[Kubernates] Kubernetes Intro on Google cloud

Provision a Kubernetes Cluster with GKE using gcloud

To complete the work in this course you going to need some tools. Kubernetes can be configured with many options and add-ons, but can be time consuming to bootstrap from the ground up. In this section you will bootstrap Kubernetes using Google Container Engine (GKE).

GKE is a hosted Kubernetes by Google. GKE clusters can be customized and supports different machine types, number of nodes, and network settings.

gcloud container clusters create k0 

 

Launch a single instance:

kubectl run nginx --image=nginx:1.10.0

Get pods

kubectl get pods

Expose nginx

kubectl expose deployment nginx --port 80 --type LoadBalancer

List services

kubectl get services

To help out, here’s a Kubernetes command cheat sheet. http://kubernetes.io/docs/user-guide/kubectl-cheatsheet/

 

Create Pods

Explore config file

cat pods/monolith.yaml

apiVersion: v1
kind: Pod
metadata:
  name: monolith
  labels:
    app: monolith
spec:
  containers:
    - name: monolith
      image: udacity/example-monolith:1.0.0
      args:
        - "-http=0.0.0.0:80"
        - "-health=0.0.0.0:81"
        - "-secret=secret"
      ports:
        - name: http
          containerPort: 80
        - name: health
          containerPort: 81
      resources:
        limits:
          cpu: 0.2
          memory: "10Mi"

Create the monolith pod

kubectl create -f pods/monolith.yaml

Examine pods

kubectl get pods

It may take a few seconds before the monolith pod is up and running as the monolith container image needs to be pulled from the Docker Hub before we can run it.

Use the kubectl describe command to get more information about the monolith pod.

kubectl describe pods monolith

Interacting with Pods

Cloud shell 1: set up port-forwarding

kubectl port-forward monolith 10080:80

Open new Cloud Shell session 2

curl http://127.0.0.1:10080

curl http://127.0.0.1:10080/secure

Cloud shell 2 - log in

curl -u user http://127.0.0.1:10080/login

curl -H "Authorization: Bearer <token>" http://127.0.0.1:10080/secure

View logs

kubectl logs monolith

kubectl logs -f monolith # realtime

In Cloud Shell 3

curl http://127.0.0.1:10080

In Cloud Shell 2

Exit log watching (Ctrl-C)

You can use the kubectl exec command to run an interactive shell inside the monolith Pod. This can come in handy when you want to troubleshoot from within a container:

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

For example, once we have a shell into the monolith container we can test external connectivity using the ping command.

ping -c 3 google.com

When you’re done with the interactive shell be sure to logout.

exit

MHC Overview

http://kubernetes.io/docs/user-guide/liveness/

apiVersion: v1
kind: Pod
metadata:
  name: "healthy-monolith"
  labels:
    app: monolith
spec:
  containers:
    - name: monolith
      image: udacity/example-monolith:1.0.0
      ports:
        - name: http
          containerPort: 80
        - name: health
          containerPort: 81
      resources:
        limits:
          cpu: 0.2
          memory: "10Mi"
      livenessProbe:
        httpGet:
          path: /healthz
          port: 81
          scheme: HTTP
        initialDelaySeconds: 5
        periodSeconds: 15
        timeoutSeconds: 5
      readinessProbe:
        httpGet:
          path: /readiness
          port: 81
          scheme: HTTP
        initialDelaySeconds: 5
        timeoutSeconds: 1

kubectl describe pods healthy-monolith | grep Readniess

# Readniess:

# http-get http://:81/readiness
# delay=5s
# timeout=1s
# period=10s

 

Secrets and Configmaps

Config docs - http://kubernetes.io/docs/user-guide/configmap/

Secrets - http://kubernetes.io/docs/user-guide/secrets/

ls tls

 ca-key.pem  ca.pem  cert.pem  key.pem  ssl-extensions-x509.cnf  update-tls.sh

The cert.pem and key.pem files will be used to secure traffic on the monolith server and the ca.pem will be used by HTTP clients as the CA to trust. Since the certs being used by the monolith server where signed by the CA represented by ca.pem, HTTP clients that trust ca.pem will be able to validate the SSL connection to the monolith server.

