Validate Your Configurations in skaffold Workflow

<walkthrough-disable-features toc></walkthrough-disable-features>

Introduction

What is kpt?

Kpt is an OSS tool for Kubernetes packaging, which uses a standard format to bundle, publish, customize, update, and apply configuration manifests.

What kpt can help you with

You will get an hands-on off-the-shelf experience about the GitOps CI/CD workflow in skaffold.
You can validate each of your config changes declaratively.
You won't encounter version conflict if the config hydration (a.k.a kustomize) mismatch with the deployment tool (e.g. kubectl).
You can prune your resources accurately with a three-way merge strategy.

What you'll learn

How to add a validation to your config changes.
How to define validation rules in the form of a declarative configuration.
How to use the validation in kustomized resources.

Prerequisites

If you are new to skaffold, you can check out the skaffold tutorials to get a basic idea. Or just follow this codelab, we will explain what happens in each step.

Install `skaffold`

Check if skaffold is installed and the installed version is >= v1.17.0
bash
```
skaffold version
```

If you haven't installed skaffold previously, run

bash

curl -Lo skaffold https://storage.googleapis.com/skaffold/builds/latest/skaffold-linux-amd64 && \
sudo install skaffold /usr/bin/ | bash

To upgrade skaffold to a newer version, run

bash

sudo rm -f /usr/bin/skaffold && curl -Lo skaffold https://storage.googleapis.com/skaffold/builds/latest/skaffold-linux-amd64 && \
sudo install skaffold /usr/bin/ | bash

Install `kpt`

Check if kpt is installed and the installed version is >= 0.34.0
bash
```
kpt version
```
If you haven't installed kpt previously, run
bash
```
sudo apt-get install google-cloud-sdk-kpt
```

Install `kustomize`

Check if kustomize is installed and the installed version is >= v3.4.3
bash
```
kustomize version
```

If you haven't installed kustomize previously, run

bash

curl -s "https://raw.githubusercontent.com/kubernetes-sigs/kustomize/master/hack/install_kustomize.sh"  | bash &&  sudo mv kustomize /usr/local/go/bin

Getting started

Time to complete: About 3 minutes

In your <walkthrough-editor-spotlight spotlightId="menu-terminal-new-terminal">terminal</walkthrough-editor-spotlight>, run this command to start your local minikube cluster:
bash
```
minikube start
```
Once your cluster is set up, the following message is displayed:
terminal
```
Done! kubectl is now configured to use "minikube"
```

Now let's use kpt pkg to download the application example.

bash

kpt pkg get https://github.com/GoogleContainerTools/skaffold.git/codelab/01_kpt-validate/resources/sample-app guestbook-cl && cd guestbook-cl

<walkthrough-pin-section-icon></walkthrough-pin-section-icon> Extended Reading

kpt pkg downloads the resource from a remote repository, a branch or a subdirectory. It does not contain the git version control history but only the specific git reference, so you can compose your own "package" from multiple repositories.

Read more about the kpt package from here

Taking a deeper look at the skaffold.yaml

Time to complete: About 3 minutes

The example has already configured the <walkthrough-editor-open-file filePath="guestbook-cl/skaffold.yaml">skaffold.yaml</walkthrough-editor-open-file> for you.

yaml

apiVersion: skaffold/v2beta8
kind: Config
metadata:
  name: kpt-cl
build:
  artifacts:
  - image: "frontend"
    context: php-redis
deploy:
  kpt:
    dir: config

This file contains two stages: build and deploy.

<walkthrough-editor-select-line filePath="guestbook-cl/skaffold.yaml" startLine="4" endLine="4" startCharacterOffset="0" endCharacterOffset="5">build</walkthrough-editor-select-line> defines the methods to build and upload the application images (by default, it uses docker)
<walkthrough-editor-select-line filePath="guestbook-cl/skaffold.yaml" startLine="8" endLine="8" startCharacterOffset="0" endCharacterOffset="6">deploy</walkthrough-editor-select-line> defines the methods to manage the app configuration and deploy the application to the bundled cluster.

In the example, the configurations will build an image <walkthrough-editor-select-line filePath="guestbook-cl/skaffold.yaml" startLine="6" endLine="6" startCharacterOffset="12" endCharacterOffset="20">frontend</walkthrough-editor-select-line> and use kpt to hydrate[1] and deploy the applications to the cluster.

The <walkthrough-editor-select-line filePath="guestbook-cl/skaffold.yaml" startLine="6" endLine="6" startCharacterOffset="12" endCharacterOffset="20">frontend</walkthrough-editor-select-line> source code is stored in <walkthrough-editor-open-file filePath="guestbook-cl/php-redis/guestbook.php">guestbook-cl/php-redis</walkthrough-editor-open-file> and its configurations are stored in <walkthrough-editor-open-file filePath="guestbook-cl/config/frontend/deployment.yaml">guestbook-cl/config</walkthrough-editor-open-file>.

