Početak rada s Kubernetesom na CentOS-u 7

Kubernetes je platforma otvorenog koda koju je razvio Google za upravljanje kontejnerskim aplikacijama na klasteru poslužitelja. Nadovezuje se na desetljeće i pol iskustva koje Google ima s pokretanjem klastera spremnika u velikom obimu i pruža razvojnim programerima infrastrukturu u stilu Googlea, koristeći najbolje projekte otvorenog koda, kao što su:

• Docker : tehnologija spremnika aplikacija.
• Etcd : distribuirana pohrana podataka ključ/vrijednost koja upravlja informacijama u cijelom klasteru i pruža otkrivanje usluge.
• Flannel : preklapajuća mrežna tkanina koja omogućuje povezivanje kontejnera na više poslužitelja.

Kubernetes omogućuje programerima da deklarativno definiraju svoju aplikacijsku infrastrukturu kroz YAML datoteke i apstrakcije kao što su podovi, RC-ovi i usluge (više o tome kasnije) i osigurava da se temeljni klaster u svakom trenutku podudara s korisnički definiranim stanjem.

Neke od njegovih značajki uključuju:

• Automatsko zakazivanje resursa sustava i automatsko postavljanje spremnika aplikacija u klaster.
• Skaliranje aplikacija u hodu jednom naredbom.
• Neprekidna ažuriranja bez zastoja.
• Samoizlječenje: automatsko reprogramiranje aplikacije ako poslužitelj ne uspije, automatsko ponovno pokretanje spremnika, provjere zdravlja.

Prijeđite na instalaciju ako ste već upoznati s Kubernetesom.

Osnovni koncepti

Kubernetes nudi programerima sljedeće apstrakcije (logičke jedinice):

• mahune.
• Kontrolori replikacije.
• Oznake.
• Usluge.

mahune

To je osnovna jedinica Kubernetes radnih opterećenja. Pod modelira "logički host" specifičan za aplikaciju u kontejnerskom okruženju. Laički rečeno, modelira grupu aplikacija ili usluga koje su se radile na istom poslužitelju u svijetu prije kontejnera. Spremnici unutar modula dijele isti mrežni prostor imena, a mogu dijeliti i količine podataka.

Kontrolori replikacije

Podovi su izvrsni za grupiranje više spremnika u logičke aplikacijske jedinice, ali ne nude replikaciju ili reprogramiranje u slučaju kvara poslužitelja.

Ovdje je zgodan kontroler replikacije ili RC. RC osigurava da se određeni broj podova dane usluge uvijek izvodi u klasteru.

Oznake

Oni su metapodaci ključ/vrijednost koji se mogu priložiti bilo kojem Kubernetes resursu (podovi, RC-ovi, usluge, čvorovi, ...).

Usluge

Podovi i kontroleri replikacije izvrsni su za implementaciju i distribuciju aplikacija u klasteru, ali podovi imaju efemerne IP-ove koji se mijenjaju nakon ponovnog rasporeda ili ponovnog pokretanja spremnika.

Usluga Kubernetes pruža stabilnu krajnju točku (fiksni virtualni IP + vezanje porta za host poslužitelje) za grupu podova kojima upravlja kontroler replikacije.

Kubernetes klaster

U svom najjednostavnijem obliku, Kubernetes klaster se sastoji od dvije vrste čvorova:

• 1 Kubernetes majstor.
• N čvorova Kubernetes.

Kubernetes majstor

Kubernetes master je kontrolna jedinica cijelog klastera.

Glavne komponente majstora su:

• Etcd: globalno dostupno skladište podataka koje pohranjuje informacije o klasteru te uslugama i aplikacijama koje se izvode na klasteru.
• Kube API poslužitelj: ovo je glavno upravljačko središte Kubernetes klastera i izlaže RESTful sučelje.
• Upravitelj kontrolera: upravlja replikacijom aplikacija kojima upravljaju kontroleri replikacije.
• Planer: prati korištenje resursa u cijelom klasteru i u skladu s tim dodjeljuje radna opterećenja.

Kubernetes čvor

Kubernetes čvor su radni poslužitelji koji su odgovorni za pokretanje podova.

Glavne komponente čvora su:

• Docker: demon koji pokreće aplikacijske kontejnere definirane u podovima.
• Kubelet: kontrolna jedinica za mahune u lokalnom sustavu.
• Kube-proxy: mrežni proxy koji osigurava ispravno usmjeravanje za Kubernetes usluge.

