stablekernel / kubernetes

k8s bootstrapping

k8s bootstrapping

Directories in this repository contain Kubernetes configuration files for provisioning a cluster and deploying Aqueduct applications.

Prerequisites

The following assumes that you have a Google Cloud account with billing enabled and that tools such as docker, gcloud and kubectl have been installed and configured. If not, see the following references:

• Install Docker
• Install gcloud
• Install kubectl by running gcloud components install kubectl.

Cluster Provisioning

Tasks in this section need only be applied when a cluster is first created, not for each application deployed.

The objects in kube-lego and nginx-ingress-controller provide a cluster with low cost alternatives to load-balancing with SSL termination. They live in the kube-system namespace.

SSL Certificates via Let's Encrypt

Modify kube-lego/config-map.yaml by replacing <ADMIN_EMAIL> with an administrator e-mail address. Then, apply the objects in the kube-lego directory to your cluster:

kubectl apply -f kube-lego/

kube-lego will monitor your cluster to request trusted SSL certificates for deployed applications.

Nginx Ingress Controller

The nginx ingress controller is only necessary if you prefer not to use Google Cloud Load Balancer (GCLB costs $200+/yr).

Run the script nginx_deploy.sh:

sh nginx_deploy.sh

It will take a moment for nginx-ingress-lb to acquire an IP address. During that time, running the command kubectl get services -n kube-system will show something like the following:

NAME                   CLUSTER-IP      EXTERNAL-IP   PORT(S)                      AGE
default-http-backend   10.55.241.222   <nodes>       80:32516/TCP                 11d
heapster               10.55.255.209   <none>        80/TCP                       11d
kube-dns               10.55.240.10    <none>        53/UDP,53/TCP                11d
kubernetes-dashboard   10.55.240.49    <none>        80/TCP                       11d
nginx-ingress-lb       10.55.249.185   <pending>     80:32005/TCP,443:31623/TCP   6s

Where nginx-ingress-lb's EXTERNAL-IP is <pending>. Once that <pending> flips to an IP address, note the IP address and navigate to VPC Network->External IP adresses in the Google Cloud console. Locate the IP address in that list and change it's type from Ephemeral to Static. (You'll be prompted for a name which can be whatever you like.)

Important: if you delete the nginx-ingress-lb service after reserving a static IP for it, simply re-creating the service won't work. You'll need to release the reserved address before the service will start again and then reserve the IP address again.

Application Deployment

The aqueduct directory contains templates for Kubernetes objects that deploy an Aqueduct application and its PostgreSQL database. For each Aqueduct application deployed into the cluster, follow the following steps.

Note: Kubernetes object names may not contain underscores. If your application name contains underscores, substitute a dash (-) when replacing the <APP_NAME> template variable. For example, if your application name is my_app, use my-app.

0. Copy the contents of aqueduct/kubernetes into a directory named k8s in your project directory.

1. Create a new namespace with the name of your application.

kubectl create namespace <app-name>

2. Modify config/configmap.yaml and config/secrets.yaml by replacing all occurrences of <APP_NAME> with the name of your application (remembering to use dashes and not underscores), and replacing <PASSWORD> with a database password. Apply these files:

kubectl apply -f k8s/config/

Change your Aqueduct application's config.yaml to use the values from the configmap, secrets and db-service:

database:
  username: $POSTGRES_USER
  password: $POSTGRES_PASSWORD
  host: db-service
  port: 5432
  databaseName: $POSTGRES_DB

3. Add the Dockerfile in this repository to your Aqueduct project directory. Make sure that migration files are up to date by running aqueduct db validate (and running aqueduct db generate if they are not). Migration files must be a part of the docker image.

Run docker build in the project directory. The name of the image must have the format gcr.io/<PROJECT_ID>/<APP_NAME> where PROJECT_ID is the name of the Google Cloud project that the target cluster is in and APP_NAME is your application's name.

docker build -t gcr.io/<project-id>/<app-name>:latest .

Once built, push it to your project's private registry:

gcloud docker -- push gcr.io/<project-id>/<app-name>:latest

4. In both api-deployment-and-service.yaml and db-deployment-and-service.yaml, replace template variables with their appropriate values. Ensure that <IMAGE> is replaced with the full name of the image built with docker. Apply these files.

# Note: this will (intentionally) only apply top-level files in k8s and will not recursively apply files in subdirectories.
kubectl apply -f k8s/

5. Update the database schema to current version by replacing the template variables in tasks/migration-upgrade-bare-pod.yaml and then applying it:

kubectl apply -f k8s/tasks/migration-upgrade-bare-pod.yaml

Ensure this task completed by running kubectl get pod -n <app-name> db-upgrade-job. Once it has completed, delete it:

kubectl delete pod -n <app-name> db-upgrade-job

If using ManagedAuth, replace the template variables in tasks/add-auth-client-bare-pod.yaml. Apply this file, check it for completion, and delete it. Repeat for each client ID.

6. Expose your application to the world by replacing the template variables in ingress/nginx-https.yaml and applying it.

Files to check in to version control

Obfuscate any secret values - those in config/secrets.yaml and tasks/add-auth-client-bare-pod.yaml and check in all files in k8s.

Updating the Application

For application updates that do not require database schema changes, build the Docker image and push it to the registry with gcloud. If you are tagging images correctly, just set the image of your deployment:

kubectl set image deployment/api-deployment <app-name>=gcr.io/<project-id>/<app-name>:<tag> -n <app-name>

If you are reusing the latest tag, delete all pods in the api-deployment.

kubectl delete pod api-deployment-xxxxxxx-xxxxx -n <app-name>

The pods will automatically be recreated and will pull the most recent image.

If a database update is required, make sure to run aqueduct db generate before building and pushing the Docker image. Then follow the instructions in step 5 before deleting pods.

*Note: This scheme is useful for development. When deploying to production, a unique tag should be used for each image and that image name should be added to the api-deployment-and-service.yaml. Instead of deleting pods, re-apply this configuration file:

kubectl apply -f k8s/api-deployment-and-service.yaml