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Tako workflow example with a simple Node.js App

Development workflow example with a simple Node.js app

Get Tako

  • Download Tako & add to the PATH

Initialise project

Inside the project directory (./examples/node-app) instruct Tako to:

  • provide a way to adjust Kubernetes specific configuration for 3 distinct environments,
  • prepare the app for use with Skaffold.
$ tako init -e staging -e prod --skaffold

You will notice that 3 separate environment specific configuration files have been created:

Added environment specific override files:

|- docker-compose.env.dev.yaml
|- docker-compose.env.staging.yaml
|- docker-compose.env.prod.yaml

(The dev configuration is created by default by Tako).

Adjust Kubernetes specific application parameters for each of the components as and when necessary. This is done via Compose extensions.

It'll also bootstrap the Skaffold config file (skaffold.yaml). If skaffold.yaml previously existed then it'll add additional profiles to it.

Iterate on the application

One-off K8s manifests render

Once changes to base & environment specific Compose file(s) have been made

# One-off Kubernetes manifests render:
$ tako render

This will produce K8s manifests for all environments. See help for usage examples.

Inspect produced Kubernetes manifests at default k8s directory.

Watch for Compose changes and auto-rebuild K8s manifests

Run the command below to continuously watch for changes made to any of the source / environment Compose files related to your application and automatically rebuild Kubernetes manifests for changed environments.

See help for usage examples.

# Watch Compose changes and auto render Kubernetes manifests:
$ tako dev

Watch for Compose and Application source code changes with Build/Push/Deploy loop enabled

Watch for changes to your application's Compose files plus project source code. Then, automatically rebuild the K8s manifests and build/push/deploy the app via Skaffold dev loop to any Kubernetes cluster upon detected changes.

See help for usage examples.

# Watch Compose and App source code changes, render manifests and
# build/push/deploy with Skaffold:
$ tako dev --skaffold

Open the browser at http://localhost:8080. You should see Hello World displayed on the screen.

NOTE: The command above will use current kubectl context, and will attempt to deploy your app to default namespace. Those can be adjusted with --kubecontext=<context> & --namespace=<ns> options added to the command above.

IMPORTANT: If --kubecontext is pointing at remote Kubernetes cluster you need to make sure you adjust the image in docker-compose.yaml file so that it points at registry you control and are able to push to. Should that be a private registry then make sure that the remote Kubernetes cluster is able to pull images from it.

Once the app has been built, pushed and deployed via Tako's Skaffold integration you may inspect that the Node app is running in your cluster:

# List Kubernetes application pods for the Node.js app:
$ kubectl --context docker-desktop -n default get po

NAME                   READY   STATUS    RESTARTS   AGE
app-69d87ffbc8-pq4bs   1/1     Running   0          9s

Now, try to adjust number of replicas for the app by modifying x-k8s.workload.replicas value to 2. You should observe dev loop pick up all the changes and do the hard work of generating K8s manifests, building, pushing and deploying your application automatically.

# List Kubernetes application pods for the Node.js app after change
# to desired replicas number:
$ kubectl --context docker-desktop -n default get po

NAME                   READY   STATUS        RESTARTS   AGE
app-85b85cf987-8ngks   1/1     Running       0          14s
app-85b85cf987-h9l2m   1/1     Running       0          16s

Now try and modify the app source code by changing res.send('Hello World!'); in server.js file to something different e.g. res.send('FOO BAR!');. Once changes are saved the application will be automatically rebuilt and redeployed. Visit http://localhost:8080 and see FOO BAR appearing on the screen.

That's it. Issue Ctrl+C to stop the dev loop and delete objects deployed to Kubernetes namespace.