Scalable microservices - Part 3

Infrastructure today is more about choosing tools than building them yourself. IT has moved up to higher-level services.

Kubernetes is an abstraction over containers. It lets you treat an entire cluster as if it were a single machine.

Pods have an IP address and can access volumes; they are the containers your apps run in.

Using nginx to reverse proxy the app in HTTPS:

Monitoring and health checks: https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-probes/
Configuration: http://kubernetes.io/docs/user-guide/configmap/
Secrets: http://kubernetes.io/docs/user-guide/secrets/

Configuration and secrets files are accessed through mounted volumes defined in the Kubernetes YAML configuration file, once the secrets and configmap have been loaded on the master node.

A service is another level of abstraction: a set of identical pods.

Services: http://kubernetes.io/docs/user-guide/services/

Sample configuration files: https://github.com/udacity/ud615/tree/master/kubernetes

Useful commands

Create a Kubernetes cluster.

gcloud container clusters create k0
gcloud components install kubectl

Create a pod.

kubectl create -f [yaml-file]

Forward a port between the cluster and the master machine.

kubectl port-forward monolith 10080:80
# http://localhost:10080
kubectl logs -f monolith

Execute a command from within the container.

kubectl exec monolith --stdin --tty -c monolith /bin/sh

Setting nginx configuration and TLS keys.

kubectl create secret generic [name] --from-file=[folderls]
kubectl describe secrets [name]
kubectl create configmap [name] --from-file [conf-file]
kubectl describe configmap [name]

Create a service

kubectl create -f [yaml-file of type NodePort]

References

Kubernetes cheatsheet