Flask project with CircleCI and gcloud

This is a sample project to show how you can use Google Cloud and CircleCI to host apps on a Kubernetes cluster.

The project requires some inital setup that

Creates a Kubernetes Engine
Initiall creates the app deployment and service so it's reachable from an IP

Initial deployment

Kubernetes Cluster Engine

First, to have a cluster to run apps on, we need to create a Kubernetes Engine with a Google Cloud account. Assuming you have gcloud set up:

$ gcloud deployment-manager deployments create kube-cluster-deployment --config deployment-manager/kube-cluster-deployment.yaml

Then get the credentials for kubectl to run commands on the cluster:

gcloud container clusters get-credentials kube-cluster

Upload initial image

As preparation for the kubernetes deployment, we need to have an image that is available:

$ docker build -t flask-test .
$ docker tag flask-test gcr.io/symbolic-axe-123456/flask-test:latest

Create deployment and service

We can now create the initial deployment and service using a yaml file with the specifications. The yaml file refers to the image we just uploaded.

$ kubectl create -f kube-deployments/flask-deployment.yaml

Wait for an external IP to appear

$ kubectl get svc
NAME            TYPE           CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
flask-service   LoadBalancer   10.27.245.152   <pending>     80:30633/TCP   47s
kubernetes      ClusterIP      10.27.240.1     <none>        443/TCP        1m
(env) [niels@leoilap flask-test] (master)$ kubectl get svc
NAME            TYPE           CLUSTER-IP      EXTERNAL-IP      PORT(S)        AGE
flask-service   LoadBalancer   10.27.245.152   35.195.123.199   80:30633/TCP   1m
kubernetes      ClusterIP      10.27.240.1     <none>           443/TCP        1m

All done!

Now, assuming you've set up the required environment variables on CircleCi, you should be able to commit and push to this repository, and your app will be updated accordingly.

Required environment variables for CircleCI

Circle will require the following variables: