gcloud container clusters create mycluster –zone europe-north1-a

After a while, it took me two and a half minutes, 3 virtual machines will be raised, the operating system is installed on them and the disk is mounted. Let's check:

esschtolts @ cloudshell: ~ (essch) $ gcloud container clusters list –filter = name = mycluster

NAME LOCATION MASTER_IP MACHINE_TYPE NODE_VERSION NUM_NODES STATUS

mycluster europe-north1-a 35.228.37.100 n1-standard-1 1.10.9-gke.5 3 RUNNING

esschtolts @ cloudshell: ~ (essch) $ gcloud compute instances list

NAME MACHINE_TYPE EXTERNAL_IP STATUS

gke-mycluster-default-pool-43710ef9-0168 n1-standard-1 35.228.73.217 RUNNING

gke-mycluster-default-pool-43710ef9-39ck n1-standard-1 35.228.75.47 RUNNING

gke-mycluster-default-pool-43710ef9-g76k n1-standard-1 35.228.117.209 RUNNING

Let's connect to the virtual machine:

esschtolts @ cloudshell: ~ (essch) $ gcloud projects list

PROJECT_ID NAME PROJECT_NUMBER

agile-aleph-203917 My First Project 546748042692

essch app 283762935665

esschtolts @ cloudshell: ~ (essch) $ gcloud container clusters get-credentials mycluster \

–-zone europe-north1-a \

–-project essch

Fetching cluster endpoint and auth data.

kubeconfig entry generated for mycluster.

We don't have a cluster yet:

esschtolts @ cloudshell: ~ (essch) $ kubectl get pods

No resources found.

Let's create a cluster:

esschtolts @ cloudshell: ~ (essch) $ kubectl run Nginx –image = Nginx –replicas = 3

deployment.apps "Nginx" created

Let's check its composition:

esschtolts @ cloudshell: ~ (essch) $ kubectl get deployments –selector = run = Nginx

NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE

Nginx 3 3 3 3 14s

esschtolts @ cloudshell: ~ (essch) $ kubectl get pods –selector = run = Nginx

NAME READY STATUS RESTARTS AGE

Nginx-65899c769f-9whdx 1/1 Running 0 43s

Nginx-65899c769f-szwtd 1/1 Running 0 43s

Nginx-65899c769f-zs6g5 1/1 Running 0 43s

Let's make sure that all three replicas of the cluster are distributed evenly across all three nodes:

esschtolts @ cloudshell: ~ (essch) $ kubectl describe pod Nginx-65899c769f-9whdx | grep Node:

Node: gke-mycluster-default-pool-43710ef9-g76k / 10.166.0.5

esschtolts @ cloudshell: ~ (essch) $ kubectl describe pod Nginx-65899c769f-szwtd | grep Node:

Node: gke-mycluster-default-pool-43710ef9-39ck / 10.166.0.4

esschtolts @ cloudshell: ~ (essch) $ kubectl describe pod Nginx-65899c769f-zs6g5 | grep Node:

Node: gke-mycluster-default-pool-43710ef9-g76k / 10.166.0.5

Now let's install the load balancer:

esschtolts @ cloudshell: ~ (essch) $ kubectl expose Deployment Nginx –type = "LoadBalancer" –port = 80

service "Nginx" exposed

Let's check that it was created:

esschtolts @ cloudshell: ~ (essch) $ kubectl expose Deployment Nginx –type = "LoadBalancer" –port = 80

service "Nginx" exposed

esschtolts @ cloudshell: ~ (essch) $ kubectl get svc –selector = run = Nginx

NAME TYPE CLUSTER-IP EXTERNAL-IP PORT (S) AGE

Nginx LoadBalancer 10.27.245.187 pending> 80: 31621 / TCP 11s

esschtolts @ cloudshell: ~ (essch) $ sleep 60;

esschtolts @ cloudshell: ~ (essch) $ kubectl get svc –selector = run = Nginx

NAME TYPE CLUSTER-IP EXTERNAL-IP PORT (S) AGE

Nginx LoadBalancer 10.27.245.187 35.228.212.163 80: 31621 / TCP 1m

Let's check its work:

esschtolts @ cloudshell: ~ (essch) $ curl 35.228.212.163:80 2> \ dev \ null | grep h1

