skaffold

skaffold

Skaffold is a tool that makes the onboarding of existing applications to Kubernetes simple and repeatable. It currently handles the build and deploy lifecycle actions for Kubernetes. Skaffold has a simple, pluggable architecture that allows you to use some of the best community tooling available, such as docker or helm.

Some of the main features

• No server-side component. No additional overhead to your cluster.
• Supports existing tooling and workflows. Build and deploy APIs make each implementation composable to support all types of workflows.
• Multi-image and multi-manifest support.
• Switch from development mode to run mode with no configuration changes

Skaffold has two main modes: skaffold run and skaffold dev

skaffold dev

This is the development mode for skaffold.

• A filesystem watcher to watch the dependencies of your docker images
• Streaming logs from deployed containers
• Continuous build-deploy loop, warn on errors

Use for:

• Local development

skaffold run

Run runs a skaffold pipeline one, exiting on any errors in the pipeline.

Use for:

• Continuous Integration or Continuous Deployment tools

Getting Started

Prerequisites

What you'll need installed

• skaffold

  • We don't have official releases yet, but we do publish CI builds on every merged PR. To download the latest Linux build, run:

    curl -Lo skaffold https://storage.googleapis.com/skaffold/builds/latest/skaffold-linux-amd64 && chmod +x skaffold && sudo mv skaffold /usr/local/bin
    

    To download the latest OSX build, run:

    curl -Lo skaffold https://storage.googleapis.com/skaffold/builds/latest/skaffold-darwin-amd64 && chmod +x skaffold && sudo mv skaffold /usr/local/bin
    

• Kubernetes Cluster

• kubectl

  • configured with the current-context of your target cluster
  • In the future, we'll support more deployment strategies and drop this dependency

• docker

  • In the future, we'll support more build strategies and drop this dependency

• Docker Image Repository

  • Your docker client should be configured to push to an external docker image repository. If you're using a minikube cluster, you can skip this requirement.

If you're using minikube you'll only need

• skaffold
• minikube
• kubectl

Development

To get started, change the imageName and IMAGE_NAME parameters of examples/getting-started/skaffold.yaml. This should be a fully qualified image name that your docker client is configured to push to.

From the root directory of this repository,

$ skaffold dev -f examples/getting-started/skaffold.yaml

You should see the output (for verbose output, append -v debug)

INFO[0000] Skaffold v0.1.0
INFO[0000] Starting build...
Sending build context to Docker daemon   7.68kB
Step 1/5 : FROM golang:1.9.2
 ---> 138bd936fa29
Step 2/5 : WORKDIR /go/src/github.com/GoogleCloudPlatform/skaffold/examples/getting-started
 ---> Using cache
 ---> bd3002e4d850
Step 3/5 : COPY main.go .
 ---> Using cache
 ---> 7dcfea090d8f
Step 4/5 : RUN go build -o app main.go
 ---> Using cache
 ---> a69a1073e6da
Step 5/5 : CMD ./app
 ---> Using cache
 ---> 5c6041e4ee28
Successfully built 5c6041e4ee28
Successfully tagged b93e205a1a6d9da76ccb0b4a65f2df16:latest
Successfully tagged changeme:5c6041e4ee28b49ffca084eb25fa95e580b83992754d65ec60f0e90df6ee2f98
INFO[0000] Starting deploy...
INFO[0000] Deploying examples/getting-started/k8s-deployment.yaml
INFO[0000] Found dependencies for dockerfile [examples/getting-started/main.go]
INFO[0000] Added watch for examples/getting-started/Dockerfile
INFO[0000] Added watch for examples/getting-started/main.go

At this point, you should be able to see some output from the pod with kubectl

$ kubectl logs getting-started
Hello world!
Hello world!
...

Now, lets update examples/getting-started/main.go

diff --git a/examples/getting-started/main.go b/examples/getting-started/main.go
index 64b7bdfc..f95e053d 100644
--- a/examples/getting-started/main.go
+++ b/examples/getting-started/main.go
@@ -7,7 +7,7 @@ import (

 func main() {
        for {
-               fmt.Println("Hello world!")
+               fmt.Println("Hello jerry!")
                time.Sleep(time.Second * 1)
        }
 }

Now you should see the application has updated

$ kubectl logs getting-started
Hello jerry!
Hello jerry!
...

Run pipeline once

There may be some cases where you don't want to run build and deploy continuously. To run once, use

$ skaffold run -f examples/getting-started/skaffold.yaml

Docker commands

Skaffold exposes some the of the dockerfile introspection functionality that it uses under the hood.

skaffold docker deps

Many build systems require the developer to manually list the dependencies of a dockerfile. Skaffold can inspect a dockerfile and output the file dependencies.

$ skaffold docker deps --context examples/getting-started -v error
examples/getting-started/main.go

Example Makefile rule for conditional docker image rebuilds

out/getting-started: $(shell skaffold docker deps -c examples/getting-started -v error)
	docker build -t getting-started . -q > out/getting-started

skaffold docker context

Skaffold can also generate a tarball that can be used as a "docker context" for hosted build systems. To use this with Google Cloud Build:

$ skaffold docker context --filename examples/getting-started/Dockerfile --output=context.tar.gz
$ gcloud container builds submit context.tar.gz --tag="gcr.io/$(gcloud config get-value project)/skaffold-context:latest"

This tarball will contain only the sources needed to build the Docker image, which will result in a faster upload than the default behavior.