Run your first Hello World program with score-helm

Run your first Score implementation with a Hello World application for score-helm.

Overview

The primary goal of the Score file is to quickly and easily describe how to compose and run Workloads. The following covers what you need to know to compose a Score file and run an application.

Building blocks

At it’s core, the Score file needs a name and a container to run.

In the following example, the Score tab shows the minimum configuration needed to run a Workload and the Docker Compose tab shows the output of the score-helm run command.

The score.yaml file contains a Workload named hello-world and specifies a container image for Docker as busybox.

The following is the minimum configuration needed to run a Workload.

apiVersion: score.dev/v1b1
metadata:
  name: hello-world

containers:
  container-id:
    image: busybox

The output of score-helm run -f ./score.yaml -o ./values.yaml.

containers:
  container-id:
    image:
      name: busybox

The following is a description of the previous command.

  • run tells the CLI to translate the Score file to a Helm values.yaml file.
  • -f is the path to the Score file.
  • -o specifies the path to the values.yaml file.

In the next step, you’ll want to think about how to specify resources for your container.

Containers

In the following example, we’ll create a simple service based on busybox using the containers definition.

apiVersion: score.dev/v1b1

metadata:
  name: hello-world

containers:
  hello:
    image: busybox
    command: ["/bin/sh"]
    args: ["-c", "while true; do echo Hello World!; sleep 5; done"]

The output of score-helm run -f ./score.yaml -o ./values.yaml.

containers:
  hello:
    args:
      - -c
      - while true; do echo Hello World!; sleep 5; done
    command:
      - /bin/sh
    image:
      name: busybox

Deploy to Helm

The following steps are specific to deploying to Helm.

Create values.yaml template

Now that the values.yaml file is ready, create a generic values template.

helm create -p /examples/values.yaml hello

Deploy Helm file

Run the following command to deploy the Helm values.yaml file.

helm install --values ./values.yaml hello ./hello

The following are the outputs of the previous command.

NAME: hello
LAST DEPLOYED: Thu Nov  01 00:00:00 2022
NAMESPACE: default
STATUS: deployed
REVISION: 1
TEST SUITE: None
# Source: hello/templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: hello
  labels:
    helm.sh/chart: hello-0.1.0
    app.kubernetes.io/name:
    app.kubernetes.io/instance: hello
    app.kubernetes.io/version: "0.1.0"
    app.kubernetes.io/managed-by: Helm
spec:
  selector:
    matchLabels:
      app.kubernetes.io/name:
      app.kubernetes.io/instance: hello
  template:
    metadata:
      labels:
        app.kubernetes.io/name:
        app.kubernetes.io/instance: hello
    spec:
      containers:
        - name: hello
          image: "busybox"
          command:
            - /bin/sh
          args:
            - -c
            - while true; do echo Hello World!; sleep 5; done

Results You’ve successfully created a Hello World application in Score and created a deployment.yaml file for Kubernetes.