Getting Started on Okteto Cloud with Go

Okteto Cloud gives instant access to secure Kubernetes namespaces to enable developers to code, build, and run Kubernetes applications entirely in the cloud.

This tutorial will show you how to develop and debug a Go sample application running in Okteto Cloud.

Prerequisites

• Install the latest version of the Okteto CLI. Follow this guide if you haven't done it yet.
• Configure access to your Okteto Cloud Namespace using the Okteto CLI or using the Okteto Cloud UI.

Step 1: Deploy the Go Sample App

Get a local version of the Go Sample App by executing the following commands:

$ git clone https://github.com/okteto/go-getting-started
$ cd go-getting-started

At the root of the directory, you'll find the okteto.yaml file. This describes how to build and deploy the Go Sample App.

build:
  hello-world:
    image: okteto.dev/go-hello-world:1.0.0
    context: .

deploy:
  - kubectl apply -f k8s.yml

Deploy your development environment by executing:

$ okteto deploy --build

 i  Using cindy @ cloud.okteto.com as context
 i  Building image for service 'hello-world'
 i  Building the image 'okteto.dev/go-hello-world:1.0.0' in tcp://buildkit.cloud.okteto.net:1234...
...
 ✓  Image 'registry.cloud.okteto.net/cindy/go-hello-world:1.0.0' successfully pushed
 i  Running kubectl apply -f k8s.yml
deployment.apps/hello-world created
service/hello-world created
ingress.networking.k8s.io/hello-world created
 ✓  Development environment 'go-getting-started' successfully deployed
 i  Run 'okteto up' to activate your development container

Log into Okteto Cloud and click on the URL of the application:

Did you notice that you're accessing your application through an HTTPs endpoint? This is because Okteto Cloud will automatically create them for you when you deploy your application. Cool no 😎?

Step 2: Activate your development container

The dev section defines how to activate a development container for the Go Sample App:

dev:
  hello-world:
    image: okteto/golang:1
    command: bash
    sync:
      - .:/usr/src/app
    volumes:
      - /go
      - /root/.cache
    securityContext:
      capabilities:
        add:
          - SYS_PTRACE
    forward:
      - 2345:2345

The hello-world key matches the name of the hello world Deployment. The meaning of the rest of fields is:

• 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.
• volumes: a list of paths in your development container to be mounted as persistent volumes. For example, this can be used to persist the Go cache.
• securityContext: SYS_PTRACE is a capability required by the Go debugger.
• forward: a list of ports to forward from your development container to locahost in your machine. This is needed to configure the Go debugger.

Also, note that there is a .stignore file to indicate which files shouldn't be synchronized to your development container. This is useful to avoid synchronizing binaries, build artifacts, git metadata, or dependencies like the vendor folder.

Next, execute the following command to activate your development container:

$ okteto up

 i  Using cindy @ cloud.okteto.com as context
 i  Development environment 'go-getting-started' already deployed.
 ✓  Images successfully pulled
 ✓  Files synchronized
    Context:   cloud.okteto.com
    Namespace: cindy
    Name:      hello-world
    Forward:   2345 -> 2345

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 4: Develop directly on Okteto Cloud

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 😎!

Step 5: Debug directly on Okteto Cloud

Okteto enables you to debug your applications directly from your favorite IDE. Let's take a look at how that works in VS Code, one of the most popular IDEs for Go development. If you haven't done it yet, install the Go extension available from Visual Studio marketplace.

Cancel the execution of go run main.go from the development container shell by pressing ctrl + c. Rerun your application in debug mode:

cindy:hello-world app> dlv debug --headless --listen=:2345 --log --api-version=2

API server listening at: [::]:2345
2019-10-17T14:39:24Z info layer=debugger launching process with args: [/usr/src/app/__debug_bin]

In your local machine, open VS Code, and install the Go extension.

The sample application is already configured for remote debugging. Open the Debug view in VS Code and run the Connect to okteto debug configuration (or just press the F5 shortcut) to start the remote debugger:

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Connect to okteto",
      "type": "go",
      "request": "attach",
      "mode": "remote",
      "remotePath": "/usr/src/app",
      "port": 2345,
      "host": "127.0.0.1"
    }
  ]
}

You should be replacing the value of remotePath with wherever your application code is.

Add a breakpoint on main.go, line 17. Go back to the browser, and reload the page. The execution will halt at your breakpoint. You can then inspect the request, the available variables, etc...

Your code is executing in Okteto Cloud, but you can debug it from your local machine without any extra services or tools. Pretty cool no? 😉

Next steps

Congratulations, you just developed your first application in Okteto Cloud 🚀.

Okteto lets you develop your applications directly on Kubernetes. This way you can:

• Eliminate integration issues by developing in a realistic environment
• Test your application end to end as fast as you type code
• No more CPU cycles wasted in your machine. Develop at the speed of the cloud!

Find more advanced samples with Okteto in this repository or join our community to ask questions and share your feedback.