9.9 Demo lab: show Docker alternatives on Application Migration and Modernization Techlab

9.9.1 Build a container image

Mon, 01 Jan 0001 00:00:00 +0000

This is a demo lab because your WEB-IDE does not contain the needed tools. Ask the moderator for a demo or install the tools on your computer.

Task 9.9.1.1: Build a container image

The build can be done using any container building tool that supports Dockerfile builds.

The sample application is an HTTP server written in the Go programming language .

The following files are needed inside your application repository:

Dockerfile
main.go

Sample go application

This Go code defines an HTTP server listening on port 8080. It has to be placed in the main.go file.

9.9.2 Deploy a container image

Mon, 01 Jan 0001 00:00:00 +0000

Task 9.9.2.2: Deploy a container image

As you know from other techlabs, an easy way to create applications in OpenShift is using oc new-app

Let’s create an application for the go-hello-world image that we built before.

oc new-app appuio/go-hello-world --as-deployment-config

Since OpenShift 4.5 oc new-app creates a Deployment not a DeploymentConfig. We let it create a DeploymentConfig by adding the --as-deployment-config flag.

--> Found container image 5779c56 (11 days old) from for "appuio/go-hello-world:latest"

 * This image will be deployed in deployment config "go-hello-world"
 * Port 8080/tcp will be load balanced by service "go-hello-world"
 * Other containers can access this service through the hostname "go-hello-world"

--> Creating resources ...
 deploymentconfig.apps.openshift.io "go-hello-world" created
 service "go-hello-world" 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 svc/go-hello-world'
 Run 'oc status' to view your app.

To access the application from outside OpenShift, a route is needed:

9.9.3 Docker Instructions

Mon, 01 Jan 0001 00:00:00 +0000

9.9.3.1 Docker instructions

Building, testing and publishing of the container image using Docker .

Image build

Docker build command:

docker build -t go-hello-world

Image test

Docker run command:

docker run -p 8080:8080 -ti go-hello-world

It can be tested with a browser (http://localhost:8080/world ) or using curl:

curl localhost:8080/world

Publish image to Docker Hub

docker login
docker tag go-hello-world:latest appuio/go-hello-world:latest
docker push appuio/go-hello-world:latest