Montaža

U ovom vodiču kreirat ćemo klaster s 3 čvora koristeći CentOS 7 poslužitelje:

• 1 Kubernetes master (kube-master)
• 2 Kubernetes čvora (kube-čvor1, kube-čvor2)

Kasnije možete dodati onoliko dodatnih čvorova koliko želite slijedeći isti postupak instalacije za Kubernetes čvorove.

Svi čvorovi

Konfigurirajte imena hosta i /etc/hosts:

# /etc/hostname
kube-master
# or kube-node1, kube-node2

# append to /etc/hosts
replace-with-master-server-ip kube-master
replace-with-node1-ip kube-node1
replace-with-node2-ip kube-node2

Onemogući firewalld:

systemctl disable firewalld
systemctl stop firewalld

Kubernetes majstor

Instalirajte Kubernetes master pakete:

yum install etcd kubernetes-master

Konfiguracija:

# /etc/etcd/etcd.conf
# leave rest of the lines unchanged
ETCD_LISTEN_CLIENT_URLS="http://0.0.0.0:2379"
ETCD_LISTEN_PEER_URLS="http://localhost:2380"
ETCD_ADVERTISE_CLIENT_URLS="http://0.0.0.0:2379"

# /etc/kubernetes/config
# leave rest of the lines unchanged
KUBE_MASTER="--master=http://kube-master:8080"

# /etc/kubernetes/apiserver
# leave rest of the lines unchanged
KUBE_API_ADDRESS="--address=0.0.0.0"
KUBE_ETCD_SERVERS="--etcd_servers=http://kube-master:2379"

Pokreni itd.:

systemctl start etcd

Instalirajte i konfigurirajte Flannel overlay mrežnu strukturu (ovo je potrebno kako bi se spremnici koji rade na različitim poslužiteljima mogli vidjeti jedni druge):

yum install flannel

Napravite konfiguracijsku datoteku Flanel ( flannel-config.json):

{
  "Network": "10.20.0.0/16",
  "SubnetLen": 24,
  "Backend": {
    "Type": "vxlan",
    "VNI": 1
  }  
}

Postavite Flannel konfiguraciju na Etcd poslužitelju:

etcdctl set coreos.com/network/config < flannel-config.json

Usmjerite Flannel na Etcd poslužitelj:

# /etc/sysconfig/flanneld
FLANNEL_ETCD="http://kube-master:2379"

Omogućite usluge tako da počnu pri pokretanju:

systemctl enable etcd
systemctl enable kube-apiserver
systemctl enable kube-controller-manager
systemctl enable kube-scheduler
systemctl enable flanneld

Ponovno pokrenite poslužitelj.

Kubernetes čvor

Instalirajte Kubernetes čvorne pakete:

yum install docker kubernetes-node

Sljedeća dva koraka će konfigurirati Docker da koristi overlayfs za bolju izvedbu. Za više informacija posjetite ovaj blog post :

Izbrišite trenutni docker direktorij za pohranu:

systemctl stop docker
rm -rf /var/lib/docker

Promjena konfiguracijskih datoteka:

# /etc/sysconfig/docker
# leave rest of lines unchanged
OPTIONS='--selinux-enabled=false'

# /etc/sysconfig/docker
# leave rest of lines unchanged
DOCKER_STORAGE_OPTIONS=-s overlay

Konfigurirajte kube-node1 da koristi naš prethodno konfigurirani master:

# /etc/kubernetes/config
# leave rest of lines unchanged
KUBE_MASTER="--master=http://kube-master:8080"

# /etc/kubernetes/kubelet
# leave rest of the lines unchanged
KUBELET_ADDRESS="--address=0.0.0.0"
# comment this line, so that the actual hostname is used to register the node
# KUBELET_HOSTNAME="--hostname_override=127.0.0.1"
KUBELET_API_SERVER="--api_servers=http://kube-master:8080"

Instalirajte i konfigurirajte Flannel overlay mrežnu tkaninu (opet - ovo je potrebno kako bi se spremnici koji rade na različitim poslužiteljima mogli vidjeti jedni druge):

yum install flannel

Usmjerite Flannel na Etcd poslužitelj:

# /etc/sysconfig/flanneld
FLANNEL_ETCD="http://kube-master:2379"

Omogući usluge:

systemctl enable docker
systemctl enable flanneld
systemctl enable kubelet
systemctl enable kube-proxy

Ponovno pokrenite poslužitelj.

