Summary:
This example only uses the hosts local storage and will familiarize users with some basic concepts of pod/container configuration files and OSE operations. The goal for this task is to successfully deploy a simple nginx pod, map the nginx containers html root directory to a directory on the Atomic Host where html files can be served. This means when the pod/container is destroyed, the html files will still be available on the Atomic host. Lastly, to view the running pod from within the OSE Console Web Interface.
- Let’s first set up a simple nginx application that will utilize the local host storage for the web server pages. This example uses the
local-nginx-pod.json, Here is the pod configuration file. Below is a brief explanation of some of the attributes and values used in the file.
local-nginx-pod.json
{
"apiVersion": "v1",
"id": "local-nginx",
"kind": "Pod",
"metadata": {
"name": "local-nginx"
},
"spec": {
"containers": [
{
"name": "local-nginx",
"image": "fedora/nginx",
"volumeMounts": [
{
"mountPath": "/usr/share/nginx/html/test",
"name": "localvol"
}
]
}
],
"volumes": [
{
"name": "localvol",
"hostPath": {
"path": "/opt/data"
}
}
]
}
}
Under volumeMounts
mountPath: /usr/share/nginx/html/testlocal This is the local container mount and storage path (so from container, this path will be created)
name: localvol This is the name of our mount volume and it should match any volumes listed below in the volume section
Under volumes
name: localvol matches name: localvol from volumeMounts
hostPath hostPath means local storage on the host, so we have a directory /opt/data local on our host (it must exist)
path: /opt/data This is the host mounted path, so you can update or change files from here, like the hello.html or other web pages to be served
`
-
Use the OpenShift Console (oc) to deploy the pod
oc create -f local-nginx-pod.json [root@ose1 nginx_local]# oc create -f local-nginx-pod.json pods/local-nginx -
After a few minutes (this may vary), check and make sure the pod is running
oc get pods [root@ose1 nginx_local]# oc get pods NAME READY STATUS RESTARTS AGE local-nginx 1/1 Running 0 15m -
You should now also see the pod running in your OSE Console web Interface (https://:8443/console) (if AllowAll was enabled, should just be able to login with any id and password)
-
From the OSE Console, Note the “IP on node” and “Node” values, which will tell you what ip and node the nginx application is running on.
-
Create a sample (helloworld.html) html page to serve out of the Atomic host
/opt/datadirectory. This is the location of our local mount defined by the mountPath from thelocal-nginx-pod.json. SSH to the node where the nginx application is running and create the helloworld.html file in the /opt/data directory.ssh root@<Atomic Node> echo “Hello World! This is being served from local Atomic Host – in /opt/data” >> /opt/data/helloworld.html -
ssh into the node using the container_id obtained from “docker ps” command and notice if you go to the nginx root /usr/share/nginx/html/test, you will see the helloworld.html file that we created on our atomic host from the mapped /opt/data directory
docker ps [root@ose2 data]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 7f27314f5c3e fedora/nginx "/usr/sbin/nginx" 24 minutes ago Up 24 minutes k8s_local-nginx.ce2651ae_local-nginx_default_d7747b33-45ce-11e5-ae70-52540008f001_3b81240d e3b931561c07 openshift3/ose-pod:v3.0.1.0 "/pod" 27 minutes ago Up 27 minutes k8s_POD.892ec37e_local-nginx_default_d7747b33-45ce-11e5-ae70-52540008f001_ff8363f0 docker exec -it 7f27314f5c3e bash [root@ose2 data]# docker exec -it 7f27314f5c3e bash bash-4.3# cd /usr/share/nginx/html/testlocal/ bash-4.3# ls hello.html *helloworld.html* -
Enter simple curl command from the docker container to serve the page
curl http://10.1.0.2/testlocal/helloworld.html bash-4.3# curl http://10.1.0.2/testlocal/helloworld.html “Hello World! This is being served from local Atomic Host – in /opt/data”
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