Containerization
How to use Docker, Kubernetes, and Helm Charts to deploy your VLINGO XOOM platform services.
The following shows how to set up a Reactive, scalable, event-driven application based for VLINGO XOOM, being deployed on Kubernetes and packaged by Helm Chart.
First, we need a project structure that allows us to start building our application. That's when XOOM Designer comes to play. It saves a lot of effort providing a web/graphical user interface to generate initial development resources such as application files, directory structure,
Dockerfile
and much more. Once it is installed, you can use the project generator wizard running the following command: $ ./xoom gui
This command will open your preferred browser. Just fill in the wizard steps so the project will be generated and ready to start the development.
If you choose either Docker or Kubernetes on the deployment step, a
Dockerfile
will be placed in the root folder:FROM adoptopenjdk/openjdk11-openj9:jdk-11.0.1.13-alpine-slim
COPY target/xoom-example-*.jar xoom-example.jar
EXPOSE 8080
CMD java -Dcom.sun.management.jmxremote -noverify ${JAVA_OPTS} -jar xoom-example.jar
That means the image is ready to be built along with the executable
jar
. Both tasks are performed through a single Starter CLI command:$ ./xoom docker package
$ ./xoom docker push
You can find more information on
xoom docker push
and other containerization shortcut commands here.The previous steps are pretty similar for a VLINGO XOOM service or application without VLINGO XOOM. The executable
jar
, including the dependency jars, can be generated with the following plugin configuration:<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<version>1.6.0</version>
<executions>
<execution>
<goals>
<goal>java</goal>
</goals>
</execution>
</executions>
<configuration>
<mainClass>io.vlingo.xoom.app.infra.Bootstrap</mainClass>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
<configuration>
<finalName>vlingo-xoom-app</finalName>
<descriptors>
<descriptor>assembly.xml</descriptor>
</descriptors>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>io.vlingo.xoom.app.infra.Bootstrap</mainClass>
<classpathPrefix>dependency-jars/</classpathPrefix>
</manifest>
</archive>
</configuration>
</plugin>
The
Dockerfile
requires the jar
with dependencies:FROM adoptopenjdk/openjdk11-openj9:jdk-11.0.1.13-alpine-slim
COPY target/vlingo-xoom-app-withdeps.jar vlingo-xoom-app.jar
EXPOSE 8082
CMD java -Dcom.sun.management.jmxremote -noverify ${JAVA_OPTS} -jar vlingo-xoom-app.jar
Now, besides the application itself, the Docker image is ready to be built and published:
$ ./mvn clean package && docker build ./ -t vlingo-xoom-app:latest
$ ./docker tag vlingo-xoom-app:latest [publisher]/vlingo-xoom-app:latest
$ ./docker push [publisher]/vlingo-xoom-app
Kubernetes is the chosen tool for container orchestration. In this scenario, it will run a single node cluster serving the VLINGO XOOM application. Whereas
kubeadm
is installed, the cluster initialization is showed below:$ ./sudo kubeadm init --pod-network-cidr=192.168.0.0/16
Secondly, the settings folder should be mapped:
$ ./mkdir -p $HOME/.kube
$ ./sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
$ ./sudo chown $(id -u):$(id -g) $HOME/.kube/config
Kubernetes supports multiple networking model implementations. For now, we choose Calico. Its network policy configuration file can be added using
kubectl
, the command line tool for controlling Kubernetes clusters:$ ./kubectl apply -f https://docs.projectcalico.org/manifests/calico.yaml
Considering the single node cluster is the option for this example, the last step is to prepare the master node by removing taints which, in short, prevents a deployable unit (Pods) to run on it.
$ ./kubectl taint nodes --all node-role.kubernetes.io/master-
At this point, we need to tell Kubernetes what is the application desired state and how we want to expose our services, number of replicas, allocated resources... The simpler way is through Helm, a special tool for Kubernetes application management. It simplifies installation, upgrade, scaling and other common tasks. Getting started, let's create a chart, which is a collection of files inside of a directory. This is how it's made:
$ ./helm create xoom-example
The output looks like the following structure:
xoom-example/
Chart.yaml # A YAML file containing information about the chart
LICENSE # OPTIONAL: A plain text file containing the license for the chart
README.md # OPTIONAL: A human-readable README file
values.yaml # The default configuration values for this chart
values.schema.json # OPTIONAL: A JSON Schema for imposing a structure on the values.yaml file
charts/ # A directory containing any charts upon which this chart depends.
crds/ # Custom Resource Definitions
templates/ # A directory of templates that, when combined with values,
# will generate valid Kubernetes manifest files.
templates/NOTES.txt # OPTIONAL: A plain text file containing short usage notes
In this basic scenario, all we need to do is editing
values.yaml
, informing the Docker image repository, service type / port and number of replicas:# Default values for xoom-example.
