Merge pull request #49130 from network-charles/network-charles-patch-2

Improve PV Storage Task

content/en/docs/tasks/configure-pod-container/configure-persistent-volume-storage.md

@@ -191,7 +191,7 @@ Create the Pod:
 kubectl apply -f https://k8s.io/examples/pods/storage/pv-pod.yaml
 ```
 
-Verify that the container in the Pod is running;
+Verify that the container in the Pod is running:
 
 ```shell
 kubectl get pod task-pv-pod
@@ -226,10 +226,168 @@ use storage from a PersistentVolumeClaim.
 
 ## Clean up
 
-Delete the Pod, the PersistentVolumeClaim and the PersistentVolume:
+Delete the Pod:
 
 ```shell
 kubectl delete pod task-pv-pod
+```
+
+## Mounting the same PersistentVolume in two places
+
+You have understood how to create a PersistentVolume & PersistentVolumeClaim, and how to mount
+the volume to a single location in a container. Let's explore how you can mount the same PersistentVolume
+at two different locations in a container. Below is an example:
+
+{{% code_sample file="pods/storage/pv-duplicate.yaml" %}}
+
+Here:
+
+- `subPath`: This field allows specific files or directories from the mounted PersistentVolume to be exposed at
+  different locations within the container.  In this example:
+  - `subPath: html` mounts the html directory.
+  - `subPath: nginx.conf` mounts a specific file, nginx.conf.
+
+Since the first subPath is `html`, an `html` directory has to be created within `/mnt/data/`
+on the node.
+
+The second subPath `nginx.conf` means that a file within the `/mnt/data/` directory will be used. No other directory
+needs to be created.
+
+Two volume mounts will be made on your nginx container:
+
+- `/usr/share/nginx/html` for the static website
+- `/etc/nginx/nginx.conf` for the default config
+
+### Move the index.html file on your Node to a new folder
+
+The `index.html` file mentioned here refers to the one created in the "[Create an index.html file on your Node](#create-an-index-html-file-on-your-node)" section.
+
+Open a shell to the single Node in your cluster. How you open a shell depends on how you set up your cluster.
+For example, if you are using Minikube, you can open a shell to your Node by entering `minikube ssh`.
+
+Create a `/mnt/data/html` directory:
+
+```shell
+# This assumes that your Node uses "sudo" to run commands
+# as the superuser
+sudo mkdir /mnt/data/html
+```
+
+Move index.html into the directory:
+
+```shell
+# Move index.html from its current location to the html sub-directory
+sudo mv /mnt/data/index.html html
+```
+
+### Create a new nginx.conf file
+
+{{% code_sample file="pods/storage/nginx.conf" %}}
+
+This is a modified version of the default `nginx.conf` file. Here, the default `keepalive_timeout` has been
+modified to `60`
+
+Create the nginx.conf file:
+
+```shell
+cat <<EOF > /mnt/data/nginx.conf
+user  nginx;
+worker_processes  auto;
+error_log  /var/log/nginx/error.log notice;
+pid        /var/run/nginx.pid;
+
+events {
+    worker_connections  1024;
+}
+
+http {
+    include       /etc/nginx/mime.types;
+    default_type  application/octet-stream;
+
+    log_format  main  '\$remote_addr - \$remote_user [\$time_local] "\$request" '
+                      '\$status \$body_bytes_sent "\$http_referer" '
+                      '"\$http_user_agent" "\$http_x_forwarded_for"';
+
+    access_log  /var/log/nginx/access.log  main;
+
+    sendfile        on;
+    #tcp_nopush     on;
+
+    keepalive_timeout  60;
+
+    #gzip  on;
+
+    include /etc/nginx/conf.d/*.conf;
+}
+EOF
+```
+
+### Create a Pod
+
+Here we will create a pod that uses the existing persistentVolume and persistentVolumeClaim.
+However, the pod mounts only a specific file, `nginx.conf`, and directory, `html`, to the container.
+
+Create the Pod:
+
+```shell
+kubectl apply -f https://k8s.io/examples/pods/storage/pv-duplicate.yaml
+```
+
+Verify that the container in the Pod is running:
+
+```shell
+kubectl get pod test
+```
+
+Get a shell to the container running in your Pod:
+
+```shell
+kubectl exec -it test -- /bin/bash
+```
+
+In your shell, verify that nginx is serving the `index.html` file from the
+hostPath volume:
+
+```shell
+# Be sure to run these 3 commands inside the root shell that comes from
+# running "kubectl exec" in the previous step
+apt update
+apt install curl
+curl http://localhost/
+```
+
+The output shows the text that you wrote to the `index.html` file on the
+hostPath volume:
+
+```
+Hello from Kubernetes storage
+```
+
+In your shell, also verify that nginx is serving the `nginx.conf` file from the
+hostPath volume:
+
+```shell
+# Be sure to run these commands inside the root shell that comes from
+# running "kubectl exec" in the previous step
+cat /etc/nginx/nginx.conf | grep keepalive_timeout
+```
+
+The output shows the modified text that you wrote to the `nginx.conf` file on the
+hostPath volume:
+
+```
+keepalive_timeout  60;
+```
+
+If you see these messages, you have successfully configured a Pod to
+use a specific file and directory in a storage from a PersistentVolumeClaim.
+
+## Clean up
+
+Delete the Pod:
+
+```shell
+kubectl delete pod test
 kubectl delete pvc task-pv-claim
 kubectl delete pv task-pv-volume
 ```
@@ -242,21 +400,13 @@ In the shell on your Node, remove the file and directory that you created:
 ```shell
 # This assumes that your Node uses "sudo" to run commands
 # as the superuser
-sudo rm /mnt/data/index.html
+sudo rm /mnt/data/html/index.html
+sudo rm /mnt/data/nginx.conf
 sudo rmdir /mnt/data
 ```
 
