Kubernetes: Deploy a Spring Boot Application

Before You Begin

To successfully perform this tutorial, you must have the following:

For Container Registry, Kubernetes and Load Balancers:
- A paid Oracle Cloud Infrastructure account.
- See Signing Up for Oracle Cloud Infrastructure.
For building applications and Docker images:
- One of the following local environments:
  - A MacOS or Linux machine.
  - A Windows machine with Linux support. For example:
    - Windows Subsystem for Linux
    - Oracle Virtual Box
- The following applications on your local environment:
  - JDK 11 and set JAVA_HOME in .bashrc.
  - Python 3.6.8+ and pip installer for Python 3
  - Kubernetes Client 1.11.9+
  - Apache Maven 3.0+
  - Docker 19.0.3+
  - Git 1.8+

If you want to use an OCI Free Tier Linux compute instance to manage your deployment, the following sections provide information to get the required software installed.

Install a Linux Instance

Install JDK

Verify your current installation:
```
java -version
```

To install JDK 11, run the following commands:

Oracle Linux:

sudo yum update

yum list jdk*

sudo yum install -y <jdk-version-of-your-choice>

Ubuntu:

sudo apt update

sudo apt install -y openjdk-11-jdk-headless

Verify the installation.
```
java -version
```

Set JAVA_HOME in .bashrc.

Update the file:

vi .bashrc

In the file, append the following text and save the file:

# set JAVA_HOME
export JAVA_HOME=<path-to-jdk>

Examples:

# set JAVA_HOME in Oracle Linux
export JAVA_HOME=/usr/java/jdk-11.0.10

# set JAVA_HOME in Ubuntu
export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64

Activate the preceding command in the current window.
```
source ~/.bashrc
```

Install Python 3 and Pip 3

Verify your current installation.
```
python3 --version
```

For Python 3, run the following commands:

Oracle Linux:

sudo yum update

sudo yum install -y python3

Ubuntu:

sudo apt update

sudo apt install -y python3

Verify the pip installation for Python3.
```
pip3 -V
```
Example output if pip for Python3 is installed:
```
pip <version> from xxx/lib/python3.x/site-packages/pip (python 3.x)
```

To install pip for Python 3, run the following commands:

Oracle Linux:

sudo yum update

sudo yum install -y python3-pip

Ubuntu:

sudo apt update

sudo apt install -y python3-pip

Verify the pip for Python 3 installation.
```
pip3 -V
```

Install Kubernetes Client

Verify your current installation:
```
kubectl version --client
```
If you have Kubernetes, then the version is <major-version>.<minor-version>. For example, for version 1.20, you get the following:
```
version.Info{Major:"1", Minor:"20"...
```
To install he kubectl client, refer to the following links:
- Install Kubernetes client on Linux
- Install Kubernetes client on MacOS
Verify the installation.
```
kubectl version --client
```

Install Apache Maven

Verify your current installation.
```
mvn --version
```
To install Apache Maven, refer to the following links:
- Download Apache Maven
- Install Apache Maven
Verify the installation.
```
mvn --version
```

Install Docker

Verify your current installation:
```
docker -v
```
Oracle Linux
To install Docker on Oracle Linux, run the following commands.
```
sudo yum install docker-engine
```
```
sudo systemctl start docker
```
```
sudo systemctl enable docker
```
Note: The last command enables Docker to start on reboots.
Ubuntu Linux
To install Docker on Ubuntu Linux, refer to the following link: Get Docker
Verify the installation.
```
docker -v
```

1. Prepare

Prepare your environment to create and deploy your application.

