In this chapter, we will create a new basic Spring Boot app. It will get some new functionality with each new chapter, eventually resembling the real-life app that incorporates the best practices for organizing applications and CI/CD with werf.

Preparing the environment

Prepare the environment using the instructions provided in the “Preparing the environment” chapter (if you have not done this already).

Please, refer to these helpful resources if the environment has stopped working or instructions in this chapter don’t work:

Is Docker running?

Let’s launch Docker Desktop. It takes some time for this application to start Docker. If there are no errors during the startup process, check that Docker is running and is properly configured:

docker run hello-world

You will see the following output if the command completes successfully:

Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
b8dfde127a29: Pull complete
Digest: sha256:9f6ad537c5132bcce57f7a0a20e317228d382c3cd61edae14650eec68b2b345c
Status: Downloaded newer image for hello-world:latest

Hello from Docker!
This message shows that your installation appears to be working correctly.

Should you have any problems, please refer to the Docker documentation.

Let’s launch the Docker Desktop application. It takes some time for the application to start Docker. If there are no errors during the startup process, then check that Docker is running and is properly configured:

docker run hello-world

You will see the following output if the command completes successfully:

Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
b8dfde127a29: Pull complete
Digest: sha256:9f6ad537c5132bcce57f7a0a20e317228d382c3cd61edae14650eec68b2b345c
Status: Downloaded newer image for hello-world:latest

Hello from Docker!
This message shows that your installation appears to be working correctly.

Should you have any problems, please refer to the Docker documentation.

Start Docker:

sudo systemctl restart docker

Make sure that Docker is running:

sudo systemctl status docker

If the Docker start is successful, you will see the following output:

● docker.service - Docker Application Container Engine
     Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: enabled)
     Active: active (running) since Thu 2021-06-24 13:05:17 MSK; 13s ago
TriggeredBy: ● docker.socket
       Docs: https://docs.docker.com
   Main PID: 2013888 (dockerd)
      Tasks: 36
     Memory: 100.3M
     CGroup: /system.slice/docker.service
             └─2013888 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock

dockerd[2013888]: time="2021-06-24T13:05:16.936197880+03:00" level=warning msg="Your kernel does not support CPU realtime scheduler"
dockerd[2013888]: time="2021-06-24T13:05:16.936219851+03:00" level=warning msg="Your kernel does not support cgroup blkio weight"
dockerd[2013888]: time="2021-06-24T13:05:16.936224976+03:00" level=warning msg="Your kernel does not support cgroup blkio weight_device"
dockerd[2013888]: time="2021-06-24T13:05:16.936311001+03:00" level=info msg="Loading containers: start."
dockerd[2013888]: time="2021-06-24T13:05:17.119938367+03:00" level=info msg="Loading containers: done."
dockerd[2013888]: time="2021-06-24T13:05:17.134054120+03:00" level=info msg="Daemon has completed initialization"
systemd[1]: Started Docker Application Container Engine.
dockerd[2013888]: time="2021-06-24T13:05:17.148493957+03:00" level=info msg="API listen on /run/docker.sock"

Now let’s check if Docker is available and its configuration is correct:

docker run hello-world

You will see the following output if the command completes successfully:

Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
b8dfde127a29: Pull complete
Digest: sha256:9f6ad537c5132bcce57f7a0a20e317228d382c3cd61edae14650eec68b2b345c
Status: Downloaded newer image for hello-world:latest

Hello from Docker!
This message shows that your installation appears to be working correctly.

Should you have any problems, please refer to the Docker documentation.

Have you restarted the computer after setting up the environment?