Testirajte svoj Kubernetes poslužitelj

Nakon što se svi poslužitelji ponovno pokrenu, provjerite radi li vaš Kubernetes klaster:

[root@kube-master ~]# kubectl get nodes
NAME         LABELS                              STATUS
kube-node1   kubernetes.io/hostname=kube-node1   Ready
kube-node2   kubernetes.io/hostname=kube-node2   Ready

Primjer: postavljanje Selenium mreže pomoću Kubernetesa

Selenium je okvir za automatizaciju preglednika za potrebe testiranja. To je moćan alat iz arsenala bilo kojeg web developera.

Selenium grid omogućuje skalabilno i paralelno daljinsko izvođenje testova u klasteru Selenium čvorova koji su povezani sa središnjim Selenium čvorištem.

Since Selenium nodes are stateless themselves and the amount of nodes we run is flexible, depending on our testing workloads, this is a perfect candidate application to be deployed on a Kubernetes cluster.

In the next section, we'll deploy a grid consisting of 5 application containers:

• 1 central Selenium hub that will be the remote endpoint to which our tests will connect.
• 2 Selenium nodes running Firefox.
• 2 Selenium nodes running Chrome.

Deployment strategy

To automatically manage replication and self-healing, we'll create a Kubernetes replication controller for each type of application container we listed above.

To provide developers who are running tests with a stable Selenium hub endpoint, we'll create a Kubernetes service connected to the hub replication controller.

Selenium hub

Replication controller

# selenium-hub-rc.yaml
apiVersion: v1
kind: ReplicationController
metadata:
  name: selenium-hub
spec:
  replicas: 1
  selector:
    name: selenium-hub
  template:
    metadata:
      labels:
        name: selenium-hub
    spec:
      containers:
        - name: selenium-hub
          image: selenium/hub
          ports:
            - containerPort: 4444

Deployment:

[root@kube-master ~]# kubectl create -f selenium-hub-rc.yaml
replicationcontrollers/selenium-hub
[root@kube-master ~]# kubectl get rc
CONTROLLER     CONTAINER(S)   IMAGE(S)       SELECTOR            REPLICAS
selenium-hub   selenium-hub   selenium/hub   name=selenium-hub   1
[root@kube-master ~]# kubectl get pods
NAME                 READY     STATUS    RESTARTS   AGE
selenium-hub-pilc8   1/1       Running   0          50s
[root@kube-master ~]# kubectl describe pod selenium-hub-pilc8
Name:               selenium-hub-pilc8
Namespace:          default
Image(s):           selenium/hub
Node:               kube-node2/45.63.16.92
Labels:             name=selenium-hub
Status:             Running
Reason:             
Message:            
IP:             10.20.101.2
Replication Controllers:    selenium-hub (1/1 replicas created)
Containers:
  selenium-hub:
    Image:      selenium/hub
    State:      Running
      Started:      Sat, 24 Oct 2015 16:01:39 +0000
    Ready:      True
    Restart Count:  0
Conditions:
  Type      Status
  Ready     True
Events:
  FirstSeen             LastSeen            Count   From            SubobjectPath               Reason      Message
  Sat, 24 Oct 2015 16:01:02 +0000   Sat, 24 Oct 2015 16:01:02 +0000 1   {scheduler }                            scheduled   Successfully assigned selenium-hub-pilc8 to kube-node2
  Sat, 24 Oct 2015 16:01:05 +0000   Sat, 24 Oct 2015 16:01:05 +0000 1   {kubelet kube-node2}    implicitly required container POD   pulled      Successfully pulled Pod container image "gcr.io/google_containers/pause:0.8.0"
  Sat, 24 Oct 2015 16:01:05 +0000   Sat, 24 Oct 2015 16:01:05 +0000 1   {kubelet kube-node2}    implicitly required container POD   created     Created with docker id 6de00106b19c
  Sat, 24 Oct 2015 16:01:05 +0000   Sat, 24 Oct 2015 16:01:05 +0000 1   {kubelet kube-node2}    implicitly required container POD   started     Started with docker id 6de00106b19c
  Sat, 24 Oct 2015 16:01:39 +0000   Sat, 24 Oct 2015 16:01:39 +0000 1   {kubelet kube-node2}    spec.containers     pulled      Successfully pulled image "selenium/hub"
  Sat, 24 Oct 2015 16:01:39 +0000   Sat, 24 Oct 2015 16:01:39 +0000 1   {kubelet kube-node2}    spec.containers     created     Created with docker id 7583cc09268c
  Sat, 24 Oct 2015 16:01:39 +0000   Sat, 24 Oct 2015 16:01:39 +0000 1   {kubelet kube-node2}    spec.containers     started     Started with docker id 7583cc09268c

