- Node.js sample app on OpenShift!
This example will serve a welcome page and the current hit count as stored in a database.
There are four methods to get started with OpenShift v3:
- Running a virtual machine with Vagrant
- Running a virtual machine managed by minishift
- Starting a Docker container
- Downloading the binary
- Running an Ansible playbook
One option is to use the Vagrant all-in-one launch as described in the OpenShift Origin All-In-One Virtual Machine. This option works on Mac, Windows and Linux, but requires that you install Vagrant running VirtualBox.
Another option to run virtual machine but not having to using Vagrant is to download and use the minishift binary as described in its getting started section. minishift can be used to spin up a VM on any of Windows, Linux or Mac with the help of supported underlying virtualization technologies like KVM, xhyve, Hyper-V, VirtualBox.
Another option is running the OpenShift Origin Docker container image from Docker Hub launch as described in the Getting Started for Administrators. This method is supported on Fedora, CentOS, and Red Hat Enterprise Linux (RHEL) hosts only.
Red Hat periodically publishes OpenShift Origin Server binaries for Linux, which you can download on the OpenShift Origin GitHub Release page. Instructions on how to install and launch the Openshift Origin Server from binary are described in Getting Started for Administrators.
Outlined as the Advanced Installation method for poduction environments, OpenShift Origin is also installable via Ansible playbook made avaialble on the GitHub openshift-ansible repo.
After logging in with oc login (default username/password: openshift), if you don't have a project setup all ready, go ahead and take care of that:
$ oc new-project nodejs-echo \
--display-name="nodejs" --description="Sample Node.js app"
That's it, project has been created. Though it would probably be good to set your current project to this (thought new-project does it automatically as well), such as:
$ oc project nodejs-echo
You can create a new OpenShift application using the web console or by running the oc new-app command from the CLI. With the OpenShift CLI there are three ways to create a new application, by specifying either:
Pointing oc new-app at source code kicks off a chain of events, for our example run:
$ oc new-app https://github.com/sclorg/nodejs-ex -l name=myapp
The tool will inspect the source code, locate an appropriate image on DockerHub, create an ImageStream for that image, and then create the right build configuration, deployment configuration and service definition.
(The -l flag will apply a label of "name=myapp" to all the resources created by new-app, for easy management later.)
We can also create new apps using OpenShift template files. Clone the demo app source code from GitHub repo (fork if you like).
$ git clone https://github.com/sclorg/nodejs-ex
Looking at the repo, you'll notice three files in the openshift/template directory:
nodejs-ex
├── openshift
│ └── templates
│ ├── nodejs.json
│ ├── nodejs-mongodb.json
│ └── nodejs-mongodb-persistent.json
├── package.json
├── README.md
├── server.js
├── tests
│ └── app_test.js
└── views
└── index.html
We can create the the new app from the nodejs.json template by using the -f flag and pointing the tool at a path to the template file:
$ oc new-app -f /path/to/nodejs.json
oc new-app will kick off a build once all required dependencies are confirmed.
Check the status of your new nodejs app with the command:
$ oc status
Which should return something like:
In project nodejs (nodejs-echo) on server https://10.2.2.2:8443
svc/nodejs-ex - 172.30.108.183:8080
dc/nodejs-ex deploys istag/nodejs-ex:latest <-
bc/nodejs-ex builds https://github.com/sclorg/nodejs-ex with openshift/nodejs:0.10
build #1 running for 7 seconds
deployment #1 waiting on image or update
Note the server address for the web console, as yours will likely differ if you're not using the Vagrant set-up. You can follow along with the web console to see what new resources have been created and watch the progress of builds and deployments.
If the build is not yet started (you can check by running oc get builds), start one and stream the logs with:
$ oc start-build nodejs-ex --follow
You can alternatively leave off --follow and use oc logs build/nodejs-ex-n where n is the number of the build to track the output of the build.
