🥇Minimum Viable Kubernetes | Pulogalamu ya ProHoster

Kumasulira kwa nkhaniyi kunakonzedwa madzulo a chiyambi cha maphunziro "Zochita ndi zida za DevOps".

Ngati mukuwerenga izi, mwina mwamvapo za Kubernetes (ndipo ngati sichoncho, munafika bwanji kuno?) Koma kodi Kubernetes ndi chiyani kwenikweni? Izi "Orchestration of industrial-grade containers"? Kapena "Cloud-Native Operating System"? Kodi izi zikutanthauza chiyani?

Kunena zowona, sindiri wotsimikiza 100%. Koma ndikuganiza kuti ndizosangalatsa kukumba zamkati ndikuwona zomwe zikuchitika ku Kubernetes pansi pazigawo zake zambiri. Chifukwa chake kungosangalala, tiyeni tiwone momwe gulu laling'ono la "Kubernetes" limawonekera. (Izi zidzakhala zosavuta kuposa Kubernetes The Hard Way.)

Ndikuganiza kuti mumadziwa zambiri za Kubernetes, Linux, ndi zotengera. Chilichonse chomwe tikukamba pano ndi cha kafukufuku/zolinga zophunzirira zokha, osayika chilichonse pakupanga!

mwachidule

Kubernetes ili ndi zigawo zambiri. Malinga ndi Wikipedia, zomangamanga zimawoneka motere:

Pali zigawo zisanu ndi zitatu zomwe zikuwonetsedwa pano, koma sitinyalanyaza zambiri. Ndikufuna kunena kuti chinthu chochepa chomwe chitha kutchedwa Kubernetes chili ndi zigawo zitatu zazikulu:

cubelet
kube-apiserver (zomwe zimatengera etcd - database yake)
nthawi yogwiritsira ntchito chidebe (Docker pakadali pano)

Tiyeni tiwone zomwe zolembedwazo zimanena za aliyense wa iwo (rus., Chingerezi.). Poyamba cubelet:

Wothandizira akuyenda pa mfundo iliyonse pagulu. Zimatsimikizira kuti zotengera zikuyenda mu pod.

Zikumveka zosavuta mokwanira. Nanga bwanji nthawi ya kontena (chotengera nthawi yothamanga)?

Kuthamanga kwa chidebe ndi pulogalamu yopangidwa kuti iziyendetsa zotengera.

Zodziwitsa kwambiri. Koma ngati mumadziwa Docker, ndiye kuti muyenera kukhala ndi lingaliro lazomwe amachita. (Zambiri zakulekanitsidwa kwa maudindo pakati pa nthawi yoyendetsera chidebe ndi kubelet ndizowoneka bwino ndipo sindilowa nazo pano.)

И API seva?

API Server ndi gawo lowongolera la Kubernetes lomwe limawululira Kubernetes API. Seva ya API ndiye gawo la kasitomala la gulu lowongolera la Kubernetes

Aliyense amene adachitapo chilichonse ndi Kubernetes adalumikizana ndi API mwachindunji kapena kudzera kubectl. Uwu ndiye mtima wa zomwe zimapangitsa Kubernetes Kubernetes - ubongo womwe umasintha mapiri a YAML omwe tonse timawadziwa komanso kuwakonda (?) kukhala maziko ogwirira ntchito. Zikuwoneka zodziwikiratu kuti API iyenera kupezeka pamasinthidwe athu ochepa.

Zowonongeka

Makina enieni a Linux kapena akuthupi okhala ndi mizu (ndikugwiritsa ntchito Ubuntu 18.04 pamakina enieni).
Ndipo ndizo zonse!

Wotopetsa unsembe

Tiyenera kukhazikitsa Docker pamakina omwe tidzagwiritse ntchito. (Sindifotokoza mwatsatanetsatane momwe Docker ndi zotengera zimagwirira ntchito; ngati mukufuna, pali nkhani zodabwitsa). Tiyeni tingoyiyika nayo apt:

$ sudo apt install docker.io
$ sudo systemctl start docker

Pambuyo pake, tifunika kupeza ma binaries a Kubernetes. M'malo mwake, pakuyambitsa koyambirira kwa "cluster" yathu timangofunikira kubelet, popeza kuyendetsa zigawo zina za seva zomwe tingagwiritse ntchito kubelet. Kuti tigwirizane ndi gulu lathu litatha, tidzagwiritsanso ntchito kubectl.

