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
<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)