Deployment happens automatically once the new application image is available. To monitor its status either watch the web console or execute oc get pods to see when the pod is up. Another helpful command is
$ oc get svc
This will help indicate what IP address the service is running, the default port for it to deploy at is 8080. Output should look like:
NAME CLUSTER-IP EXTERNAL-IP PORT(S) SELECTOR AGE
nodejs-ex 172.30.249.251 <none> 8080/TCP deploymentconfig=nodejs-ex,name=myapp 17m
An OpenShift route exposes a service at a host name, like www.example.com, so that external clients can reach it by name.
DNS resolution for a host name is handled separately from routing; you may wish to configure a cloud domain that will always correctly resolve to the OpenShift router, or if using an unrelated host name you may need to modify its DNS records independently to resolve to the router.
That aside, let's explore our new web console, which for our example is running at https://10.2.2.2:8443.
After logging into the web console with your same CLI oc login credentials, click on the project we just created, then click Create route.
If you're running OpenShift on a local machine, you can preview the new app by setting the Hostname to a localhost like: 10.2.2.2.
This could also be accomplished by running:
$ oc expose svc/nodejs-ex --hostname=www.example.com
Now navigate to the newly created Node.js web app at the hostname we just configured, for our example it was simply https://10.2.2.2.
You may have noticed the index page "Page view count" reads "No database configured". Let's fix that by adding a MongoDB service. We could use the second OpenShift template example (nodejs-mongodb.json) but for the sake of demonstration let's point oc new-app at a DockerHub image:
$ oc new-app centos/mongodb-26-centos7 \
-e MONGODB_USER=admin \
-e MONGODB_DATABASE=mongo_db \
-e MONGODB_PASSWORD=secret \
-e MONGODB_ADMIN_PASSWORD=super-secret
The -e flag sets the environment variables we want used in the configuration of our new app.
Running oc status or checking the web console will reveal the address of the newly created MongoDB:
In project nodejs-echo on server https://10.2.2.2:8443
svc/mongodb-26-centos7 - 172.30.0.112:27017
dc/mongodb-26-centos7 deploys istag/mongodb-26-centos7:latest
deployment #1 running for 43 seconds - 1 pod
http://10.2.2.2 to pod port 8080-tcp (svc/nodejs-ex)
dc/nodejs-ex deploys istag/nodejs-ex:latest <-
bc/nodejs-ex builds https://github.com/sclorg/nodejs-ex with openshift/nodejs:0.10
deployment #1 deployed 14 minutes ago - 1 pod
Note that the url for our new Mongo instance, for our example, is 172.30.0.112:27017, yours will likely differ.
To take a look at environment variables set for each pod, run oc env pods --all --list.
We need to add the environment variable MONGO_URL to our Node.js web app so that it will utilize our MongoDB, and enable the "Page view count" feature. Run:
$ oc set env dc/nodejs-ex MONGO_URL='mongodb://admin:secret@172.30.0.112:27017/mongo_db'
Then check oc status to see that an updated deployment has been kicked off:
In project nodejs-echo on server https://10.2.2.2:8443
svc/mongodb-26-centos7 - 172.30.0.112:27017
dc/mongodb-26-centos7 deploys istag/mongodb-26-centos7:latest
deployment #1 deployed 2 hours ago - 1 pod
http://10.2.2.2 to pod port 8080-tcp (svc/nodejs-ex)
dc/nodejs-ex deploys istag/nodejs-ex:latest <-
bc/nodejs-ex builds https://github.com/sclorg/nodejs-ex with openshift/nodejs:0.10
deployment #2 deployed about a minute ago - 1 pod
deployment #1 deployed 2 hours ago
You should now have a Node.js welcome page showing the current hit count, as stored in a MongoDB database.
Assuming you used the URL of your own forked repository, we can easily push changes and simply repeat the steps above which will trigger the newly built image to be deployed.
Review some of the common tips and suggestions here.
To run this example from the Web UI, you can same steps following done on the CLI as defined above. Here's a video showing it in motion:
If you get stuck at some point, or think that this document needs further details or clarification, you can give feedback and look for help using the channels mentioned in the OpenShift Origin repo, or by filing an issue.
This repository is compatible with Node.js 4 and higher, excluding any alpha or beta versions.
This code is dedicated to the public domain to the maximum extent permitted by applicable law, pursuant to CC0.