Let’s start the minikube cluster we have already configured in the “Preparing the environment” chapter:

minikube start

Set the default Namespace so that you don’t have to specify it every time you invoke kubectl:

kubectl config set-context minikube --namespace=werf-guide-app

You will see the following output if the command completes successfully:

😄  minikube v1.20.0 on Ubuntu 20.04
✨  Using the docker driver based on existing profile
👍  Starting control plane node minikube in cluster minikube
🚜  Pulling base image ...
🎉  minikube 1.21.0 is available! Download it: https://github.com/kubernetes/minikube/releases/tag/v1.21.0
💡  To disable this notice, run: 'minikube config set WantUpdateNotification false'

🔄  Restarting existing docker container for "minikube" ...
🐳  Preparing Kubernetes v1.20.2 on Docker 20.10.6 ...
🔎  Verifying Kubernetes components...
    ▪ Using image gcr.io/google_containers/kube-registry-proxy:0.4
    ▪ Using image k8s.gcr.io/ingress-nginx/controller:v0.44.0
    ▪ Using image registry:2.7.1
    ▪ Using image docker.io/jettech/kube-webhook-certgen:v1.5.1
    ▪ Using image docker.io/jettech/kube-webhook-certgen:v1.5.1
    ▪ Using image gcr.io/k8s-minikube/storage-provisioner:v5
🔎  Verifying registry addon...
🔎  Verifying ingress addon...
🌟  Enabled addons: storage-provisioner, registry, default-storageclass, ingress
🏄  Done! kubectl is now configured to use "minikube" cluster and "werf-guide-app" namespace by default

Make sure that the command output contains the following line:

Restarting existing docker container for "minikube"

Its absence means that a new minikube cluster was created instead of using the old one. In this case, repeat all the steps required to install the environment using minikube.

Now run the command in the background PowerShell terminal (do not close its window):

minikube tunnel --cleanup=true

Let’s start the minikube cluster we have already configured in the “Preparing the environment” chapter:

minikube start --namespace werf-guide-app

Set the default Namespace so that you don’t have to specify it every time you invoke kubectl:

kubectl config set-context minikube --namespace=werf-guide-app

You will see the following output if the command completes successfully:

😄  minikube v1.20.0 on Ubuntu 20.04
✨  Using the docker driver based on existing profile
👍  Starting control plane node minikube in cluster minikube
🚜  Pulling base image ...
🎉  minikube 1.21.0 is available! Download it: https://github.com/kubernetes/minikube/releases/tag/v1.21.0
💡  To disable this notice, run: 'minikube config set WantUpdateNotification false'

🔄  Restarting existing docker container for "minikube" ...
🐳  Preparing Kubernetes v1.20.2 on Docker 20.10.6 ...
🔎  Verifying Kubernetes components...
    ▪ Using image gcr.io/google_containers/kube-registry-proxy:0.4
    ▪ Using image k8s.gcr.io/ingress-nginx/controller:v0.44.0
    ▪ Using image registry:2.7.1
    ▪ Using image docker.io/jettech/kube-webhook-certgen:v1.5.1
    ▪ Using image docker.io/jettech/kube-webhook-certgen:v1.5.1
    ▪ Using image gcr.io/k8s-minikube/storage-provisioner:v5
🔎  Verifying registry addon...
🔎  Verifying ingress addon...
🌟  Enabled addons: storage-provisioner, registry, default-storageclass, ingress
🏄  Done! kubectl is now configured to use "minikube" cluster and "werf-guide-app" namespace by default

Make sure that the command output contains the following line:

Restarting existing docker container for "minikube"

Its absence means that a new minikube cluster was created instead of using the old one. In this case, repeat all the steps required to install the environment from scratch using minikube.

Did you accidentally delete the application's Namespace?

If you have inadvertently deleted Namespace of the application, you must run the following commands to proceed with the guide:

kubectl create namespace werf-guide-app
kubectl create secret docker-registry registrysecret \
  --docker-server='https://index.docker.io/v1/' \
  --docker-username='<Docker Hub username>' \
  --docker-password='<Docker Hub password>'

You will see the following output if the command completes successfully:

namespace/werf-guide-app created
secret/registrysecret created
Nothing helps; the environment or instructions keep failing.

If nothing worked, repeat all the steps described in the “Preparing the environment” chapter and create a new environment from scratch. If creating an environment from scratch did not help either, please, tell us about your problem in our Telegram chat or create an issue on GitHub. We will be happy to help you!