Welcome to Nginx! </ h1>

In order not to copy the full names every time, save them in variables (more about the JSONpath format in the Go documentation: https://golang.org/pkg/text/template/#pkg-overview):

esschtolts @ cloudshell: ~ (essch) $ pod1 = $ (kubectl get pods -o jsonpath = {. items [0] .metadata.name});

esschtolts @ cloudshell: ~ (essch) $ pod2 = $ (kubectl get pods -o jsonpath = {. items [1] .metadata.name});

esschtolts @ cloudshell: ~ (essch) $ pod3 = $ (kubectl get pods -o jsonpath = {. items [2] .metadata.name});

esschtolts @ cloudshell: ~ (essch) $ echo $ pod1 $ pod2 $ pod3

Nginx-65899c769f-9whdx Nginx-65899c769f-szwtd Nginx-65899c769f-zs6g5

Let's change the pages in each POD by copying the unique pages to each replica, and check the balancing by checking the distribution of requests across the POD:

esschtolts @ cloudshell: ~ (essch) $ echo 1> test.html;

esschtolts @ cloudshell: ~ (essch) $ kubectl cp test.html $ {pod1}: / usr / share / Nginx / html / index.html

esschtolts @ cloudshell: ~ (essch) $ echo 2> test.html;

esschtolts @ cloudshell: ~ (essch) $ kubectl cp test.html $ {pod2}: / usr / share / Nginx / html / index.html

esschtolts @ cloudshell: ~ (essch) $ echo 3> test.html;

esschtolts @ cloudshell: ~ (essch) $ kubectl cp test.html $ {pod3}: / usr / share / Nginx / html / index.html

esschtolts @ cloudshell: ~ (essch) $ curl 35.228.212.163:80 && curl 35.228.212.163:80 && curl 35.228.212.163:80

3

2

one

esschtolts @ cloudshell: ~ (essch) $ curl 35.228.212.163:80 && curl 35.228.212.163:80 && curl 35.228.212.163:80

3

one

one

Let's check the failover of the cluster by deleting one POD:

esschtolts @ cloudshell: ~ (essch) $ kubectl delete pod $ {pod1} && kubectl get pods && sleep 10 && kubectl get pods

pod "Nginx-65899c769f-9whdx" deleted

NAME READY STATUS RESTARTS AGE

Nginx-65899c769f-42rd5 0/1 ContainerCreating 0 1s

Nginx-65899c769f-9whdx 0/1 Terminating 0 54m

Nginx-65899c769f-szwtd 1/1 Running 0 54m

Nginx-65899c769f-zs6g5 1/1 Running 0 54m

NAME READY STATUS RESTARTS AGE

Nginx-65899c769f-42rd5 1/1 Running 0 12s

Nginx-65899c769f-szwtd 1/1 Running 0 55m

Nginx-65899c769f-zs6g5 1/1 Running 0 55m

As we can see, immediately after the POD became unavailable (the process of deleting it began) its replacement began to be created. Soon, the cluster will fully restore its structure. After we have finished our experiments, remove the virtual machines with the cluster:

esschtolts @ cloudshell: ~ (essch) $ gcloud container clusters delete mycluster –zone europe-north1-a;

The following clusters will be deleted.

– [mycluster] in [europe-north1-a]

Do you want to continue (Y / n)? Y

Deleting cluster mycluster … done.

Deleted [https://container.googleapis.com/v1/projects/essch/zones/europe-north1-a/clusters/mycluster].

esschtolts @ cloudshell: ~ (essch) $ gcloud container clusters list –filter = name = mycluster

Total. We created a cluster and created a load balancer with just two run and expose commands, now we can go to the balancer's IP address and watch the NGINX welcome page in the browser. In this case, the cluster recovers itself, for this we emulated a failure of the pod by deleting it – it was created again.

Cluster Reproducibility

Let's take a look at the situation from the previous chapter, in which we created a cluster, deleted a replica, and it recovered. The fact is that we do not manage commands directly, but with the help of commands we create descriptions of the required configuration of the cluster and place it in the distributed storage, after which the state of the nodes is maintained in accordance with this description in the distributed storage. We can also get and edit these descriptions, or write ourselves and then upload them to a distributed storage. This will allow us to save the state on disk in the form of YAML files and restore it back, as is often done when moving from a production server to a test one. In addition, we get the opportunity to more flexibly customize the state, but since we are not limited to commands.

esschtolts @ cloudshell: ~ (essch) $ kubectl get deployment / Nginx –output = yaml