Step 1: The sample application and git repository
Sample Ruby application
The sample application used in this tutorial is based on Sinatra and prints out environment variables.
Even though it’s a minimal application it will serve well to describe the basic concepts. You do not have to use our sample application, but for the first steps it might be helpful.
Git repository hosting
To create new application you need to have your source code hosted somewhere on the internet and have it accessible using git. Popular choices are GitHub, GitLab or BitBucket. For example, our sample application is hosted at Github. For this tutorial you may use the code from the provided repository or you can fork the repository. Forking is necessary if you want to follow also through
Step 2: Creating new application
Creating new application using terminal
Once ready, open a terminal and at the command prompt, enter the following command to create a Ruby application (replace the username in the URL if you have forked, or the whole URL if you are using your own application):
<code>oc new-app --name=myapp ruby~https://github.com/OpenShiftDemos/os-sample-ruby.git</code>
And the output should look something like this:
--> Found image d5ca607 (5 weeks old) in image stream "ruby" in project "openshift" under tag "2.2" for "ruby"
Platform for building and running Ruby 2.2 applications
Tags: builder, ruby, ruby22
* A source build using source code from https://github.com/OpenShiftDemos/os-sample-ruby.git will be created
* The resulting image will be pushed to image stream "myapp:latest"
* This image will be deployed in deployment config "myapp"
* Port 8080/tcp will be load balanced by service "myapp"
* Other containers can access this service through the hostname "myapp"
--> Creating resources with label app=myapp ...
imagestream "myapp" created
buildconfig "myapp" created
deploymentconfig "myapp" created
service "myapp" created
Build scheduled, use 'oc logs -f bc/myapp' to track its progress.
Run 'oc status' to view your app.
--name=myapp names the application. By default it would be the base name of the URL without extension, in our case
os-sample-ruby, but it’s much nicer to have the application named
myapp and that’s what we did using this switch.
OpenShift automatically linked ruby with
Ruby 2.2 as the latest version. You could as well use
ruby20 as the template to deploy using the specific version, e.g.
<code>oc new-app --name=myapp ruby20~https://github.com/OpenShiftDemos/os-sample-ruby.git</code>
OpenShift prints a lot of information that is not that important for us at this moment, what we care about is if our application is accessible from the internet and if we can see it running. For exposing application to the outside world, OpenShift has a concept of
routes that map domain names to specific applications.
To expose our application we need to know the name of the internal service in all the information printed when we created our application it’s this line
service "myapp" created.
OpenShift automatically created new service, according to the name of the application. Now, let’s expose that service, to do that, run this command:
<code>oc expose svc myapp</code>
And you should see something like this:
<code>route "myapp" exposed</code>
Now we can run
oc status to get information about your deployment
and you should see something like this
http://myapp-demo.44fs.preview.openshiftapps.com to pod port 8080-tcp (svc/myapp)
dc/myapp deploys istag/myapp:latest <-
bc/myapp builds https://github.com/OpenShiftDemos/os-sample-ruby.git with openshift/ruby:2.2
deployment #1 deployed 41 seconds ago - 1 pod
There again is a lot of information that we mostly do not care about at this moment but what we need is the first line. It shows you the domain, your application is available at. To access the application, simply open the domain in your browser of choice and you should see the environment variables.
Creating new application using web console
You can deploy your application using web console as well as wit cli tools. To deploy using web, click on the
Add to project in the top bar. Then type
ruby into the Filter by keyword text field. And you will see list of Ruby based templates similar to:
ruby:latestand fill in the form like this:
Createand you will be taken to summary page like this:
Continue to overview. On the overview page you will see detail of your new deployment similar to:
Clicking the URL in the top white box will take you straight to your newly deployed application with the environment variables.
Step 3: Making first changes
To make changes to the application, you need to fork it and deploy from your own fork instead of from the original repository of the sample application. That means, that for creating the application the URL will have a different username/organization.
<code>oc new-app --name=myapp ruby~https://github.com/[your user name]/os-sample-ruby.git</code>
Except for that, the whole process process in the Step 1 is the same.
Editing the source code
You can edit the source code in Github’s web based editor. If you choose to do so, there no need to copy the source code to your local machine and can skip directly to Step 2.2.
Or you can clone the repository locally, edit the file, and push back to the server. To do so, first clone the git repository and enter the new directory
git clone https://github.com/[your user name]/os-sample-ruby.git
config.ru file to your liking and commit the changes
git add -A .
git commit -m "My application changes"
<code>git push origin master</code>
and that’s it, the change is in the git repository, now let’s go and deploy it.
Deploying the changes using terminal
OpenShift already knows how to reach your git repository as it did while first deploying the application. As it created the service that we referenced before it also created buildconfig
buildconfig "myapp" created.
BuildConfigs contain information necessary for building an application. It also contain information what strategy should be used for building it. In our case the strategy is
Source. For strategy from source it contains the URL of git repository to fetch the source code from and other important stuff. you can check more details by running
oc describe bc myapp.
BuildConfig is the reference for building stuff and allows us to trigger the building process, to do this run
<code>oc start-build myapp</code>
And you should see something like this:
Once the build finishes, refresh your browser with the application and you shall see the changes you just made.
Deploying the changes using web console
The web UI allows you to trigger builds as well. In the web console go to
Browser → Builds and there you will see a line similar to
myappand on the next page click the
Start Buildbutton in the top right corner.
Overviewin the main left navigation panel. You will be taken back to the overview page, where you will see that you build is running:
You can again click your application URL and see the changes.