Openshift quickstart: Django

This is a Django project that you can use as the starting point to develop your own and deploy it on an OpenShift cluster.

The steps in this document assume that you have access to an OpenShift cluster that you can deploy applications on. Instructions for University of Michigan employees can be found here: https://tinyurl.com/y9gmudj6

What has been done for you

This is a minimal Django 1.11 project.

Local development

To run this project in your development machine, follow these steps:

Fork this repo and clone your fork:

git clone https://github.com/chriskretler/django-ex.git
Build the docker image:

docker build -t django-ex .
Run the docker image:

docker run -it -p 8000:8000 django-ex
Open your browser and go to http://127.0.0.1:8000, you will be greeted with a welcome page.

Deploying to OpenShift

To follow the next steps, you need to be logged in to an OpenShift cluster and have an OpenShift project where you can work on.

You can use the oc command like to create your application:

oc new-app <your repository location>

Your application will be built and deployed automatically. If that doesn't happen, you can debug your build:

oc get builds
# take build name from the command above
oc logs build/<build-name>

And you can see information about your deployment too:

oc describe dc/django-example

In the web console, the overview tab shows you a service, by default called "django-example", that encapsulates all pods running your Django application. You can access your application by browsing to the service's IP address and port. You can determine these by running

oc get svc

Logs

By default your Django application is served with gunicorn and configured to output its access log to stderr. You can look at the combined stdout and stderr of a given pod with this command:

oc get pods         # list all pods in your project
oc logs <pod-name>

This can be useful to observe the correct functioning of your application.

Special environment variables

One-off command execution

At times you might want to manually execute some command in the context of a running application in OpenShift. You can drop into a Python shell for debugging, create a new user for the Django Admin interface, or perform any other task.

You can do all that by using regular CLI commands from OpenShift. To make it a little more convenient, you can use the script openshift/scripts/run-in-container.sh that wraps some calls to oc. In the future, the oc CLI tool might incorporate changes that make this script obsolete.

Here is how you would run a command in a pod specified by label:

Inspect the output of the command below to find the name of a pod that matches a given label:
```
 oc get pods -l <your-label-selector>
```
Open a shell in the pod of your choice. Because of how the images produced with CentOS and RHEL work currently, we need to wrap commands with bash to enable any Software Collections that may be used (done automatically inside every bash shell).
```
 oc exec -p <pod-name> -it -- bash
```
Finally, execute any command that you need and exit the shell.