isabella232 / tekton-demo

Demonstration of Tekton pipelines to supplement our blog post

Tekton Demo

Disclaimer

The code in this repository is a demonstration. Please do not use in production. This demonstration will create billable GCP resources.

Introduction

This demonstration ties together with the Jetstack blogpost on Tekton. Please read this blogpost to familiarise yourself with Tekton's underlying concepts.

At the end of the demonstration, you will have a simple website being served from Kubernetes. Using Tekton, the container image used to serve the website will have been built from within the same Kubernetes cluster that serves the website. As Tekton TaskRuns execute in a Kubernetes Pod, it's possible to influence how these workloads are scheduled. In this demo, the website is served from n1-standard-1 nodes, while the CI/CD is carried out on pre-emptible f1-micro nodes.

What to expect from this demo

For this we'll use Paul Bouwer's hello-kubernetes repo on GitHub, which serves a simple website that shows which Pod is currently serving the website. Fork this repo, and specify the fork in the Makefile (variable GIT_REPO_URL).

The build may initially fail with an error regarding "unexpected end of statement while looking for matching single-quote". This can be rectified by removing the single-quote character from the org.opencontainers.image.description field of the hello-kubernetes repo's Dockerfile.

After modifying the forked repo, we need to build an image and push it to a container registry, which will be achieved by Kaniko from within the cluster.

To change the background colour you can modify static/css/main.css and commit this code to your fork of hello-kubernetes. We can now bump the version number in the Makefile (lines 22-24) and run make tekton_trigger, which will run a Tekton pipeline, and apply the new image version to the Kubernetes cluster.

Using this repository

Run make for an overview of the repo's functionality.

Please run make check_requirements to check which dependencies are missing from your local environment for this demo to work.

Setup

Google Cloud Platform

This assumes that you have already run gcloud init in your local environment.

Firstly, ensure that the relevant API services have been enabled in your account:-

gcloud services enable storage-api.googleapis.com
gcloud services enable cloudresourcemanager.googleapis.com
gcloud services enable compute.googleapis.com
gcloud services enable container.googleapis.com
gcloud services enable iam.googleapis.com

We'll need to be able to authenticate to push to a Google Container Registry (GCR). For this authentication, Kaniko requires a storage admin role. You can use the Makefile to generate a GCP Service Account and download an authorisation key:-

make kaniko_sa_create kaniko_sa_secret_create

This will output a JSON file to the repository's secrets/ directory, where the Makefile expects to find the credentials.

Usage

Infrastructure

Run make demo_infra to create a GKE cluster with two node pools: web-backend to serve the website, and a pre-emptible cicd node pool to run Tekton pipelines.

Tekton resources

Run make demo_resources to install Tekton on the cluster (in the tekton-pipelines namespace), along with a demo website (in the website-dev namespace).

Run make tekton_trigger to run a build.

make tekton_pretty will output some relevant information from the build steps. As a Tekton Run is just another Kubernetes object, its outputs that can be logged and read like any other resource using kubectl get <POD_NAME> -o yaml. We can also follow the logs of the containers running within the Pod using kubectl -n cicd logs -f <POD_NAME> <CONTAINER>.

Website

Within a few minutes, GKE will provision an IP address for your LoadBalancer Service endpoint, which you can discover by running:

kubectl --namespace website-dev get svc

Once the image has been built (using make tekton_trigger) and deployed (using make website_deploy), the website will be served at this external IP address.

Cleanup

Don't forget to delete the cluster using make demo_delete once you're finished, which will delete the Kaniko ServiceAccount and the demonstration's GKE cluster. Also delete any container images that have been pushed to your Container Registry.

Further experimentation

Modify lines 18-24 of the Makefile to try building containers based on other Git repos that have Dockerfiles in their root.