anupamuap/devops-dotnetforopenshiftcrc

Create a simple Hello World .Net 5 application and run it on Red Hat OpenShift (Code Ready Container example)

Run .Net code on Red Hat OpenShift Container Platform on Mac OS

Create a simple Hello World .Net 5 application and run it on a local instance of Red Hat OpenShift AKA Code Ready Containers. See how easy it is to get started with development on OpenShift Container Platform (OCP). OCP supports many languages and you can easily bring your .Net code to the world of containers and Kubernetes with OCP.

Updated 19 May 2021

Pre-req .Net 5 SDK

• Note: I'm using a Mac for this example.
• Download and install .Net 5 SDK for your OS.
• Note: For this tutorial I used Microsoft's installation package for SDK 5.0.203

• Install the .Net SDK per the instructions for your OS

• Test your .Net SDK installation

  % dotnet --version
  5.0.23
  

Install Red Hat CodeReady Containers

• Download the Red Hat CodeReady Container (CRC) for you OS here Create an OpenShift cluster
• Chose the "local" tab and select your OS.
• After you download CRC, click the Download pull secret

• After you download the code run the installer. The latest release of CRC takes care of installing CRC for you.

Prep your CodeReady Containers environment

• After installing CRC, we will do the rest of the work on the command line. On the Mac open a Terminal window. I placed the pull secret in my home Documents folder in a folder I labeled crc. On the Mac or Linux it might look like this: ~/Documents/crc

  % cp pull-secret\(1\) ~/Documents/crc/pull-secret.txt
  

• Check the CRC version. As of 5/18/2021 the latest release was 1.26 with OpenShift 4.7.9

  % crc version
  CodeReady Containers version: 1.26.0+31f06c09
  OpenShift version: 4.7.8 (not embedded in executable)
  

• Run the setup command to download the CRC bundle and prep your environment. This typically takes a few mintues.

  % crc setup
  <output omitted>
  

Start up CRC

• Start up crc an include the pull secret you previously downloaded

    % crc start -p ~/Documents/crc/pull-secret.txt
  

• Depending on your hardware, it make several minutes for CRC to startup. Be sure to copy the login information that is displayed on the console after starting CRC. See example output below.

Started the OpenShift cluster.

The server is accessible via web console at:
  https://console-openshift-console.apps-crc.testing

Log in as administrator:
  Username: kubeadmin
  Password: TDjTx-BwDqi-vDvqA-VAxJz

Log in as user:
  Username: developer
  Password: developer

Use the 'oc' command line interface:
  $ eval $(crc oc-env)
  $ oc login -u developer https://api.crc.testing:6443

Create a sample Hello World .Net web app

Now let's create our sample .Net application. Chose a directory wher you would like to store your sample appication. I created my sample Hello World .Net web app in a directory called projects

   % dotnet new webApp -o myWebApp --no-https

• When the sample app code has finished generating change into the applicaiton's directory and start up the applicaiton.

   % cd myWebApp
   % dotnet run
  

• The app starts up quickly and is ready to test when Contentr root path:... on the treminal screend. Follow the instructions to access the application via a browser.

• The URL for the app is likely: http://localhost:5000

• When you are finished type Ctrl-c from the terminal window to stop server.

Modify the .Net code

Let's change the "Welcome" message to "Welcome from OpenShift Container Platform!".

• Navigate to the Pages directory under your project.

  % cd Pages
  

• In the Pages directory open the file titled Index.cshtml with your favorite editor.

  % nano Index.cshtml
  

• Change the following line:

  <h1 class="display-4">Welcome</h1>
  

• to:

  <h1 class="display-4">Welcome to OpenShift Container Platform!</h1>
  

• My file looked like this...

@page
@model IndexModel
@{
    ViewData["Title"] = "Home page";
}

<div class="text-center">
    <h1 class="display-4">Welcome to OpenShift Container Platform</h1>
    <p>Learn about <a href="https://docs.microsoft.com/aspnet/core">building Web apps with ASP.NET Core</a>.</p>
</div>

• Go back to the "root" of your project folder and rerun the application to see the changed message

  % cd ..
  % dotnet run
  

• When finished type Ctrl-c in the terminal window to stop the server.

Prep app for OCP

• Use the following command to make the .Net app ready for the OCP build and deploy process. The dotnet publish command preps the applicaiton for deployment storing the artifacts in a folder. The -f swith sets the framework to .Net 5.0 and -c switch defines the build configuration

  % cd ..
  % dotnet publish myWebApp -f net5.0 -c Release
  

• You are ready to go when see the statement All projcets are up-to-date.... in the terminal window.

