Skaffold and Rancher Desktop

Skaffold is a command line tool that facilitates continuous development for Kubernetes-native applications. Skaffold handles the workflow for building, pushing, and deploying your application, and it provides building blocks for creating CI/CD pipelines. This enables you to focus on iterating on your application locally while Skaffold continuously deploys to your local or remote Kubernetes cluster. To learn more about Skaffold, refer to the project docs here.

In order to demonstrate the steps to set up Skaffold with Rancher Desktop, a sample nodejs app example is provided within the Rancher Desktop docs repository here.

Important: Skaffold only works with dockerd (Moby). Therefore, make sure to select your runtime as dockerd from the Kubernetes Settings panel in the Rancher Desktop UI.

  1. Visit https://skaffold.dev/docs/install/ to install Skaffold.

  2. Clone the Rancher Desktop docs repository and navigate to the express-sample in a terminal as follows:

    1. cd docs.rancherdesktop.io/assets/express-sample

  3. Run skaffold init.

    Per the Skaffold docs,skaffold init walks through your project directory and looks for any build configuration files such as Dockerfile, build.gradle/pom.xml, package.json, requirements.txt, or go.mod.

    We will select Dockerfile and package.json in our example. This will generate the initial configuration file that you can modify as needed. When prompted, select yes to write your config to skaffold.yaml.

  4. In your editor, review your app.js and manifests.yaml files. Note that in manifests.yaml, you will have a deployment config as well as a service config. It is only necessary to have 1 replica for testing purposes.

  5. Back in your terminal, you’ll notice that you will have two options: skaffold run that lets you build and deploy, and skaffold dev that allows you to enter development mode with auto-redeploy. We will use skaffold dev in this example.

    You will need to have push access to the image repository. You can either use your docker login, set up a local registry, or build locally without pushing to an image registry:

  • Docker Hub
  • Local Registry
  • Local Build

Before running skaffold dev, use your docker login if you have a Docker Hub account. Then, in the files skaffold.yaml and manifests.yaml replace matamagu/express-sample for YOUR_DOCKER_HUB_USERNAME/express-sample as skaffold dev will push the built image to DockerHub.

You can set up a local registry by first running this command: 

  1. docker run -d -p 5000:5000 --restart=always --name registry registry:2

Then:

  1. skaffold dev --default-repo=localhost:5000

You can build locally without pushing to the image registry by setting your workloads imagePullPolicy to IfNotPresent in your manifests.yaml file. You will also need to update your skaffold.yaml with the following variables in order to implement this change as noted below:

Details

Example YAML

  1. apiVersion: skaffold/v2beta29
  2. kind: Config
  3. metadata:
  4.   name: skaffold
  5. build:
  6.   local:
  7.     push: false
  8.     useDockerCLI: true

As you go through your development, Skaffold will detect any changes and will automatically go through the build and deployment process again. You will be able to see any changes reflected in the cluster.

  1. Point your web browser to localhost:3000, and you will see the express-sample screen.