Preparing the repository

Update the existing repository containing the application:

Run the following commands in PowerShell:

cd ~/werf-guide/app

# To see what changes we will make later in this chapter, let's replace all the application files
# in the repository with new, modified files containing the changes described below.
git rm -r .
cp -Recurse -Force ~/werf-guide/guides/examples/java_springboot/010_basic_app/* .
git add .
git commit -m WIP
What changes we will make
# Enter the command below to show the files we are going to change.
git show --stat
# Enter the command below to show the changes that will be made.
git show

Run the following commands in Bash:

cd ~/werf-guide/app

# To see what changes we will make later in this chapter, let's replace all the application files
# in the repository with new, modified files containing the changes described below.
git rm -r .
cp -rf ~/werf-guide/guides/examples/java_springboot/010_basic_app/. .
git add .
git commit -m WIP
What changes we will make
# Enter the command below to show files we are going to change.
git show --stat
# Enter the command below to show the changes that will be made.
git show

Doesn’t work? Try the instructions on the “I am just starting from this chapter” tab above.

Prepare a new repository with the application:

Run the following commands in PowerShell:

# Clone the example repository to ~/werf-guide/guides (if you have not cloned it yet).
if (-not (Test-Path ~/werf-guide/guides)) {
  git clone https://github.com/werf/werf-guides $env:HOMEPATH/werf-guide/guides
}

# Copy the (unchanged) application files to ~/werf-guide/app.
rm -Recurse -Force ~/werf-guide/app
cp -Recurse -Force ~/werf-guide/guides/examples/basic/004_modify_app ~/werf-guide/app

# Make the ~/werf-guide/app directory a git repository.
cd ~/werf-guide/app
git init
git add .
git commit -m initial

# To see what changes we will make later in this chapter, let's replace all the application files
# in the repository with new, modified files containing the changes described below.
git rm -r .
cp -Recurse -Force ~/werf-guide/guides/examples/java_springboot/010_basic_app/* .
git add .
git commit -m WIP
What changes we will make
# Enter the command below to show the files we are going to change.
git show --stat
# Enter the command below to show the changes that will be made.
git show

Run the following commands in Bash:

# Clone the example repository to ~/werf-guide/guides (if you have not cloned it yet).
test -e ~/werf-guide/guides || git clone https://github.com/werf/werf-guides ~/werf-guide/guides

# Copy the (unchanged) application files to ~/werf-guide/app.
rm -rf ~/werf-guide/app
cp -rf ~/werf-guide/guides/examples/basic/004_modify_app ~/werf-guide/app

# Make the ~/werf-guide/app directory a git repository.
cd ~/werf-guide/app
git init
git add .
git commit -m initial

# To see what changes we will make later in this chapter, let's replace all the application files
# in the repository with new, modified files containing the changes described below.
git rm -r .
cp -rf ~/werf-guide/guides/examples/java_springboot/010_basic_app/. .
git add .
git commit -m WIP
What changes we will make
# Enter the command below to show files we are going to change.
git show --stat
# Enter the command below to show the changes that will be made.
git show

A new Spring Boot application

In this chapter, we will use a new basic Spring Boot application with the same feature set as the application from the previous section.

We got it like this - generated the directory structure for our Spring Boot.

To do this, we used start.spring.io and created an application template with the following parameters:

  • Maven project — Maven is used as the project build automation tool;
  • Spring Boot version — 2.6.1;
  • Language — select Java as the development language;
  • Java version — 11;
  • Package format — *.jar;
  • Select Spring Web in the dependencies (it is required for a RESTful service).

This application doesn’t have any functionality that is not needed at this stage. The only thing left is the configuration for the production environment.