 You can now close the shell to your Node.
 
-## Mounting the same persistentVolume in two places
-
-{{% code_sample file="pods/storage/pv-duplicate.yaml" %}}
-
-You can perform 2 volume mounts on your nginx container:
-
-- `/usr/share/nginx/html` for the static website
-- `/etc/nginx/nginx.conf` for the default config
-
 <!-- discussion -->
 
 ## Access control
@@ -299,4 +449,4 @@ PersistentVolume are not present on the Pod resource itself.
 * [PersistentVolume](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#persistentvolume-v1-core)
 * [PersistentVolumeSpec](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#persistentvolumespec-v1-core)
 * [PersistentVolumeClaim](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#persistentvolumeclaim-v1-core)
-* [PersistentVolumeClaimSpec](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#persistentvolumeclaimspec-v1-core)
+* [PersistentVolumeClaimSpec](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#persistentvolumeclaimspec-v1-core)

content/en/examples/pods/storage/nginx.conf

@@ -0,0 +1,31 @@
+user  nginx;
+worker_processes  auto;
+
+error_log  /var/log/nginx/error.log notice;
+pid        /var/run/nginx.pid;
+
+
+events {
+    worker_connections  1024;
+}
+
+
+http {
+    include       /etc/nginx/mime.types;
+    default_type  application/octet-stream;
+
+    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
+                      '$status $body_bytes_sent "$http_referer" '
+                      '"$http_user_agent" "$http_x_forwarded_for"';
+
+    access_log  /var/log/nginx/access.log  main;
+
+    sendfile        on;
+    #tcp_nopush     on;
+
+    keepalive_timeout  60;
+
+    #gzip  on;
+
+    include /etc/nginx/conf.d/*.conf;
+}

content/en/examples/pods/storage/pv-duplicate.yaml

@@ -19,4 +19,4 @@ spec:
   volumes:
     - name: config
       persistentVolumeClaim:
-        claimName: test-nfs-claim
+        claimName: task-pv-storage