# This is a YAML-formatted file.
# Declare variables to be passed into your templates.
replicaCount: 3
image:
repository: [publisher]/xoom-example
...
service:
type: ClusterIP
port: 8080
Using
lint
, we can check if the chart is well-formed after the addition:$ ./helm lint xoom-example
==> Linting xoom-example
[INFO] Chart.yaml: icon is recommended
1 chart(s) linted, 0 chart(s) failed
With
template
command, we can see all files that Helm will generate and install into Kubernetes: # Source: xoom-example/templates/serviceaccount.yaml
apiVersion: v1
kind: ServiceAccount
metadata:
name: RELEASE-NAME-xoom-example
labels:
helm.sh/chart: xoom-example-0.1.0
app.kubernetes.io/name: xoom-example
app.kubernetes.io/instance: RELEASE-NAME
app.kubernetes.io/version: "1.16.0"
app.kubernetes.io/managed-by: Helm
---
# Source: xoom-example/templates/service.yaml
apiVersion: v1
kind: Service
metadata:
name: RELEASE-NAME-xoom-example
labels:
helm.sh/chart: xoom-example-0.1.0
app.kubernetes.io/name: xoom-example
app.kubernetes.io/instance: RELEASE-NAME
app.kubernetes.io/version: "1.16.0"
app.kubernetes.io/managed-by: Helm
spec:
type: ClusterIP
ports:
- port: 8080
targetPort: http
protocol: TCP
name: http
selector:
app.kubernetes.io/name: xoom-example
app.kubernetes.io/instance: RELEASE-NAME
---
# Source: xoom-example/templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: RELEASE-NAME-xoom-example
labels:
helm.sh/chart: xoom-example-0.1.0
app.kubernetes.io/name: xoom-example
app.kubernetes.io/instance: RELEASE-NAME
app.kubernetes.io/version: "1.16.0"
app.kubernetes.io/managed-by: Helm
spec:
replicas: 3
selector:
matchLabels:
app.kubernetes.io/name: xoom-example
app.kubernetes.io/instance: RELEASE-NAME
template:
metadata:
labels:
app.kubernetes.io/name: xoom-example
app.kubernetes.io/instance: RELEASE-NAME
spec:
serviceAccountName: RELEASE-NAME-xoom-example
securityContext:
{}
containers:
- name: xoom-example
securityContext:
{}
image: "xoom-example:1.16.0"
imagePullPolicy: IfNotPresent
ports:
- name: http
containerPort: 8080
protocol: TCP
livenessProbe:
httpGet:
path: /
port: http
readinessProbe:
httpGet:
path: /
port: http
resources:
{}
---
# Source: xoom-example/templates/tests/test-connection.yaml
apiVersion: v1
kind: Pod
metadata:
name: "RELEASE-NAME-xoom-example-test-connection"
labels:
helm.sh/chart: xoom-example-0.1.0
app.kubernetes.io/name: xoom-example
app.kubernetes.io/instance: RELEASE-NAME
app.kubernetes.io/version: "1.16.0"
app.kubernetes.io/managed-by: Helm
annotations:
"helm.sh/hook": test-success
spec:
containers:
- name: wget
image: busybox
command: ['wget']
args: ['RELEASE-NAME-xoom-example:8080']
restartPolicy: Never
We finish the deployment step executing the
install
command:$ ./helm install xoom-example
A new Pod is created by Kubernetes to hold the
xoom-example
app. You should check if it's running fine:$ ./kubectl get pods
NAME READY STATUS RESTARTS AGE
xoom-example-765bf4c7b4-26z48 1/1 Running 0 64s
Also, it is recommended to check the application logs:
$ ./kubectl logs xoom-example-765bf4c7b4-26z48
Helm also supports a packaging and versioning mechanism, that is, a set of commands that allows us to package the Chart structure and files to make it collaborative. First, an
index.yaml
file should be created based on a Git repository, that will be the chart repository:$ ./helm repo index chart-repo/ --url https://<username>.github.io/chart-repo
Next, the remote repository is added:
$ ./helm repo add chart-repo https://<username>.github.io/chart-repo
At last, enable the chart installation from the repository:
$ ./helm install my-repo/hello-world --name=hello-world
Find a complete code example on GitHub, built on a DDD microservices architecture, combining Kubernetes, Helm Chart and VLINGO XOOM.
Last modified 10mo ago