Deploying OpenWhisk on Kubernetes in Docker for Mac

Overview

If you are using a Mac as your development machine, the simplest way to get a Kubernetes cluster for local development is to use the built-in support for running a single node Kubernetes cluster that is available in Docker 18.06 and later. This will let you use Helm to deploy Apache OpenWhisk to Kubernetes on your laptop without needing any additional virtualization software installed.

Initial setup

Creating the Kubernetes Cluster

Step-by-step instructions on enabling Kubernetes in Docker are available as part of the Getting started documentation from Docker.

In a nutshell, open the Docker preferences window, switch to the Advanced panel and make sure you have at least 4GB of Memory allocated to Docker. Then switch to the Kubernetes panel, and check the box to enable Kubernetes. It is recommended that you use the kubectl cli that is installed by Docker in /usr/local/bin, so please make sure it is appears in your path before any kubectl you might also have installed on your machine. Finally, pick the docker-for-desktop config for kubectl by executing the command kubectl config use-context docker-for-desktop.

Configuring OpenWhisk

You will be using a NodePort ingress to access OpenWhisk. Assuming kubectl describe nodes | grep InternalIP returns 192.168.65.3 and port 31001 is available to be used on your host machine, a mycluster.yaml for a standard deployment of OpenWhisk would be:

whisk:
  ingress:
    type: NodePort
    apiHostName: 192.168.65.3
    apiHostPort: 31001

nginx:
  httpsNodePort: 31001

Hints and Tips

One nice feature of using Kubernetes in Docker, is that the containers being run in Kubernetes are also directly visible/accessible via the usual Docker commands. Furthermore, it is straightforward to deploy local images by adding a stanza to your mycluster.yaml. For example, to use a locally built controller image, just add the stanza below to your mycluster.yaml to override the default behavior of pulling a stable openwhisk/controller image from Docker Hub.

controller:
  imageName: "whisk/controller"
  imageTag: "latest"

Limitations

Using Kubernetes in Docker for Mac is only appropriate for development and testing purposes. It is not recommended for production deployments of OpenWhisk.

TLS termination will be handled by OpenWhisk's nginx service and will use self-signed certificates. You will need to invoke wsk with the -i command line argument to bypass certificate checking.

The docker network is not exposed to the host on MacOS. However, the exposed ports for NodePort services are forwarded from localhost. Therefore you must use different host names to connect to OpenWhisk from outside the cluster (with the wsk cli) and from inside the cluster (in mycluster.yaml). Continuing the example from above, when setting the --apihost for the wsk cli, you would use localhost:31001. This networking difference also shows up when listing apis via wsk -i api list. The listed URLs will show the cluster-internal apihost, e.g. https://192.168.65.3:31001/api/<UID>/<PATH>, to invoke the api from outside the cluster you should use localhost:31001 instead, e.g. https://localhost:31001/api/<UID>/<PATH>.