Check your Service Limits

Log in to the Oracle Cloud Infrastructure Console.
Open the navigation menu, and click Governance and Administration. Under Governance, click Limits, Quotas and Usage.
Find your service limit for Regions:
- Filter for the following options:
  - Service: Regions
  - Scope: Tenancy
  - Resource: Subscribed region count
  - Compartment: <tenancy-name> (root)
- Find service limit:
  - Limit Name: subscribed-region-count
  - Service Limit: minimum 2
Find your available Compute core count for the VM.Standard.E3.Flex shape:
- Filter for the following options:
  - Service: Compute
  - Scope: <first-availability-domain>. Example: EMlr:US-ASHBURN-AD-1
  - Resource: Cores for Standard.E3.Flex and BM.Standard.E3.128 Instances
  - Compartment: <tenancy-name> (root)
- Find available core count:
  - Limit Name: standard-e3-core-ad-count
  - Available: minimum 1
- Repeat for Scope: <second-availability-domain> and <third-availability-domain>. Each region must have at least one core available for this shape.
Find out if you have 50 GB of Block Volume available:
- Filter for the following options:
  - Service: Block Volume
  - Scope: <first-availability-domain>. Example: EMlr:US-ASHBURN-AD-1
  - Resource Volume Size (GB)
  - Compartment: <tenancy-name> (root)
- Find available block volume storage:
  - Limit Name: total-storage-gb
  - Available: minimum 50
- Repeat for Scope: <second-availability-domain> and <third-availability-domain>. Each region must have at least 50 GB of block volume available.
Find out how many Flexible Load Balancers you have available:
- Filter for the following options:
  - Service: LbaaS
  - Scope: <your-region>. Example: us-ashburn-1
  - Resource: <blank>
  - Compartment: <tenancy-name> (root)
- Find the number of available flexible load balancers:
  - Limit Name: lb-flexible-count
  - Available: minimum 1

Note

This tutorial creates three compute instances with a VM.Standard.E3.Flex shape for the cluster nodes. To use another shape, filter for its core count. For example, for VM.Standard2.4, filter for Cores for Standard2 based VM and BM Instances and get the count.

For a list of all shapes, see VM Standard Shapes.

Note

This tutorial uses a 'Quick Create' workflow to create a cluster with a public regional subnet that hosts a flexible load balancer. To use a different load balancer, you can use a custom workflow to explicitly specify which existing network resources to use, including the existing subnets in which to create the load balancers.

To use another bandwidth for the load balancer, filter for its count, for example 100-Mbps bandwidth or 400-Mbps bandwidth.

Create an Authorization Token

Gather Required Information

Set up OCI Command Line Interface

Install a Python Virtual Environment and Wrapper

The Python virtualenv creates a folder that contains all the executables and libraries for your project.

The virtualenvwrapper is an extension to virtualenv. It provides a set of commands, which makes working with virtual environments much more pleasant. It also places all your virtual environments in one place. The virtualenvwrapper provides tab-completion on environment names.

Install virtualenv.
```
pip3 install --user virtualenv
```
Install virtualenvwrapper.
```
pip3 install --user virtualenvwrapper
```
Find the location of the virtualenvwrapper.sh script.
```
grep -R virtualenvwrapper.sh
```
Example paths:
- Linux example: /home/ubuntu/.local/bin/virtualenvwrapper.sh
- MacOS example: /usr/local/bin/virtualenvwrapper.sh
Configure the virtual environment wrapper in .bashrc.
```
sudo vi .bashrc
```
Append the following text.
```
# set up Python env
export WORKON_HOME=~/envs
export VIRTUALENVWRAPPER_PYTHON=/usr/bin/python3
export VIRTUALENVWRAPPER_VIRTUALENV_ARGS=' -p /usr/bin/python3 '
source <path-to-virtualenvwrapper.sh>
```
Replace <path-to-virtualenvwrapper.sh> with its value.
Based on the location of Python3 binaries in your environment, update /usr/bin/python3 to its correct location.
Save the file.

Activate the commands in the current window.

source ~/.bashrc

Example output:

virtualenvwrapper.user_scripts creating /home/ubuntu/envs/premkproject
virtualenvwrapper.user_scripts creating /home/ubuntu/envs/postmkproject
virtualenvwrapper.user_scripts creating /home/ubuntu/envs/initialize
virtualenvwrapper.user_scripts creating /home/ubuntu/envs/premkvirtualenv
virtualenvwrapper.user_scripts creating /home/ubuntu/envs/postmkvirtualenv
virtualenvwrapper.user_scripts creating /home/ubuntu/envs/prermvirtualenv
virtualenvwrapper.user_scripts creating /home/ubuntu/envs/postrmvirtualenv
virtualenvwrapper.user_scripts creating /home/ubuntu/envs/predeactivate
virtualenvwrapper.user_scripts creating /home/ubuntu/envs/postdeactivate
virtualenvwrapper.user_scripts creating /home/ubuntu/envs/preactivate
virtualenvwrapper.user_scripts creating /home/ubuntu/envs/postactivate

Install OCI CLI

Start a virtual environment.
```
workon cli-app
```
Confirm that the name of your virtual environment, cli-app appears in the left of your command prompt.
Example: (cli-app) ubuntu@<ubuntu-instance-name>:~$
Install OCI CLI.
```
pip3 install oci-cli
```
Test the installation:
```
oci --version
```
If everything is set up correctly, you get the version.
```
oci --help
```