<walkthrough-pin-section-icon></walkthrough-pin-section-icon> Glossary

[1] Hydrate means rendering a kustomize directory or a kpt package to a flatten configuration, each of whose resources contains the full set of the object information.

Running skaffold

Time to complete: About 1 minutes

bash

skaffold dev

skaffold dev is the essential skaffold command. It builds the application and then deploys the applications to the bundled cluster.

Once the deployment is complete, you can exit with Ctrl+C.

<walkthrough-notification-menu-icon></walkthrough-notification-menu-icon> Tips

skaffold dev can automatically detect file changes and kick off a re-deploy. So you don’t need to rerun the command if the file changes.

Validating the config

Time to complete: About 10 minutes

Validating the configurations helps both the app development and devOps to be efficient in a fragile environment.

This step uses a kubeval example to show how kpt functions[2] can validate the app configuration and makes the validation itself as a declarative config.

Download the kpt function resource

bash

kpt pkg get https://github.com/GoogleContainerTools/skaffold.git/codelab/01_kpt-validate/resources/validation-kubeval validation-kubeval

Now let's update the skaffold.yaml to use the new validator. Replace the following code with the .deploy section in the <walkthrough-editor-select-line filePath="guestbook-cl/skaffold.yaml" startLine="8" endLine="10" startCharacterOffset="0" endCharacterOffset="100">skaffold.yaml</walkthrough-editor-select-line>

See the full skaffold.yaml
yaml
```
deploy:
  kpt:
    dir: config
    fn:
      fnPath: validation-kubeval
      network: true
```

<walkthrough-editor-select-line filePath="guestbook-cl/skaffold.yaml" startLine="12" endLine="12" startCharacterOffset="6" endCharacterOffset="12">.deploy.kpt.fn.fnPath</walkthrough-editor-select-line> refers to the kpt function directory we just downloaded.
<walkthrough-editor-select-line filePath="guestbook-cl/skaffold.yaml" startLine="13" endLine="13" startCharacterOffset="6" endCharacterOffset="13">.deploy.kpt.fn.network</walkthrough-editor-select-line> enables the kpt access to the network. This is required to run the function in a docker container.

<walkthrough-pin-section-icon></walkthrough-pin-section-icon> Glossary

[2] kpt function is a kubernetes resource with a config.kubernetes.io/function annotation. Read more here

Verifying the validation

"happy path"

Let's run skaffold dev. Now it will validate the resource according to the functions in <walkthrough-editor-select-line filePath="guestbook-cl/skaffold.yaml" startLine="14" endLine="14" startCharacterOffset="7" endCharacterOffset="13">fnPath, and then deploy the resource to the cluster.

bash

skaffold dev

"sad path"

Since the validation passes silently, let's break the kubeval to prove the validation works!

In <walkthrough-editor-open-file filePath="guestbook-cl/config/frontend/deployment.yaml">config/frontend/deployment.yaml</walkthrough-editor-open-file>, remove the <walkthrough-editor-select-line filePath="guestbook-cl/config/frontend/deployment.yaml" startLine="18" endLine="18" startCharacterOffset="0" endCharacterOffset="30">spec.template.spec.containers.image</walkthrough-editor-select-line> field (in line 19)

You can either manually delete the line or run the following command
bash
```
sed -i '19d' ./config/frontend/deployment.yaml
```
Check the skaffold dev output.
bash
```
skaffold dev
```
You should expect the following warning about the missing field.
terminal
```
The Deployment "frontend" is invalid: spec.template.spec.containers[0].image: Required value
```
You can add back the removed line by copying the following command and running it in the terminal.
shell
```
sed -i '18 a \        image: "frontend"'     ./config/frontend/deployment.yaml
```

<walkthrough-notification-menu-icon></walkthrough-notification-menu-icon> Tips

You can find all the kpt validation functions from this catalog

Or write your own versions. See instructions.

Conclusion

<walkthrough-conclusion-trophy></walkthrough-conclusion-trophy>

Congratulations, you known how to validate configurations in skaffold! You can explore the full kpt configuration from the skaffold.yaml reference doc.

You can also try out other kpt features like kpt pkg and kpt cfg from the user guide. They will be supported in skaffold soon. Stay tuned!

Validate Your Configurations in skaffold Workflow

Validate Your Configurations in skaffold Workflow

Introduction

What is kpt?

What kpt can help you with

What you'll learn

Prerequisites

Install skaffold

Install kpt

Install kustomize

Getting started

Taking a deeper look at the skaffold.yaml

Running skaffold

Validating the config

Verifying the validation

"happy path"

"sad path"

Conclusion

Install `skaffold`

Install `kpt`

Install `kustomize`