This repo contains the Microservice/Kubernetes examples I created for my "Developing Micro-services with Kubernetes" talks given in April 2018 at CodeEurope.pl in Warsaw and Wroclaw, Poland.
Refer to https://mjbright.github.io/Talks/index.html#201804_codeeu for the slides and other information about those talks.
A revised version will be available after Pyconfr, Lille happening in October 2018.
The demo at Wroclaw was run on a Mac AirBook Pro using
- minikube as a single-node Kubernetes cluster
- a simple demo dashboard integrating a test button & output, a shell console and a cluster visualization
The demo has also been tested/documented on
- Windows10 using Docker Desktop to provide the Kubernetes cluster, using a MSYS2 buid of ttyd.
- Ubuntu 18.04.1 LTS
The demo dashboard integrates several components
- the button and output for a simple Flask/Redis counter application
- a web console based on ttyd: allowing running of shell commands in the demo browser window
- a Kubernetes visualization
You don't need to rebuild this application, you can use the 'mjbright/flask-web' images available on DockerHub.
The steps to deploy these images are described later in this document.
Nevertheless the sources for this application are located in the subdirectory kubernetes-flask-redis-microservice along with a script to automatically build the different versions of the app (v1, v2, v3) used in the demo.
The visualizer is derived from a fork of Brendan Burns' K8S visualizer, implemented using jsPlumb library.
A modified version is integrated into the demo, it's sources are in the subdirectory live-k8s-visualizer, along with a script to start the visualizer.
The steps to deploy the visualizer are described later in this document.
Setup instructions are provided in SETUP.md - this document describes how to setup the full dashboard. You can also run the demo steps with minikube or any other Kubernetes cluster.
Below I detail most of the steps of the CodeEurope demo with the exception of the use of Nginx on minikube. This will come later.
Refer to https://mjbright.github.io/Talks/index.html#201804_codeeu for the slides and other information about those talks.
You can refer to the presentation slides to see the commands used.
The demo steps are described from slide#23 onwards.
The steps are described in greater detail in those slides, and where these "declarative" steps (i.e. by "apply"ing the yaml files which are a declaration of the desired configuration) are also compared to alternative "imperative" such as kubectl run or kubectl expose.
Deploy a Redis backend (this will create a Deployment, a ReplicaSet and one instance of a Redis pod).
kubectl apply -f redis-deployment.yaml
Deploy a Flask app as frontend (this will create a Deployment, a ReplicaSet and one instance of a Flask-based application server pod).
kubectl apply -f flask-deployment.yaml
Expose the Redis service on a "known port" so that the flask-app can access it.
kubectl apply -f redis-service.yaml
Expose the Flask service so that we can connect to it.
kubectl apply -f flask-service.yaml
NOTE: We have not yet set the exposed service port in our demo page - the button still displays PORT_UNSET.
We rerun the create_demo_html.sh script now with the '-s' option to recuperate the service port:
cd live-k8s-visualizer/
./create_demo_html.sh -s
Now reload the demo page and we see that the port number now appears in the button and the first request to our service has been made "Redis counter value=1".
Press the button to see the value increment.
In the file flask-deployment.yaml, modify the line
replicas: 1
to
replicas: 4
Now reapply this resource file:
kubectl apply -f flask-deployment.yaml
In the file flask-deployment.yaml, modify the line
- image: mjbright/flask-web:v1
to
- image: mjbright/flask-web:v2
Now reapply this resource file:
kubectl apply -f flask-deployment.yaml
In the file flask-deployment.yaml, modify the line
- image: mjbright/flask-web:v2
to
- image: mjbright/flask-web:v3
Now reapply this resource file:
kubectl apply -f flask-deployment.yaml