Configure the OCI CLI

Enter the following command in your virtual environment:
```
oci setup config
```
Enter your answers from the Gather Required Information section:
- Location for your config [$HOME/.oci/config]: <take-default>
- User OCID: <user-ocid>
- Tenancy OCID: <tenancy-ocid>
- Region (e.g. us-ashburn-1): <region-identifier>
Enter the following information to set up your OpenSSL API encryption keys:
- Generate a new API Signing RSA key pair? [Y/n]: Y
- Directory for your keys [$HOME/.oci]: <take-default>
- Name for your key [oci_api_key] <take-default>
Deactivate the virtual environment:
```
deactivate
```
The (cli-app) prefix in your environment is not displayed anymore.

Note

Your private key is oci_api_key.pem and your public key is oci_api_key_public.pem.

Add the Public Key to Your User Account.

Activate the cli-app environment:
```
workon cli-app
```
Display the public key.
```
cat $HOME/.oci/oci_api_key_public.pem
```
Copy the public key.
Add the public key to your user account:
- Go to the Console.
- In the navigation menu , select the Profile menu and then select User settings or My profile, depending on the option that you see.
- Click API Keys.
- Click Add API Key.
- Click Paste Public Key.
- Paste value from previous step, including the lines with BEGIN PUBLIC KEY and END PUBLIC KEY.
- Click Add.

Note

Whenever you want to use the OCI CLI, activate it with: workon cli-app
When you change project names, workon deactivates your current working environment. This way, you can quickly switch between environments.

2. Set Up a Cluster

Install and configure management options for your Kubernetes cluster. Later, deploy your application to this cluster.

Add Compartment Policy

If your username is in the Administrators group, then skip this section. Otherwise, have your administrator add the following policy to your tenancy:

allow group <the-group-your-username-belongs> to manage compartments in tenancy

With this privilege, you can create a compartment for all the resources in your tutorial.

Steps to Add the Policy

In the navigation menu , select the Profile menu and then select User settings or My profile, depending on the option that you see.
In the left pane, click Groups.
In a notepad, copy the Group Name that your username belongs.
Open the navigation menu and click Identity & Security. Under Identity, click Policies.
Select your compartment from the Compartment drop-down.
Click Create Policy.
Fill in the following information:
- Name: manage-compartments
- Description: Allow the group <the-group-your-username-belongs> to list, create, update, delete and recover compartments in the tenancy.
- Compartment: <your-tenancy>(root)
For Policy Builder, click Show manual editor.

Paste in the following policy:

allow group <the-group-your-username-belongs> to manage compartments in tenancy

Click Create.

Reference: The compartments resource-type in Verbs + Resource-Type Combinations for IAM

Create a Compartment

Add Resource Policy

If your username is in the Administrators group, then skip this section. Otherwise, have your administrator add the following policy to your tenancy:

allow group <the-group-your-username-belongs> to manage all-resources in compartment <your-compartment-name>

With this privilege, you can manage all resources in your compartment, essentially giving you administrative rights in that compartment.

Steps to Add the Policy

Create a Cluster with 'Quick Create'

Set Up Local Access to Your Cluster

After you create a Kubernetes cluster, set up your local system to access the cluster.

Sign in to the Oracle Cloud Infrastructure Console.
Open the navigation menu and click Developer Services. Under Containers & Artifacts, click Kubernetes Clusters (OKE).
Click the link to <your-cluster>.

The information about your cluster is displayed.
Click Access Cluster.
Click Local Access.
Follow the steps provided in the dialog. They are reprinted here for your reference.

Note

If you are not in your virtual environment, enter: workon cli-app before you run kubectl commands.
Check your oci CLI version.
```
oci -v
```
Make your .kube directory if it doesn't exist.
```
mkdir -p $HOME/.kube
```
Create a kubeconfig file for your setup. Use the information from Access Your Cluster dialog.
```
oci ce cluster create-kubeconfig <use data from dialog>
```
Export the KUBECONFIG environment variable.
```
export KUBECONFIG=$HOME/.kube/config
```
Note

If you want to have the environment variable start in a new shell, then add export KUBECONFIG=$HOME/.kube/config to your ~/.bashrc file.
Test your cluster configuration with the following commands.
List clusters:
```
kubectl get service
```
Get deployment details:
```
kubectl describe deployment
```
Get pods:
```
kubectl get pods
```
Note

Since no application is deployed, the last two commands produce: "No resources found in default namespace."
Note

To look at a different cluster, specify a different config file on the command line. Example:
```
kubectl --kubeconfig=</path/to/config/file>
```

With your cluster access set up, you are now ready to prepare your application for deployment.