Then, a new /ping route has been added to the API:

The ping method of the standard controller will handle this route (and return the pong string): Then we added a new controller that returns pong for requests sent to the /ping endpoint.

package io.werf.werfguidesapp.controllers;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class PingController {
	
	@GetMapping("/ping")
	public String Ping() {
		return "pong\n";
	}
}
package io.werf.werfguidesapp.controllers; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RestController; @RestController public class PingController { @GetMapping("/ping") public String Ping() { return "pong\n"; } }

As for the building and CI/CD, the most significant changes affected the image build process:

# Here, a multi-stage build is used to assemble the image
# The image to build the project
FROM eclipse-temurin:11-alpine AS builder
# Copy the source code of the application.
COPY . /src
WORKDIR /src
# Run Maven to build the project.
RUN ./mvnw clean package

# The image to deploy to the cluster.
FROM eclipse-temurin:11-alpine
WORKDIR /app
# Copy the project executable from the build image.
COPY --from=builder /src/target/*.jar ./app.jar
EXPOSE 8080
ENTRYPOINT ["java","-jar","./app.jar"]
# Here, a multi-stage build is used to assemble the image # The image to build the project FROM eclipse-temurin:11-alpine AS builder # Copy the source code of the application. COPY . /src WORKDIR /src # Run Maven to build the project. RUN ./mvnw clean package # The image to deploy to the cluster. FROM eclipse-temurin:11-alpine WORKDIR /app # Copy the project executable from the build image. COPY --from=builder /src/target/*.jar ./app.jar EXPOSE 8080 ENTRYPOINT ["java","-jar","./app.jar"]

… while CI/CD changes were minimal. For example, here is the Deployment of the new application:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: werf-guide-app
spec:
  replicas: 1
  selector:
    matchLabels:
      app: werf-guide-app
  template:
    metadata:
      labels:
        app: werf-guide-app
    spec:
      imagePullSecrets:
      - name: registrysecret
      containers:
      - name: app
        image: {{ .Values.werf.image.app }}
        ports:
        - containerPort: 8080
apiVersion: apps/v1 kind: Deployment metadata: name: werf-guide-app spec: replicas: 1 selector: matchLabels: app: werf-guide-app template: metadata: labels: app: werf-guide-app spec: imagePullSecrets: - name: registrysecret containers: - name: app image: {{ .Values.werf.image.app }} ports: - containerPort: 8080

Our current application is stateless and does not need a database to run. We will show you how to turn it into a stateful application and deploy a dedicated database in the following chapters.

Deploying a new application

Let’s check if the new application is running fine by deploying it to the Kubernetes cluster:

werf converge --repo <DOCKER HUB USERNAME>/werf-guide-app

You should see the following output:

┌ ⛵ image app
│ Use cache image for app/dockerfile
│      name: <DOCKER HUB USERNAME>/werf-guide-app:899de306512df27111bab8676adc0bade21f5dbcf02613c42611d5f4-1639997041437
│        id: 202e8932de50
│   created: 2021-12-20 13:44:00 +0300 MSK
│      size: 208.8 MiB
└ ⛵ image app (1.27 seconds)

┌ Waiting for release resources to become ready
│ ┌ Status progress
│ │ DEPLOYMENT                                                                                                  REPLICAS            AVAILABLE             UP-TO-DATE                           
│ │ werf-guide-app                                                                                              2->1/1              1                     1                                    
│ │ │   POD                                      READY          RESTARTS            STATUS                                                                                                     
│ │ ├── guide-app-6d5db67c9f-k6lhd               1/1            1                   Running -> Terminating      
│ │ └── guide-app-7656c9f878-kkmlt               1/1            0                   ContainerCreating ->        
│ │                                                                                 Running                     
│ └ Status progress
└ Waiting for release resources to become ready (18.42 seconds)

Release "werf-guide-app" has been upgraded. Happy Helming!
NAME: werf-guide-app
LAST DEPLOYED: Mon Dec 20 13:52:00 2021
NAMESPACE: werf-guide-app
STATUS: deployed
REVISION: 6
TEST SUITE: None
Running time 21.96 seconds

Let’s check whether our application works:

curl http://werf-guide-app.test/ping

You should see the following response:

pong
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