 

to create the tls-certs secret from the TLS certificates stored under the tls directory:

kubectl create secret generic tls-certs --from-file=tls/

kubectl will create a key for each file in the tls directory under the tls-certs secret bucket. Use the kubectl describe command to verify that:

kubectl describe secrets tls-certs

 

Name:         tls-certs
Namespace:    default
Labels:       <none>
Annotations:  <none>

Type:  Opaque

Data
====
ca.pem:                   1099 bytes
cert.pem:                 1253 bytes
key.pem:                  1679 bytes
ssl-extensions-x509.cnf:  275 bytes
update-tls.sh:            610 bytes
ca-key.pem:               1675 bytes

 

Next we need to create a configmap entry for the proxy.conf nginx configuration file using the kubectl create configmap command:

kubectl create configmap nginx-proxy-conf --from-file=nginx/proxy.conf

Use the kubectl describe configmap command to get more details about the nginx-proxy-conf configmap entry:

kubectl describe configmap nginx-proxy-conf

 Name:         nginx-proxy-conf
Namespace:    default
Labels:       <none>
Annotations:  <none>

Data
====
proxy.conf:
----
server {
  listen 443;
  ssl    on;

  ssl_certificate     /etc/tls/cert.pem;
  ssl_certificate_key /etc/tls/key.pem;

  location / {
    proxy_pass http://127.0.0.1:80;
  }
}

BinaryData
====

TLS and SSL can be confusing topics. Here’s a good primer for understanding the basics: https://en.wikipedia.org/wiki/Transport_Layer_Security

 

Accessing a Secure HTTPS Endpoint

cat pods/secure-monolith.yaml

apiVersion: v1
kind: Pod
metadata:
  name: "secure-monolith"
  labels:
    app: monolith
spec:
  containers:
    - name: nginx
      image: "nginx:1.9.14"
      lifecycle:
        preStop:
          exec:
            command: ["/usr/sbin/nginx","-s","quit"]
      volumeMounts:
        - name: "nginx-proxy-conf"
          mountPath: "/etc/nginx/conf.d"
        - name: "tls-certs"
          mountPath: "/etc/tls"
    - name: monolith
      image: "udacity/example-monolith:1.0.0"
      ports:
        - name: http
          containerPort: 80
        - name: health
          containerPort: 81
      resources:
        limits:
          cpu: 0.2
          memory: "10Mi"
      livenessProbe:
        httpGet:
          path: /healthz
          port: 81
          scheme: HTTP
        initialDelaySeconds: 5
        periodSeconds: 15
        timeoutSeconds: 5
      readinessProbe:
        httpGet:
          path: /readiness
          port: 81
          scheme: HTTP
        initialDelaySeconds: 5
        timeoutSeconds: 1
  volumes:
    - name: "tls-certs"
      secret:
        secretName: "tls-certs"
    - name: "nginx-proxy-conf"
      configMap:
        name: "nginx-proxy-conf"
        items:
          - key: "proxy.conf"
            path: "proxy.conf"

Create the secure-monolith Pod using kubectl.

kubectl create -f pods/secure-monolith.yaml
kubectl get pods secure-monolith

kubectl port-forward secure-monolith 10443:443

curl --cacert tls/ca.pem https://127.0.0.1:10443

kubectl logs -c nginx secure-monolith

 

 Services

https://kubernetes.io/docs/concepts/services-networking/service/

An abstract way to expose an application running on a set of Pods as a network service.

With Kubernetes you don't need to modify your application to use an unfamiliar service discovery mechanism. Kubernetes gives Pods their own IP addresses and a single DNS name for a set of Pods, and can load-balance across them.

kubectl create -f services/monolith.yaml

kind: Service
apiVersion: v1
metadata:
  name: "monolith"
spec:
  selector:
    app: "monolith"
    secure: "enabled"
  ports:
    - protocol: "TCP"
      port: 443
      targetPort: 443
      nodePort: 31000