Ovdje možemo vidjeti da je Kubernetes postavio moj selen-hub kontejner na kube-node2.

Servis

# selenium-hub-service.yaml
apiVersion: v1
kind: Service
metadata:
  name: selenium-hub
spec:
  type: NodePort
  ports:
  - port: 4444
    protocol: TCP
    nodePort: 30000
  selector:
    name: selenium-hub

implementacija:

[root@kube-master ~]# kubectl create -f selenium-hub-service.yaml
You have exposed your service on an external port on all nodes in your
cluster.  If you want to expose this service to the external internet, you may
need to set up firewall rules for the service port(s) (tcp:30000) to serve traffic.

See http://releases.k8s.io/HEAD/docs/user-guide/services-firewalls.md for more details.
services/selenium-hub
[root@kube-master ~]# kubectl get services
NAME           LABELS                                    SELECTOR            IP(S)           PORT(S)
kubernetes     component=apiserver,provider=kubernetes   <none>              10.254.0.1      443/TCP
selenium-hub   <none>                                    name=selenium-hub   10.254.124.73   4444/TCP

Nakon implementacije usluge, bit će dostupna sa:

• Bilo koji Kubernetes čvor, preko virtualnog IP-a 10.254.124.73 i porta 4444.
• Vanjske mreže, putem javnih IP-ova bilo kojeg Kubernetes čvora, na portu 30000.

(koristeći javni IP drugog Kubernetes čvora)

Selenski čvorovi

Kontroler replikacije čvora Firefox:

# selenium-node-firefox-rc.yaml
apiVersion: v1
kind: ReplicationController
metadata:
  name: selenium-node-firefox
spec:
  replicas: 2
  selector:
    name: selenium-node-firefox
  template:
    metadata:
      labels:
        name: selenium-node-firefox
    spec:
      containers:
        - name: selenium-node-firefox
          image: selenium/node-firefox
          ports:
            - containerPort: 5900
          env:
            - name: HUB_PORT_4444_TCP_ADDR
              value: "replace_with_service_ip"
            - name: HUB_PORT_4444_TCP_PORT
              value: "4444"

implementacija:

Zamijenite replace_with_service_ipu selenium-node-firefox-rc.yamlsa stvarnim Selen koncentrator IP usluga, u ovom slučaju 10.254.124.73.

[root@kube-master ~]# kubectl create -f selenium-node-firefox-rc.yaml
replicationcontrollers/selenium-node-firefox

[root@kube-master ~]# kubectl get rc
CONTROLLER              CONTAINER(S)            IMAGE(S)                SELECTOR                     REPLICAS
selenium-hub            selenium-hub            selenium/hub            name=selenium-hub            1
selenium-node-firefox   selenium-node-firefox   selenium/node-firefox   name=selenium-node-firefox   2

[root@kube-master ~]# kubectl get pods
NAME                          READY     STATUS    RESTARTS   AGE
selenium-hub-pilc8            1/1       Running   1          1h
selenium-node-firefox-lc6qt   1/1       Running   0          2m
selenium-node-firefox-y9qjp   1/1       Running   0          2m

