Getting started with Okteto

This tutorial provides a step by step guide to configure an Okteto Manifest.

Overview

The tutorial is composed of the following steps:

• Step 1: Code the Hello World application
• Step 2: Define a Dockerfile for building the Docker image of the Hello World application
• Step 3: Create Kubernetes manifests to deploy the Hello World application on Okteto
• Step 4: Generate your Okteto Manifest
• Step 5: Deploy your Development Environment
• Step 6: Configure a Remote Development Container
• Step 7: Develop on your Remote Development Container

Let's get started!

Step 1: Code the Hello World application

We will use a simple Hello World application to illustrate how to configure an Okteto Manifest. The Hello World application is a simple web service that responds "Hello World!" to every request. It's written in Go, but Okteto can be used with any application that runs on Kubernetes.

First, make a new directory called hello-world and move inside it:

mkdir hello-world
cd hello-world

Create a new file under the name main.go with the following content:

package main

import (
    "fmt"
    "net/http"
)

func main() {
    fmt.Println("Starting hello-world server...")
    http.HandleFunc("/", helloServer)
    if err := http.ListenAndServe(":8080", nil); err != nil {
        panic(err)
    }
}

func helloServer(w http.ResponseWriter, r *http.Request) {
    fmt.Fprint(w, "Hello world!")
}

main.go implements a Golang web server that listens on port 8080 and responds to every Http request with the message Hello world!

Next, initialize your go module running the following command:

go mod init go-getting-started

Step 2: Define a Dockerfile for building the Docker image of the Hello World application

You need to build a Docker image and push it to a Docker registry before Okteto can run your application.

To do that, you need to define a Dockerfile. A Dockerfile file is a sequence of instructions to build the Docker image of your application. If you're not familiar with Docker, we strongly recommend you learn about it.

Open a new file under the name Dockerfile with the following content:

FROM golang:buster

WORKDIR /app
ADD . .
RUN go build -o app

EXPOSE 8080
CMD ["./app"]

Step 3: Create Kubernetes manifests to deploy the Hello World application on Okteto

To deploy an application to Okteto, you need to define it using Kubernetes manifests.

Let's start by creating a new folder for the Kubernetes manifests:

mkdir k8s

When you use a Kubernetes manifest, you tell Kubernetes how you want your application to run. This time, you'll create a deployment object. Create a new file k8s/deployment.yaml with the following content:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: hello-world
spec:
  selector:
    matchLabels:
      app: hello-world
  replicas: 1
  template:
    metadata:
      labels:
        app: hello-world
    spec:
      containers:
      - name: hello-world
        image: okteto.dev/hello-world:latest
        ports:
        - containerPort: 8080

The deployment manifest has three main sections:

• metadata defines the name for your deployment.
• replicas defines how many copies of it you want running.
• template tells Kubernetes what to deploy, and what labels to add. In this case, a single container, with the okteto.dev/hello-world:latest image we will build in our Okteto Pipeline, listening on port 8080, and with the app: hello-world label. Note that this label is the same used in the selector section.

tip

If you want to know more about Kubernetes deployment objects, check the official docs.

You'll now need a way to access your application. You can expose an application on Kubernetes by creating a service object. Create a new file called k8s/service.yaml with the following content:

apiVersion: v1
kind: Service
metadata:
  name: hello-world
spec:
  type: LoadBalancer
  ports:
    - name: http
      port: 8080
  selector:
    app: hello-world

The service manifest has four main sections:

• metadata tells Kubernetes how to name your service
• type tells Kubernetes how you want to expose your service. In this case, it will expose it externally through a Load Balancer. In you want to expose your application using ingress, check the docs.
• ports tells Kubernetes which ports you want to expose
• selector tells Kubernetes how to direct traffic. In this case, any pod with the app: hello-world label will receive traffic.

tip

Kubernetes manifests can get complex to manage. As your application grows, we recommend you pack your application using Helm.

You now have everything ready to define the Okteto Manifest of the Hello World application.

Step 4: Generate your Okteto Manifest

You can automate the deployment of the Hello World application with an Okteto Manifest to provide a one-click deployment experience for anyone in your team or your open source community. To define your Okteto Manifest, create a new file okteto.yaml with the following content:

build:
  hello-world:
     image: okteto.dev/hello-world:latest
     context: .
     dockerfile: Dockerfile
deploy:
  - kubectl apply -f k8s

The Okteto Manifest has a build section to define how to build the image of my application.

The Okteto Manifest also has a deploy section to define the sequence of commands to deploy the Hello World application. In this case, it deploys the Hello World application using kubectl and the Kubernetes manifests you created on Step 2.

You can make use of tools such as kubectl, helm, okteto, and kustomize in your deploy commands.

Step 5: Deploy your Development Environment

Install the Okteto CLI and configure access to Okteto:

okteto context use https://okteto.example.com

 ✓  Using context cindy @ okteto.example.com

In order to deploy your application, run the following command:

okteto deploy

 i  Using cindy @ okteto.example.com as context
 i  Images were already built. To rebuild your images run 'okteto build' or 'okteto deploy --build'
 ✓  kubectl apply -f k8s
 i  Endpoints available:
  - https://hello-world-cindy.okteto.example.com/
 ✓  Development environment 'go-getting-started' successfully deployed

and that's all, your application will be built and deployed in seconds!

Step 6: Configure a Remote Development Container

Building and deploying your application for each code change can be tedious. In prevent that, you can configure how to live update your application while you are coding defining a development container.

To do that, add the following content to your Okteto Manifest:

dev:
  hello-world:
    image: okteto/golang:1
    command: bash
    sync:
      - .:/usr/src/app

This is the meaning of the fields we are using here:

• image: the image used by the development container. More information on development images here.
• command: the start command of the development container.
• sync: the folders that will be synchronized between your local machine and the development container.

Now execute the following command to activate your development container:

okteto up

 ✓  Persistent volume successfully attached
 ✓  Images successfully pulled
 ✓  Files synchronized
    Namespace: cindy
    Name:      hello-world

Welcome to your development container. Happy coding!
cindy:hello-world app>

Working in your development container is the same as working on your local machine. Start the application by running the following command:

cindy:hello-world app> go run main.go

Starting hello-world server...

Go back to the browser, and reload the page to test that your application is running.

Step 7: Develop on your Remote Development Container

Open the file main.go in your favorite local IDE and modify the response message on line 17 to be Hello world from Okteto!. Save your changes.

func helloServer(w http.ResponseWriter, r *http.Request) {
	fmt.Fprint(w, "Hello world from Okteto!")
}

Okteto will synchronize your changes to your development container. Cancel the execution of go run main.go from the development container shell by pressing ctrl + c. Rerun your application:

cindy:hello-world app> go run main.go

Starting hello-world server...

Go back to the browser and reload the page. Your code changes were instantly applied. No commit, build, or push required 😎!

Next steps

Congratulations, you just configured your first Okteto Manifest 🚀

Head over to our getting started guides to see how to configure Okteto to live-update your application with different programming languages and debuggers.