Flask and Express App Example Documentation

Here you will find the accompanying documentation for the infrastructure part of the Flask and Express app example.

Everything you need to get the example up and running for yourself.

Prerequisites

You will need to install a few things first. I will assume you're running a macOS and you're using brew as a package manager.

Minimal Prerequisites

• Docker Desktop
• minikube
• kubectl

Optional Prerequisites

• k9s

Here's only one example for installing minikube using brew.

brew install minikube

It's as simple as that.

Setting up your computer

There is a little step you have to do prior to deploying your cluster and workloads. We will use an internal custom domain to access our services, which will be called containers.test

For this we need to change our hosts file and add the necessary entries. First you need to find your cluster's IP address. So we need to get a cluster spun up.

Creating a minikube cluster

To initialize and spin up a minikube cluster, all you need to do is issue one single command.

minikube start

That's literally all you need to do. Now you wait for it to be up. We'll check it is ready by issuing the minikube status command.

minikube status

It should tell you something similar to this.

➜  ~ minikube status
minikube
type: Control Plane
host: Running
kubelet: Running
apiserver: Running
kubeconfig: Configured

Now we need the IP address of our cluster, which we'll get using minikube ip.

minikube ip

Copy that IP address to your clipboard and open your /etc/hosts file with your favorite text editor with root privileges to add the necessary entries.

This his how my hosts file looks like.

##
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting.  Do not change this entry.
##
127.0.0.1	localhost
255.255.255.255	broadcasthost
::1             localhost
# Added by Docker Desktop
# To allow the same kube context to work on the host and the container:
127.0.0.1 kubernetes.docker.internal
# End of section
# Manual configuration
127.0.0.1 containers.test
192.168.49.2 containers.test, flask.containers.test, express.containers.test

Note the section below # Manual configuration. This is the part we've added. First a we let the loopback address point to containers.test and then we let the IP address of the minikube cluster point to containers.local and all relevant subdomains, in this case flask.containers.test and express.containers.test.

Save and close that file.

Now we need to tell minikube to enable some addons we will use. We need the following:

• ingress
• ingress-dns

To enable those addons you use the - you've guessed it - minikube addons command.

minikube addons enable ingress
minikube addons enable ingress-dns

Now we'll simply apply our ingress.yml manifest in our local minikube cluster.

From within this respoitory you will run:

kubectl apply -f ingress.yml

We've done setting up of machine. You will need to continue from the Flask and Express applications' repositories for proceed building the Docker images, publishing them to your docker registry and deploying them into your local cluster.