problem.

Once resolved, copy the /home/thor/index.php file from the jump host to the nginx-container within the nginx document root. After this, you should be able to access the website using the Website button on the top bar.

Solution

To solve the issue, we need to follow several steps to diagnose the problem and apply the necessary fixes. Below is a detailed explanation of each step along with the commands used.

1. Check the Pods

First, verify the status of the pods to ensure they are running.

kubectl get pods

Output:

NAME           READY   STATUS    RESTARTS   AGE
nginx-phpfpm   2/2     Running   0          113s

The pod nginx-phpfpm is running and both containers are ready.

2. Check the Services

Next, check the services to confirm the ports on which Nginx is listening.

kubectl get svc

Output:

NAME            TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)          AGE
kubernetes      ClusterIP   10.96.0.1      <none>        443/TCP          10m
nginx-service   NodePort    10.96.233.77   <none>        8099:30008/TCP   3m3s

The Nginx service listens on port 8099, with NodePort 30008.

3. Check ConfigMaps

Verify the configmaps to ensure the Nginx configuration is correctly loaded.

kubectl get configmaps

Output:

NAME               DATA   AGE
kube-root-ca.crt   1      12m
nginx-config       1      4m40s

Check the contents of the nginx-config configmap.

kubectl describe configmaps nginx-config

Output:

Name:         nginx-config
Namespace:    default
Labels:       <none>
Annotations:  <none>

Data
====
nginx.conf:
----
events {
}
http {
  server {
    listen 8099 default_server;
    listen [::]:8099 default_server;

    # Set nginx to serve files from the shared volume!
    root /var/www/html;
    index  index.html index.htm index.php;
    server_name _;
    location / {
      try_files $uri $uri/ =404;
    }
    location ~ \.php$ {
      include fastcgi_params;
      fastcgi_param REQUEST_METHOD $request_method;
      fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
      fastcgi_pass 127.0.0.1:9000;
    }
  }
}

BinaryData
====

Events:  <none>

The configuration in the configmap seems correct.

4. Check Pod Details

Examine the details of the nginx-phpfpm pod to identify any issues.

kubectl describe pod nginx-phpfpm

Output:

Name:             nginx-phpfpm
Namespace:        default
Priority:         0
Service Account:  default
Node:             kodekloud-control-plane/172.17.0.2
Start Time:       Sat, 03 Aug 2024 13:27:06 +0000
Labels:           app=php-app
Annotations:      <none>
Status:           Running
IP:               10.244.0.5
IPs:
  IP:  10.244.0.5
Containers:
  php-fpm-container:
    Container ID:   containerd://d5c768fd0c6836321dc937698f5932322d6770af72ccf05c012601c07fa2e53c
    Image:          php:7.2-fpm-alpine
    Image ID:       docker.io/library/php@sha256:2e2d92415f3fc552e9a62548d1235f852c864fcdc94bcf2905805d92baefc87f
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Sat, 03 Aug 2024 13:27:15 +0000
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-fgcgs (ro)
      /var/www/html from shared-files (rw)
  nginx-container:
    Container ID:   containerd://cd9e5fe44a619d726b0b05573d1f3369a49b260aaeca2d09aa5aaa50c6268f8d
    Image:          nginx:latest
    Image ID:       docker.io/library/nginx@sha256:6af79ae5de407283dcea8b00d5c37ace95441fd58a8b1d2aa1ed93f5511bb18c
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Sat, 03 Aug 2024 13:27:22 +0000
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /etc/nginx/nginx.conf from nginx-config-volume (rw,path="nginx.conf")
      /usr/share/nginx/html from shared-files (rw)
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-fgcgs (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             True 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  shared-files:
    Type:       EmptyDir (a temporary directory that shares a pod's lifetime)
    Medium:     
    SizeLimit:  <unset>
  nginx-config-volume:
    Type:      ConfigMap (a volume populated by a ConfigMap)
    Name:      nginx-config
    Optional:  false
  kube-api-access-fgcgs:
    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  2m38s  default-scheduler  Successfully assigned default/nginx-phpfpm to kodekloud-control-plane
  Normal  Pulling    2m37s  kubelet            Pulling image "php:7.2-fpm-alpine"
  Normal  Pulled     2m30s  kubelet            Successfully pulled image "php:7.2-fpm-alpine" in 7.585973665s (7.585997968s including waiting)
  Normal  Created    2m30s  kubelet            Created container php-fpm-container
  Normal  Started    2m29s  kubelet            Started container php-fpm-container
  Normal  Pulling    2m29s  kubelet            Pulling image "nginx:latest"
  Normal  Pulled     2m22s  kubelet            Successfully pulled image "nginx:latest" in 7.203594653s (7.203614392s including waiting)
  Normal  Created    2m22s  kubelet            Created container nginx-container
  Normal  Started    2m22s  kubelet            Started container nginx-container

5. Identify the Issue

The mounting path for the shared volume in the Nginx container is incorrect. It should be /var/www/html instead of /usr/share/nginx/html.

Incorrect:

/usr/share/nginx/html from shared-files (rw)

Correct:

/var/www/html from shared-files (rw)

6. Fix the Mount Path

To fix the mount path, update the Pod configuration and apply the changes.

kubectl apply -f /tmp/kubectl-edit-365337046.yaml --force

Output:

pod/nginx-phpfpm configured

7. Copy the PHP File

After fixing the issue, copy the index.php file from the jump host to the nginx-container within the Nginx document root.

kubectl cp /home/thor/index.php nginx-phpfpm:/var/www/html -c nginx-container

Verification

To verify that the issue is resolved and the website is accessible, use the Website button on the top bar. The website should now be functional, serving the PHP file correctly.

This concludes the detailed solution to investigate and rectify the Nginx and PHP