[root@kube-master ~]# kubectl describe pod selenium-node-firefox-lc6qt
Name:               selenium-node-firefox-lc6qt
Namespace:          default
Image(s):           selenium/node-firefox
Node:               kube-node2/45.63.16.92
Labels:             name=selenium-node-firefox
Status:             Running
Reason:             
Message:            
IP:             10.20.101.3
Replication Controllers:    selenium-node-firefox (2/2 replicas created)
Containers:
  selenium-node-firefox:
    Image:      selenium/node-firefox
    State:      Running
      Started:      Sat, 24 Oct 2015 17:08:37 +0000
    Ready:      True
    Restart Count:  0
Conditions:
  Type      Status
  Ready     True
Events:
  FirstSeen             LastSeen            Count   From            SubobjectPath               Reason      Message
  Sat, 24 Oct 2015 17:08:13 +0000   Sat, 24 Oct 2015 17:08:13 +0000 1   {scheduler }                            scheduled   Successfully assigned selenium-node-firefox-lc6qt to kube-node2
  Sat, 24 Oct 2015 17:08:13 +0000   Sat, 24 Oct 2015 17:08:13 +0000 1   {kubelet kube-node2}    implicitly required container POD   pulled      Pod container image "gcr.io/google_containers/pause:0.8.0" already present on machine
  Sat, 24 Oct 2015 17:08:13 +0000   Sat, 24 Oct 2015 17:08:13 +0000 1   {kubelet kube-node2}    implicitly required container POD   created     Created with docker id cdcb027c6548
  Sat, 24 Oct 2015 17:08:13 +0000   Sat, 24 Oct 2015 17:08:13 +0000 1   {kubelet kube-node2}    implicitly required container POD   started     Started with docker id cdcb027c6548
  Sat, 24 Oct 2015 17:08:36 +0000   Sat, 24 Oct 2015 17:08:36 +0000 1   {kubelet kube-node2}    spec.containers pulled      Successfully pulled image "selenium/node-firefox"
  Sat, 24 Oct 2015 17:08:36 +0000   Sat, 24 Oct 2015 17:08:36 +0000 1   {kubelet kube-node2}    spec.containers created     Created with docker id 8931b7f7a818
  Sat, 24 Oct 2015 17:08:37 +0000   Sat, 24 Oct 2015 17:08:37 +0000 1   {kubelet kube-node2}    spec.containers started     Started with docker id 8931b7f7a818

[root@kube-master ~]# kubectl describe pod selenium-node-firefox-y9qjp
Name:               selenium-node-firefox-y9qjp
Namespace:          default
Image(s):           selenium/node-firefox
Node:               kube-node1/185.92.221.67
Labels:             name=selenium-node-firefox
Status:             Running
Reason:             
Message:            
IP:             10.20.92.3
Replication Controllers:    selenium-node-firefox (2/2 replicas created)
Containers:
  selenium-node-firefox:
    Image:      selenium/node-firefox
    State:      Running
      Started:      Sat, 24 Oct 2015 17:08:13 +0000
    Ready:      True
    Restart Count:  0
Conditions:
  Type      Status
  Ready     True
Events:
  FirstSeen             LastSeen            Count   From            SubobjectPath               Reason      Message
  Sat, 24 Oct 2015 17:08:13 +0000   Sat, 24 Oct 2015 17:08:13 +0000 1   {scheduler }                            scheduled   Successfully assigned selenium-node-firefox-y9qjp to kube-node1
  Sat, 24 Oct 2015 17:08:13 +0000   Sat, 24 Oct 2015 17:08:13 +0000 1   {kubelet kube-node1}    implicitly required container POD   pulled      Pod container image "gcr.io/google_containers/pause:0.8.0" already present on machine
  Sat, 24 Oct 2015 17:08:13 +0000   Sat, 24 Oct 2015 17:08:13 +0000 1   {kubelet kube-node1}    implicitly required container POD   created     Created with docker id ea272dd36bd5
  Sat, 24 Oct 2015 17:08:13 +0000   Sat, 24 Oct 2015 17:08:13 +0000 1   {kubelet kube-node1}    implicitly required container POD   started     Started with docker id ea272dd36bd5
  Sat, 24 Oct 2015 17:08:13 +0000   Sat, 24 Oct 2015 17:08:13 +0000 1   {kubelet kube-node1}    spec.containers created     Created with docker id 6edbd6b9861d
  Sat, 24 Oct 2015 17:08:13 +0000   Sat, 24 Oct 2015 17:08:13 +0000 1   {kubelet kube-node1}    spec.containers started     Started with docker id 6edbd6b9861d

Kao što vidimo, Kubernetes je napravio 2 replike selenium-firefox-nodei distribuirao ih po cijelom klasteru. Pod selenium-node-firefox-lc6qtje na kube-čvoru2, dok je pod selenium-node-firefox-y9qjpna kube-čvoru1.

