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This series of articles is dedicated to Flagger, a tool that integrates with Kubernetes, the popular container orchestration platform. Flagger enables automated deployments and will be one step closer to a continuous deployment process.

This article is the first of the series and also the only one where we won’t use Flagger yet… this article will walk through how you to run a Kubernetes cluster on your local environment and deploy an application which will be accessible via an Istio gateway.

Docker

Install Docker by installing the Docker Desktop for Mac application, you can refer to the official installation guide. For Windows users, the equivalent application “Docker for Windows” exists.

In the next part, we will also use Docker for Mac to set up our local Kubernetes cluster. Note that this tutorial has been tested with Docker for Mac 2.4.0.0 that includes a Kubernetes Cluster in version 1.18.8, this is the latest at the moment of writing.

If you use a different version, technology is moving fast so I cannot guarantee that the commands used in this series will work without any adjustment.

Mirror HTTP Server

First a few words about the application Mirror HTTP Server we will use in this series of articles.

MHS is a very simple JavaScript application based on Node.js using the framework Express which allows you to customize the HTTP response received by setting specific HTTP headers in the request. The Docker image is publicly available on the Docker Hub. You can consult the Github repo of the project to find out more, please note that I am not the author.

This little app is exactly what we need to test the capabilities of Flagger to simulate 200 OK responses and 500 Internal Server Error responses.

Let’s pull the Docker image:

And run a new container that uses it:

Then let’s make sure it is functioning properly:

You should receive an HTTP 200 OK response:

While:

will return an HTTP 500 response:

For simplicity, we use the curl command, but you can use your favourite tool, e.g. Postman.

Kubernetes

Now that you’ve installed Docker for Mac, having a Kubernetes cluster running locally will be a simple formality. You just need to check a box!

Enable Kubernetes with Docker for Mac

If the light is green, then your Kubernetes cluster has successfully started. Please note, this requires a significant amount of resources, so don’t panic if the fan is running at full speed and it takes a bit of time to start…

Kube dashboard

We will install our first application in our Kubernetes cluster.

Kubernetes via Docker does not come with the dashboard by default, you have to install it yourself. This dashboard is very practical and provides a graphical interface of what is going on in your cluster and will save you from having to enter kubectl commands.

The dashboard is protected, but you can use the default user to access it. You can generate a default token via this command:

Copy it.

You will need to re-use this command and /or the token copied if your session has expired, this happens when you don’t interact with the dashboard for a little while.

Finally, create a proxy to access the dashboard from the browser (this command will need to run indefinitely):

If you access http://localhost:8001/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy/#!/login and use the token that you copied to authenticate, you should see this screen.

Kube Dashboard

Helm

We use Homebrew for the installation of Helm. Homebrew is a handy package manager available for Mac.

We will use Helm to install Istio and the MHS application in our cluster. Helm is a bit like Homebrew, but for Kubernetes. We are using version 3. Helm will save you from having to enter many kubectl apply commands.

Let’s install Helm 3 with:

To verify that Helm has been installed:

You should have a similar output (note that Helm 3.3.4 is the latest version at the time of writing):

Istio & Prometheus

Now, we are going to install the Istio Service Mesh. For full explanations and the benefits of using a Service Mesh, I invite you to read the official documentation.

First of all, you must increase the memory limits of your Kubernetes via Docker, otherwise you will run into deployment issues. Your laptop’s fans will recover, don’t worry…

Here is my configuration:

Kubernetes Configuration in Docker for Mac for Istio

I followed the Docker Desktop recommendations for Istio.

Let’s go and install Istio 1.7.3 (the latest version at the time of writing). First, download the source:

Add the istioctl client to your path:

Install Istio with the provided client, we use the demo profile:

After a few minutes, you should get a message confirming that Istio has been installed. And voilà!

To install the latest version of Istio, you can simply replace the first line with curl -L https://istio.io/downloadIstio | sh -.