Prep OCP for .Net

• Login to OCP as developerl

  % eval $(crc oc-env)
  % oc login -u developer https://api.crc.testing:6443
  

• To see who you are logged in as type the following

  % oc whoami
  developer
  

• Create a new OCP project (K8s namespace) for our .Net Welcome application.

  % oc new-project my-first-app
  

• You can check the project you are currently in with the following oc command:

  % oc get projects
  NAME           DISPLAY NAME   STATUS
  my-first-app                  Active
  

• If this is your first .Net project in CRC, then you'll need to add a .Net imagestreams. Imagestreams makes it easy to build and deploy our .Net app in a container and can be used to trigger new deployments when a new image becomes available See links below for more informaton on Imagestreams

  % oc create -f https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/dotnet_imagestreams.json
  % oc replace -f https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/dotnet_imagestreams.json
  

Build, Deploy and access your new .Net app

• Create a new build configuration. We will use a Red Hat Universal Base Image (ubi8) that includes the .Net 5 SDK and runtimes. UBI containers are OCI-compliant. We are building the app from binary contents.

  % oc new-build --name=my-web-app dotnet:5.0-ubi8 --binary=true
  

--> Found image b264294 (13 days old) in image stream "my-first-app/dotnet" under tag "5.0-ubi8" for "dotnet:5.0-ubi8"

    .NET 5 
    ------ 
    Platform for building and running .NET 5 applications

    Tags: builder, .net, dotnet, dotnetcore, dotnet-50

    * A source build using binary input will be created
      * The resulting image will be pushed to image stream tag "my-web-app:latest"
      * A binary build was created, use 'oc start-build --from-dir' to trigger a new build

--> Creating resources with label build=my-web-app ...
    imagestream.image.openshift.io "my-web-app" created
    buildconfig.build.openshift.io "my-web-app" created
--> Success

• Start the build and specify the path to the binary artifacts in .Net project (I'm at the "root" of my project folder myWebApp).

  % oc start-build my-web-app --from-dir=bin/Release/net5.0/publish
  

Uploading directory "bin/Release/net5.0/publish" as binary input for the build ...
...........
Uploading finished
build.build.openshift.io/my-web-app-1 started

• You can also check the logs to see if the build is completed.

  % oc logs -f bc/my-web-app
  

• Create our new application on OCP.

  % oc new-app my-web-app
  

--> Found image 4dff9a4 (10 minutes old) in image stream "my-first-app/my-web-app" under tag "latest" for "my-web-app"

    .NET 5 
    ------ 
    Platform for building and running .NET 5 applications

    Tags: builder, .net, dotnet, dotnetcore, dotnet-50


--> Creating resources ...
    deployment.apps "my-web-app" created
    service "my-web-app" created
--> Success
    Application is not exposed. You can expose services to the outside world by executing one or more of the commands below:
     'oc expose service/my-web-app' 
    Run 'oc status' to view your app.

• You can check the status of your app.

  % oc status
  

In project my-first-app on server https://api.crc.testing:6443

svc/my-web-app - 10.217.4.30:8080
  deployment/my-web-app deploys istag/my-web-app:latest <-
    bc/my-web-app source builds uploaded code on istag/dotnet:5.0-ubi8 
    deployment #2 running for 46 seconds - 1 pod
    deployment #1 deployed 46 seconds ago


1 info identified, use 'oc status --suggest' to see details.

• At this point we can log into the OCP console and see our application.

• Click on the Topology tab on the left side and the click the my-web-app project link.

• Hover over the app icon and click on the blue arrow to see more detail about our application. Notice there is no route defined to get to our application. A service is created when we created a new application, but we need to expose that service via a route to access our application from outside the OCP cluster

• Back at the command line let's make our app available to the outside world.

  % oc expose service/my-web-app
  route.route.openshift.io/my-web-app exposed
  

• Get the the URL to your app.

  # oc status
  

In project my-first-app on server https://api.crc.testing:6443

http://my-web-app-my-first-app.apps-crc.testing to pod port 8080-tcp (svc/my-web-app)
  deployment/my-web-app deploys istag/my-web-app:latest <-
    bc/my-web-app source builds uploaded code on istag/dotnet:5.0-ubi8 
    deployment #2 running for 8 minutes - 1 pod
    deployment #1 deployed 8 minutes ago


1 info identified, use 'oc status --suggest' to see details.

• Back at the OCP console we now see our app is available to the outside world. You can click on the link in the Routes section to access your application.

Access the OCP console to see your project and app

• No we can see our application running on OCP. My URL looked like this: https://console-openshift-console.apps-crc.testing

References

• GETTING STARTED WITH .NET ON RHEL 8
• Getting Strated Guide - CodeReady Containers 1.26
• Managing Imagestreams OCP 4.7