Ponavljamo isti postupak za naše Selenium Chrome čvorove.

Kontroler replikacije čvora Chrome:

# selenium-node-chrome-rc.yaml
apiVersion: v1
kind: ReplicationController
metadata:
  name: selenium-node-chrome
  labels:
    app: selenium-node-chrome
spec:
  replicas: 2
  selector:
    app: selenium-node-chrome
  template:
    metadata:
      labels:
        app: selenium-node-chrome
    spec:
      containers:
      - name: selenium-node-chrome
        image: selenium/node-chrome
        ports:
          - containerPort: 5900
        env:
          - name: HUB_PORT_4444_TCP_ADDR
            value: "replace_with_service_ip"
          - name: HUB_PORT_4444_TCP_PORT
            value: "4444"

implementacija:

[root@kube-master ~]# kubectl create -f selenium-node-chrome-rc.yaml
replicationcontrollers/selenium-node-chrome
[root@kube-master ~]# kubectl get rc
CONTROLLER              CONTAINER(S)            IMAGE(S)                SELECTOR                     REPLICAS
selenium-hub            selenium-hub            selenium/hub            name=selenium-hub            1
selenium-node-chrome    selenium-node-chrome    selenium/node-chrome    app=selenium-node-chrome     2
selenium-node-firefox   selenium-node-firefox   selenium/node-firefox   name=selenium-node-firefox   2
[root@kube-master ~]# kubectl get pods
NAME                          READY     STATUS    RESTARTS   AGE
selenium-hub-pilc8            1/1       Running   1          1h
selenium-node-chrome-9u1ld    1/1       Running   0          1m
selenium-node-chrome-mgi52    1/1       Running   0          1m
selenium-node-firefox-lc6qt   1/1       Running   0          11m
selenium-node-firefox-y9qjp   1/1       Running   0          11m

Završavati

U ovom vodiču postavili smo mali Kubernetes klaster od 3 poslužitelja (1 glavni kontroler + 2 radnika).

Koristeći podove, RC-ove i uslugu, uspješno smo implementirali Selenium Grid koji se sastoji od središnjeg čvorišta i 4 čvora, omogućujući programerima da istovremeno pokreću 4 Selenium testa na klasteru.

Kubernetes je automatski rasporedio spremnike u cijelom klasteru.

Samoizlječenje

Kubernetes automatski reprogramira podove na zdrave poslužitelje ako se jedan ili više naših poslužitelja pokvari. U mom primjeru, kube-node2 trenutno pokreće Selenium hub pod i 1 Selenium Firefox node pod.

[root@kube-node2 ~]# docker ps
CONTAINER ID        IMAGE                                  COMMAND                CREATED             STATUS              PORTS               NAMES
5617399f146c        selenium/node-firefox                  "/opt/bin/entry_poin   5 minutes ago       Up 5 minutes                            k8s_selenium-node-firefox.46e635d8_selenium-node-firefox-zmj1r_default_31c89517-7a75-11e5-8648-5600001611e0_baae8e00   
185230a3b431        gcr.io/google_containers/pause:0.8.0   "/pause"               5 minutes ago       Up 5 minutes                            k8s_POD.3805e8b7_selenium-node-firefox-zmj1r_default_31c89517-7a75-11e5-8648-5600001611e0_40f809df                     
fdd5834c249d        selenium/hub                           "/opt/bin/entry_poin   About an hour ago   Up About an hour                        k8s_selenium-hub.cb8bf0ed_selenium-hub-pilc8_default_6c98c1ff-7a68-11e5-8648-5600001611e0_5765e2c9                     
00e4ccb0bda8        gcr.io/google_containers/pause:0.8.0   "/pause"               About an hour ago   Up About an hour                        k8s_POD.3b3ee8b9_selenium-hub-pilc8_default_6c98c1ff-7a68-11e5-8648-5600001611e0_8398ac33  

Simulirati ćemo neuspjeh poslužitelja gašenjem kube-node2. Nakon nekoliko minuta, trebali biste vidjeti da su spremnici koji su radili na kube-node2 preraspoređeni na kube-node1, osiguravajući minimalan prekid usluge.