Add Prometheus as it’s required for Flagger:

From the Kube dashboard, verify that a new namespace has been created istio-system and that it contains the Istio tools including Prometheus.

Istio is deployed in your cluster

Why is Prometheus important? Because it is an essential component for Flagger which will provide the metrics to show if the new version of your application is healthy or not, thus it will know when to promote or rollback a version. I will come back to this in detail in the next article.

Deploying Mirror HTTP Server

Before deploying MHS, let’s create a new namespace application, we don’t want to use the default one at the root of the cluster (this is good practice). The name is too generic, but sufficient for this tutorial, in general you will use the name of the team or the name of a group of features.

Do not forget to activate Istio on this new namespace:

To deploy MHS, I created a Helm chart.

This chart was created with the helm create mhs-chart command, then I updated to use the latest image of MHS. I also added a gateway.yaml file to configure the Istio gateway so it can be accessible outside of the cluster.

Clone the chart repo:

And install MHS:

After a few moments, if you look at the dashboard, you should see 1 replica of MHS in the namespace application.

MHS is deployed in your cluster

You now have 1 MHS pod running in your Kubernetes cluster. The pod is exposed to the outside world via an Istio gateway.

To test, use the similar commands that we used against the docker container earlier:

You should receive an HTTP 200 OK response that was handled by Envoy, the proxy used by Istio:

And:

should return an HTTP 500 response:

Congratulations, you’ve come to the end of this first tutorial!

For information, you can also access MHS with your favourite browser if you run a proxy command first to expose the pod:

export POD_NAME=$(kubectl get pods --namespace application -l "app.kubernetes.io/name=mhs,app.kubernetes.io/instance=mhs" -o jsonpath="{.items[0].metadata.name}")

kubectl port-forward --namespace application $POD_NAME 8080:80

Then, navigate to http://localhost:8080/.

You should see a… blank page. This is normal, MHS does not return a body in the response and there is no HTML output!

Cleaning up resources

You can delete the MHS application and its namespace.

We don’t remove Istio / Prometheus because we will need it in the next article, but if you want to free up some resources, you can use these commands:

What’s next?

The next article will focus on the installation of Flagger and use different versions of MHS to try canary deployments. Stay tuned! In the meantime, you can stop the Kubernetes cluster by unchecking the box and restarting Docker Desktop. Your computer deserves a break.

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Last Wednesday, Expedia organized the first CoderDojo in our London office.

CoderDojo is a volunteer-led community group for young people aged 7 to 17 to come together and learn to create cool projects with technology.

It’s free to come along and all experience levels are welcome; whether you’re new to coding or have a project idea that you want to make reality!

For this first session, we had about 10 participants aged between 7 and 13 years old.

As an ice breaker, we did the “two truths and a lie” game mentioning 3 things we had done during that day. I was quite glad that most kids fell into my trap when I said that I played PlayStation at work, and they all thought it was the lie… :)

We organized different activities depending on what the kids were interested in:

• Scratch, using drag & drop blocks instead of traditional code, to make a hippo fly or build more complex projects
• Learn basic algorithm skills based on Star Wars or Flappy Bird games
• Use of the BBC Micro:Bit to create games or simulate robot emotions

CoderDojo @ Expedia London

CoderDojo @ Expedia London

At the end of the activity, the kids were invited to show what they achieved over the last hour. It was nice to see the majority of them really happy & enthusiastic to tell us about what they built.
Sharing knowledge and collaboration are very important soft skills.

In summary, it was fun for the kids but also the mentors!

CoderDojo Mentors: Veli, Alice, Adam, Ana, Fabian, Nicola

After receiving spontaneously good feedback from some participants at the end, we can say this first session was a success. We obviously have room for improvement and already got some new ideas for the next session.

We are planning to have a monthly Dojo, the 3rd Wednesday of each month, which means the next one will be on August, 21st.

Whether you are a kid, a parent or a mentor, we hope to see you soon at the second one! More info and registration at London Angel Expedia CoderDojo.