3. Build a Local Application

Build a local application and a Docker image for the application.

Create a Local Application

Make a copy of the Spring Boot Docker guide with Git:

git clone https://github.com/spring-guides/gs-spring-boot-docker.git

Change into the gs-spring-boot-docker/initial directory.
```
cd gs-spring-boot-docker/initial
```
Change into the Java source directory: src/main/java/hello.
```
cd src/main/java/hello
```

Update Application.java with the following code:

package hello;
                        
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
@RestController
public class Application {
	
	@RequestMapping("/")
	public String home() {
		return "<h1>Spring Boot Hello World!</h1>";
	}

	public static void main(String[] args) {
		SpringApplication.run(Application.class, args);
	}

}

Save the file.

Run the Local Application

Change into the gs-spring-boot-docker/initial directory.

Package the app:

mvn package

Example output:

[INFO] Replacing main artifact with repackaged archive
[INFO] BUILD SUCCESS

Run the app:

java -jar target/spring-boot-docker-0.0.1-SNAPSHOT.jar

Example output:

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (vx.x.x)

hello.Application: Started Application in x seconds (JVM running for x.x)

Keep the code running and test the app in one of the following ways:
- In a new terminal connected to your instance, enter the following code:
```
curl -X GET http://localhost:8080
```
  Output:
```
<h1>Spring Boot Hello World!</h1>
```
- Load the following address in a browser:
```
localhost:8080
```
  You can use the second option, only if your environment is local.
Stop the running application. Example: Ctrl + C

Build a Docker Image

A Docker image holds an application, its dependencies, and instructions to run the application.

Note

For MacOS, you can remove the sudo in the docker commands.

Change into the gs-spring-boot-docker/initial directory.

Create a file named Dockerfile.

FROM openjdk:8-jdk
RUN addgroup --system spring && adduser --system spring -ingroup spring
USER spring:spring
ARG JAR_FILE=target/*.jar
COPY ${JAR_FILE} app.jar
ENTRYPOINT ["java","-jar","/app.jar"]

Build the Docker image:

sudo docker build -t spring-boot-hello .

Example output:

Successfully built xxxxxxxxxxxx
Successfully tagged spring-boot-hello:latest

Run the Docker image:
```
sudo docker run -p 8080:8080 -t spring-boot-hello
```
You get the same result as running the local app.
Stop the running application.

Congratulations! You have successfully created a Spring Boot Docker image.

References:

4. Deploy Your Docker Image

Push your Spring Boot Docker image to OCI Container Registry. Then use the image to deploy your application.

Create a Docker Repository

Open the navigation menu and click Developer Services. Under Containers & Artifacts, click Container Registry.
In the left navigation, select <your-compartment-name>.
Click Create Repository.
Create a private repository with your choice of repo name:
```
<repo-name> = <repo-prefix>/<image-name>
```
Example: spring-projects/spring-boot-hello
You are now ready to push your local image to Container Registry.
Note

Before you push an image into a compartment, you must create a repository in that compartment.
Note

The slash in a repository name does not represent a hierarchical directory structure. The optional <repo-prefix> helps organize your repositories.

Push Your Local Image

Note

For MacOS, you can remove the sudo in the docker commands.

Open a terminal window.
Log in to OCI Container Registry:
```
sudo docker login <region-key>.ocir.io
```
You are prompted for your login name and password.
- Username: <tenancy-namespace>/<user-name>
- Password: <auth-token>
List your local Docker images:
```
sudo docker images
```
The Docker images on your system are displayed. Identify the image you created in the last section: spring-boot-hello
Tag your local image with the URL for the registry plus the repo name, so you can push it to that repo.
```
sudo docker tag <your-local-image> <repo-url>/<repo-name>
```
- Replace <repo-url>/<repo-name> with:
```
<region-key>.ocir.io/<tenancy-namespace>/<repo-name>
```
- Replace <repo-name> with:
  <repo-prefix>/<image-name> from the Create a Docker Repository section.
- Example:
```
sudo docker tag spring-boot-hello iad.ocir.io/my-namespace/spring-projects/spring-boot-hello
```
  In this example, the components are:
  - <repo-url>: iad.ocir.io/my-namespace/
  - <repo-name>: spring-projects/spring-boot-hello
Note