[root@kube-node1 ~]# docker ps
CONTAINER ID        IMAGE                                  COMMAND                CREATED             STATUS              PORTS               NAMES
5bad5f582698        selenium/hub                           "/opt/bin/entry_poin   19 minutes ago      Up 19 minutes                           k8s_selenium-hub.cb8bf0ed_selenium-hub-hycf2_default_fe9057cf-7a76-11e5-8648-5600001611e0_ccaad50a                     
dd1565a94919        selenium/node-firefox                  "/opt/bin/entry_poin   20 minutes ago      Up 20 minutes                           k8s_selenium-node-firefox.46e635d8_selenium-node-firefox-g28z5_default_fe932673-7a76-11e5-8648-5600001611e0_fc79f977   
2be1a316aa47        gcr.io/google_containers/pause:0.8.0   "/pause"               20 minutes ago      Up 20 minutes                           k8s_POD.3805e8b7_selenium-node-firefox-g28z5_default_fe932673-7a76-11e5-8648-5600001611e0_dc204ad2                     
da75a0242a9e        gcr.io/google_containers/pause:0.8.0   "/pause"               20 minutes ago      Up 20 minutes                           k8s_POD.3b3ee8b9_selenium-hub-hycf2_default_fe9057cf-7a76-11e5-8648-5600001611e0_1b10c0e7                              
c611b68330de        selenium/node-firefox                  "/opt/bin/entry_poin   33 minutes ago      Up 33 minutes                           k8s_selenium-node-firefox.46e635d8_selenium-node-firefox-8ylo2_default_31c8a8f3-7a75-11e5-8648-5600001611e0_922af821   
828031da6b3c        gcr.io/google_containers/pause:0.8.0   "/pause"               33 minutes ago      Up 33 minutes                           k8s_POD.3805e8b7_selenium-node-firefox-8ylo2_default_31c8a8f3-7a75-11e5-8648-5600001611e0_289cd555                     
caf4e725512e        selenium/node-chrome                   "/opt/bin/entry_poin   46 minutes ago      Up 46 minutes                           k8s_selenium-node-chrome.362a34ee_selenium-node-chrome-mgi52_default_392a2647-7a73-11e5-8648-5600001611e0_3c6e855a     
409a20770787        selenium/node-chrome                   "/opt/bin/entry_poin   46 minutes ago      Up 46 minutes                           k8s_selenium-node-chrome.362a34ee_selenium-node-chrome-9u1ld_default_392a15a4-7a73-11e5-8648-5600001611e0_ac3f0191     
7e2d942422a5        gcr.io/google_containers/pause:0.8.0   "/pause"               47 minutes ago      Up 47 minutes                           k8s_POD.3805e8b7_selenium-node-chrome-9u1ld_default_392a15a4-7a73-11e5-8648-5600001611e0_f5858b73                      
a3a65ea99a99        gcr.io/google_containers/pause:0.8.0   "/pause"               47 minutes ago      Up 47 minutes                           k8s_POD.3805e8b7_selenium-node-chrome-mgi52_default_392a2647-7a73-11e5-8648-5600001611e0_20a70ab6

Skaliranje vaše Selenium Grid

Skaliranje vaše Selenium Grid je super jednostavno uz Kubernetes. Zamislite da bih umjesto 2 Firefox čvora želio pokrenuti 4. Povećanje se može izvršiti jednom naredbom:

[root@kube-master ~]# kubectl scale rc selenium-node-firefox --replicas=4
scaled

[root@kube-master ~]# kubectl get rc
CONTROLLER              CONTAINER(S)            IMAGE(S)                SELECTOR                     REPLICAS
selenium-hub            selenium-hub            selenium/hub            name=selenium-hub            1
selenium-node-chrome    selenium-node-chrome    selenium/node-chrome    app=selenium-node-chrome     2
selenium-node-firefox   selenium-node-firefox   selenium/node-firefox   name=selenium-node-firefox   4

[root@kube-master ~]# kubectl get pods
NAME                          READY     STATUS    RESTARTS   AGE
selenium-hub-pilc8            1/1       Running   1          1h
selenium-node-chrome-9u1ld    1/1       Running   0          14m
selenium-node-chrome-mgi52    1/1       Running   0          14m
selenium-node-firefox-8ylo2   1/1       Running   0          40s
selenium-node-firefox-lc6qt   1/1       Running   0          24m
selenium-node-firefox-y9qjp   1/1       Running   0          24m
selenium-node-firefox-zmj1r   1/1       Running   0          40s