11.4. Deploying your application to OpenShift Container Platform
You can deploy you application to OpenShift Container Platform.
After creating the rails-app project, you are automatically switched to the new project namespace.
Deploying your application in OpenShift Container Platform involves three steps:
- Creating a database service from OpenShift Container Platform’s PostgreSQL image.
- Creating a frontend service from OpenShift Container Platform’s Ruby 2.0 builder image and your Ruby on Rails source code, which are wired with the database service.
- Creating a route for your application.
Procedure
To deploy your Ruby on Rails application, create a new project for the application:
$ oc new-project rails-app --description="My Rails application" --display-name="Rails Application"
11.4.1. Creating the database service
Your Rails application expects a running database service. For this service use PostgeSQL database image.
To create the database service, use the oc new-app command. To this command you must pass some necessary environment variables which are used inside the database container. These environment variables are required to set the username, password, and name of the database. You can change the values of these environment variables to anything you would like. The variables are as follows:
- POSTGRESQL_DATABASE
- POSTGRESQL_USER
- POSTGRESQL_PASSWORD
Setting these variables ensures:
- A database exists with the specified name.
- A user exists with the specified name.
- The user can access the specified database with the specified password.
Procedure
Create the database service:
$ oc new-app postgresql -e POSTGRESQL_DATABASE=db_name -e POSTGRESQL_USER=username -e POSTGRESQL_PASSWORD=password
To also set the password for the database administrator, append to the previous command with:
-e POSTGRESQL_ADMIN_PASSWORD=admin_pw
Watch the progress:
$ oc get pods --watch
11.4.2. Creating the frontend service
To bring your application to OpenShift Container Platform, you must specify a repository in which your application lives.
Procedure
Create the frontend service and specify database related environment variables that were setup when creating the database service:
$ oc new-app path/to/source/code --name=rails-app -e POSTGRESQL_USER=username -e POSTGRESQL_PASSWORD=password -e POSTGRESQL_DATABASE=db_name -e DATABASE_SERVICE_NAME=postgresql
With this command, OpenShift Container Platform fetches the source code, sets up the builder builds your application image, and deploys the newly created image together with the specified environment variables. The application is named
rails-app.Verify the environment variables have been added by viewing the JSON document of the
rails-appdeployment config:$ oc get dc rails-app -o json
You should see the following section:
- Example output
env": [
{
"name": "POSTGRESQL_USER",
"value": "username"
},
{
"name": "POSTGRESQL_PASSWORD",
"value": "password"
},
{
"name": "POSTGRESQL_DATABASE",
"value": "db_name"
},
{
"name": "DATABASE_SERVICE_NAME",
"value": "postgresql"
}
],Check the build process:
$ oc logs -f build/rails-app-1
Once the build is complete, look at the running pods in OpenShift Container Platform:
$ oc get pods
You should see a line starting with
myapp-<number>-<hash>, and that is your application running in OpenShift Container Platform.Before your application is functional, you must initialize the database by running the database migration script. There are two ways you can do this:
Manually from the running frontend container:
Exec into frontend container with
rshcommand:$ oc rsh <frontend_pod_id>
Run the migration from inside the container:
$ RAILS_ENV=production bundle exec rake db:migrate
If you are running your Rails application in a
developmentortestenvironment you do not have to specify theRAILS_ENVenvironment variable.
- By adding pre-deployment lifecycle hooks in your template.
11.4.3. Creating a route for your application
You can expose a service to create a route for your application.
Procedure
To expose a service by giving it an externally-reachable hostname like
www.example.comuse OpenShift Container Platform route. In your case you need to expose the frontend service by typing:$ oc expose service rails-app --hostname=www.example.com
Ensure the hostname you specify resolves into the IP address of the router.
