team recently an exciting new feature that allows to sync files between your machine and the development container, making a big step forward in supporting interpreted languages like Node.js. Skaffold announced is a command line tool to develop applications against a Kubernetes cluster (either a local Minikube or a remote cluster). Skaffold handles the build, push and deploy process of the image upon code change. Until today, Skaffold was (IMHO) not well-suited to interpreted languages like , due the inherent slowness of the process. With version 0.16.0, Skaffold an hybrid approach, allowing to take advantage of the usual auto-reload mechanisms used by Node.js developers (e.g.: ): Skaffold Node.js supports nodemon When a js file changes, Skaffold syncs it with the container and the app is restarted by nodemon When a file change requires to rebuild the container (for example, a change to ), Skaffold does the full rebuild, push and deploy package.json This hybrid approach is perfectly suited to a large class of technology stacks, like Node.js, React, Angular, Python, etc. Quick tutorial Code available in the . Skaffold [master](https://github.com/GoogleContainerTools/skaffold/tree/master/integration/examples/nodejs) branch Install Skaffold requires a Kubernetes cluster. A good local choice is Minikube or a recent (edge) for Mac or Docker for Windows. Installing Skaffold Docker Create a Node.JS app Init : npm npm init Add the Express web framework to : package.json npm install express nodemon --save Remove locally: node_modules rm -rf node_modules Add the run command to the section in : nodemon scripts package.json "scripts": {"dev": "nodemon index.js"}, Create : index.js Dockerize it Create a : Dockerfile Create a Kubernetes pod definition : k8s-pod.yaml If you use an editor that writes temporary files (like ) you need a file to make sure that temporary files do not trigger a container build: vim .dockerignore Skaffold configuration Create a : skaffold.yaml The section points to the pod definition, while the section points to current directory, where the is located. The clause disables the full rebuild/push/deploy for file changes and enables the sync process of those files to the container. deploy build Dockerfile sync *.js Running Skaffold skaffold dev This command starts the Skaffold file watcher, builds the image and deploys it on the cluster; it also shows you the application logs and it handles port forwarding for you. When you see: ...[node] Example app listening on port 3000! You’re ready to access the application: $ curl localhost:3000Hello World! Development workflow Make some changes to . You will see that the modified file is synced to the container and restarts the application: index.js nodemon Syncing 1 files for gcr.io/k8s-skaffold/node-example:dirty-11d1880Watching for changes every 1s...[node] [nodemon] starting `node index.js`[node] Example app listening on port 3000! $ curl localhost:3000Hello World - changed! Fast and easy! If you change a file that requires rebuilding the container (like adding a dependency in ) the full build/push/deploy mechanism is triggered: package.json Starting build...Found [minikube] context, using local docker daemon.Building [gcr.io/k8s-skaffold/node-example]...Sending build context to Docker daemon 10.34MBStep 1/5 : FROM node:8.12.0-alpine---> df48b68da02a ... Build complete in 8.236026621s ... [node] Example app listening on port 3000! The time it takes depends on the complexity of your . package.json Future Improvements Even if changing does not happen that often, rebuilding a complex app can be lengthy. A mechanism is needed to make use of cache to speed up the process. package.json npm My talk If you want to lean more about local development with Kubernetes, you can watch my at the All Day DevOps conference 2018. talk