OCI Container Registry now supports creating a registry repo in any compartment rather than only in the root compartment (tenancy). To push the image to the repo you created, combine the registry URL with the exact repo name. OCI Container Registry matches the unique repo name and pushes your image.
Check your Docker images to see if the image is tagged.
```
sudo docker images
```
- The tagged image points to your local image and has the same image ID as your local image.
- The tagged image name is:
```
<region-key>.ocir.io/<tenancy-namespace>/<repo-prefix>/<image-name>
```

Push the image to Container Registry.

sudo docker push <tagged-image-name>:latest

Example:

sudo docker push iad.ocir.io/my-namespace/spring-projects/spring-boot-hello:latest

Open the navigation menu and click Developer Services. Under Containers & Artifacts, click Container Registry.
Find your image in Container Registry after the push command is complete.

Note

You can only push images that include the registry URL in their name.

Deploy the Image

With your image in Container Registry, you can now deploy your image and app.

Create a registry secret for your application. This secret authenticates your image when you deploy it to your cluster.
To create your secret, fill in the information in this template .
```
kubectl create secret docker-registry ocirsecret --docker-server=<region-key>.ocir.io  --docker-username='<tenancy-namespace>/<user-name>' --docker-password='<auth-token>'  --docker-email='<email-address>'
```
After the command runs, you get a message similar to: secret/ocirsecret created.
Verify that the secret is created. Issue the following command:
```
kubectl get secret ocirsecret --output=yaml
```
The output includes information about your secret in the yaml format.

Determine the host URL to your registry image using the following template:

<region-code>.ocir.io/<tenancy-namespace>/<repo-prefix>/<image-name>:<tag>

Example:

iad.ocir.io/my-namespace/spring-projects/spring-boot-hello:latest

On your system, create a file called sb-app.yaml with the following text:

Replace the following place holders:

<your-image-url>
<your-secret-name>

apiVersion: apps/v1
kind: Deployment
metadata:
  name: sbapp
spec:
  selector:
    matchLabels:
      app: sbapp
  replicas: 3
  template:
    metadata:
      labels:
        app: sbapp
    spec:
      containers:
      - name: sbapp
        image: <your-image-url>
        imagePullPolicy: Always
        ports:
        - name: sbapp
          containerPort: 8080
          protocol: TCP
      imagePullSecrets:
        - name: <your-secret-name>
---
apiVersion: v1
kind: Service
metadata:
  name: sbapp-lb
  labels:
    app: sbapp
  annotations:
    service.beta.kubernetes.io/oci-load-balancer-shape: "flexible"
    service.beta.kubernetes.io/oci-load-balancer-shape-flex-min: "10"
    service.beta.kubernetes.io/oci-load-balancer-shape-flex-max: "100"
spec:
  type: LoadBalancer
  ports:
  - port: 8080
  selector:
    app: sbapp

Deploy your application with the following command.
```
kubectl create -f sb-app.yaml
```
Output:
```
deployment.apps/sbapp created
```
Note

In the sb-app.yaml file, the code after the dashes adds a load balancer.

Test Your App

After you deploy your app, it might take the load balancer a few seconds to load.

Check if the load balancer is live:
```
kubectl get service
```
Repeat the command until load balancer is assigned a public IP address.
Use the load balancer IP address to connect to your app in a browser:
```
http://<load-balancer-IP-address>:8080
```
The browser displays: Spring Boot Hello World!
(Optional) To undeploy your application from the cluster, run the following command:
```
kubectl delete -f sb-app.yaml
```
Output:
```
deployment.apps "sbapp" deleted
service "sbapp-lb" deleted
```
Your application is now removed from your cluster.

What's Next

Congratulations! You have successfully created a Hello World application, deployed it to a Kubernetes cluster, and made it accessible on the internet, using the Spring Boot framework.

To explore more information about development with Oracle products, check out these sites:

Oracle Cloud Infrastructure Documentation

Kubernetes: Deploy a Spring Boot Application

Before You Begin 🔗

1. Prepare 🔗

2. Set Up a Cluster 🔗

3. Build a Local Application 🔗

4. Deploy Your Docker Image 🔗

What's Next 🔗

Before You Begin

1. Prepare

2. Set Up a Cluster

3. Build a Local Application

4. Deploy Your Docker Image

What's Next