Getting Started with Data Grid on OpenShift

Difficulty: intermediate

Estimated Time: 5-10 minutes

Learning Objectives

This interactive tutorial shows you how to deploy and run a single instance of RHDG Red Hat Data Grid on OpenShift.

You then learn how to expose the REST endpoint and invoke simple cache operations.

Introduction to Red Hat Data Grid

Red Hat Data Grid (RHDG) is an open source, in-memory data store that:

Stores data in memory (RAM) to provide fast, low-latency response times and very high throughput.
Synchronizes data across multiple nodes for continuous availability, reliability, and elastic scalability.
Offers flexibility. You can use it as a distributed cache, NoSQL database, or event broker.

RHDG capabilities improve application performance and scalability while reducing the need to make expensive calls to database management systems and transactional back ends.

In this tutorial, you got an overview of Red Hat Data Grid and learned how easy it is to invoke basic cache operations over REST.

Check out some of the other components in Red Hat OpenShift Application Runtimes, such as the Vert.x scenario to learn about other runtimes available from Red Hat.

Your environment is currently being packaged as a Docker container and the download will begin shortly. To run the image locally, once Docker has been installed, use the commands

cat scrapbook_openshift/enterprise-java_rhoar-getting-started-rhdg_container.tar | docker load

docker run -it /openshift/enterprise-java_rhoar-getting-started-rhdg:

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Step 1 of 3

Login to OpenShift

Red Hat OpenShift Container Platform is the preferred runtime for Red Hat Data Grid and is based on the Kubernetes container-orchestration system.

If you are new to OpenShift, you should complete Introduction to OpenShift before you start this tutorial.

1. Logging in to OpenShift

Run the oc login command as follows:

oc login -u developer -p developer

This command authenticates you to OpenShift with the following credentials:

Username: developer
Password: developer

2. Creating a project

Create a project for your RHDG application as follows:

oc new-project example --display-name="Simple RHDG REST App"

3. Opening the OpenShift console

OpenShift provides a console that lets you work with application deployments from a browser window.

Select the "OpenShift Console" tab to launch the console in your browser.
Enter your credentials when prompted to authenticate and then select "Log in". The console displays the projects that you can work with.
Select the "Simple RHDG REST App" project that you created to view all of the resources available in your project:

At the moment your project does not have any available applications or resources. Proceed to the next section and start creating a deployment.

Deploy Data Grid to OpenShift

In this section, you deploy a single instance of Red Hat Data Grid (RHDG) that exposes cached data through a REST endpoint.

1. Deploying RHDG

Run the oc new-app command to pull an image from the RHDG repository and create a service named rhdg as follows:

oc new-app registry.access.redhat.com/jboss-datagrid-7/datagrid71-openshift:latest --name rhdg

The command output is:


--> Creating resources ...
    imagestream "rhdg" created
    deploymentconfig "rhdg" created
    service "rhdg" created
--> Success
    Run 'oc status' to view your app.

2. Exposing an external service route

Run the oc expose command to expose the rhdg externally to OpenShift as follows:

oc expose svc rhdg --name=rhdgroute

You can use the oc describe command to view details about the rhdgroute route as follows:

oc describe route rhdgroute

The command output is similar to:

Name:                   rhdgroute
Namespace:              example
Created:                5 minutes ago
Labels:                 app=rhdg
Annotations:            openshift.io/host.generated=true
Requested Host:         jdgroute-example.2886795312-80-simba02.environments.katacoda.com
                          exposed on router router 5 minutes ago
Path:                   <none>
TLS Termination:        <none>
Insecure Policy:        <none>
Endpoint Port:          8080-tcp

Service:        rhdg
Weight:         100 (100%)
Endpoints:      172.20.0.3:8080, 172.20.0.3:11333, 172.20.0.3:8443 + 3 more...

Now that you have a single RHDG instance running on OpenShift with an external route, you can start manipulating data in the cache.

Perform cache operations over REST

Red Hat Data Grid (RHDG) supports REST out of the box so you can invoke cache operations with these HTTP methods:

GET: retrieves cache entries.
POST: creates new cache entries under specified keys.
DELETE: deletes cache entries.
PUT: updates cache entries.

The URLs through which you invoke cache operations contain cache and key namesIn addition, the invocation URL contains cache name and key name in its address. You'll see this encoding method in the examples below.

1. Retrieving cache entries

Invoke a GET operation on the key named "a" in the cache named "default" with the following command:

curl -i -H "Accept:application/json" http://rhdgroute-example.[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com/rest/default/a

As expected, key "a" does not exist in the default cache and the command returns a 404 HTTP error:

HTTP/1.1 404 Not Found
Server: nginx/1.11.9
Date: Wed, 24 Jan 2018 15:28:22 GMT
Content-Type: text/plain; charset=utf-8
Content-Length: 0
Connection: keep-alive

2. Inserting entries into the cache

Insert a JSON entry {"name":"Red Hat Data Grid"} as the value for the key named "a" in the default cache with the following command:

curl -X POST -i -H "Content-type:application/json" -d "{\"name\":\"Red Hat Data Grid\"}" http://rhdgroute-example.[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com/rest/default/a

Now key "a" exists in the default cache and has a JSON value. If you retrieve the entry again, it is successful:

curl -i -H "Accept:application/json" http://rhdgroute-example.[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com/rest/default/a

3. Updating cache entries

Update the cache entry and replace the value of key "a" with a different JSON entry {"name":"Infinispan"} with the following command:

curl -X PUT -i -H "Content-type:application/json" -d "{\"name\":\"Infinispan\"}" http://rhdgroute-example.[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com/rest/default/a

Retrieve the entry again to verify the updated value:

curl -i -H "Accept:application/json" http://rhdgroute-example.[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com/rest/default/a

4. Deleting cache entries

Delete key "a" from the default cache with the following command:

curl -X DELETE -i http://rhdgroute-example.[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com/rest/default/a

Attempt to retrieve the entry to verify that it is deleted:

curl -i -H "Accept:application/json" http://rhdgroute-example.[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com/rest/default/a

A 404 HTTP error is returned because you deleted the entry from the cache.

Congratulations

Now that you've successfully completed this tutorial you're ready to start learning more about RHDG capabilities.

Head over to the Quickstarts on GitHub where you can find code examples with how-to and best practice demonstrations for running RHDG on OpenShift.

You can also find lots of information in the Red Hat Data Grid documentation.

Terminal

Local Web Browser

OpenShift Console

cd <directory>	Change directory
ls	List directory
echo 'contents' > <file>	Write contents to a file
cat <file>	Output contents of file

i	In Command Mode	Change into Insert Mode, you can now insert and edit text in the file
esc	In Insert Mode	Change into Command Mode, you can now execute commands
:wq	In Command Mode	Save and Exit

Welcome!

Getting Started with Data Grid on OpenShift

Learning Objectives

Introduction to Red Hat Data Grid

Congratulations!

You've completed the scenario!

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