$ curl -L https://dl.k8s.io/v1.18.5/kubernetes-server-linux-amd64.tar.gz > server.tar.gz
$ tar xzvf server.tar.gz
$ cp kubernetes/server/bin/kubelet .
$ cp kubernetes/server/bin/kubectl .
$ ./kubelet --version
Kubernetes v1.18.5

Chimachitika ndi chiyani tikangothamanga kubelet?

$ ./kubelet
F0609 04:03:29.105194    4583 server.go:254] mkdir /var/lib/kubelet: permission denied

kubelet iyenera kuyenda ngati mizu. Zomveka bwino, chifukwa amayenera kuyang'anira node yonse. Tiyeni tiwone magawo ake:

$ ./kubelet -h
<слишком много строк, чтобы разместить здесь>
$ ./kubelet -h | wc -l
284

Wow, zosankha zambiri! Mwamwayi, timangofunikira angapo a iwo. Nayi imodzi mwamagawo omwe timakonda:

--pod-manifest-path string

Njira yopita ku chikwatu chomwe chili ndi mafayilo a static pods, kapena njira yopita ku fayilo yofotokoza ma static pod. Mafayilo oyambira ndi madontho sanyalanyazidwa. (KUSINTHA: Njira iyi iyenera kukhazikitsidwa mufayilo yosinthira yomwe idaperekedwa ku Kubelet kudzera pa --config. Kuti mudziwe zambiri, onani kubernetes.io/docs/tasks/administer-cluster/kubelet-config-file .)

Njirayi imatithandiza kuthamanga static pods - ma pod omwe samayendetsedwa kudzera pa Kubernetes API. Madontho osasunthika sagwiritsidwa ntchito kawirikawiri, koma ndi osavuta kukweza gulu mwachangu, ndipo izi ndi zomwe timafunikira. Tidzanyalanyaza chenjezo lalikululi (kachiwiri, musayendetse izi popanga!)

Choyamba tipanga chikwatu cha ma static pods ndikuyendetsa kubelet:

$ mkdir pods
$ sudo ./kubelet --pod-manifest-path=pods

Kenako, pawindo lina/tmux/chilichonse, tidzapanga chiwonetsero cha pod:

$ cat <<EOF > pods/hello.yaml
apiVersion: v1
kind: Pod
metadata:
  name: hello
spec:
  containers:
  - image: busybox
    name: hello
    command: ["echo", "hello world!"]
EOF

kubelet amayamba kulemba machenjezo ndipo zikuwoneka ngati palibe chomwe chikuchitika. Koma zimenezo si zoona! Tiyeni tiwone Docker:

$ sudo docker ps -a
CONTAINER ID        IMAGE                  COMMAND                 CREATED             STATUS                      PORTS               NAMES
8c8a35e26663        busybox                "echo 'hello world!'"   36 seconds ago      Exited (0) 36 seconds ago                       k8s_hello_hello-mink8s_default_ab61ef0307c6e0dee2ab05dc1ff94812_4
68f670c3c85f        k8s.gcr.io/pause:3.2   "/pause"                2 minutes ago       Up 2 minutes                                    k8s_POD_hello-mink8s_default_ab61ef0307c6e0dee2ab05dc1ff94812_0
$ sudo docker logs k8s_hello_hello-mink8s_default_ab61ef0307c6e0dee2ab05dc1ff94812_4
hello world!

kubelet Ndidawerenga chiwonetsero cha pod ndikupatsa a Docker kuti akhazikitse zotengera zingapo malinga ndi zomwe tikufuna. (Ngati mukuganiza za chidebe cha "pause", ndi Kubernetes kuthyolako - onani blog iyi.) Kubelela kulakonzya kutugwasya busybox ndi lamulo lotchulidwa ndipo adzayambitsanso mpaka kalekale mpaka static pod ichotsedwa.

Dziyamikireni nokha. Tangobwera ndi imodzi mwa njira zosokoneza kwambiri zotulutsira mawu ku terminal!

Launch etcd

Cholinga chathu chachikulu ndikuyendetsa Kubernetes API, koma kuti tichite zimenezo choyamba tiyenera kuthamanga etcd. Tiyeni tiyambe gulu laling'ono la etcd poyika zoikamo zake mu bukhu la pods (mwachitsanzo, pods/etcd.yaml):

apiVersion: v1
kind: Pod
metadata:
  name: etcd
  namespace: kube-system
spec:
  containers:
  - name: etcd
    command:
    - etcd
    - --data-dir=/var/lib/etcd
    image: k8s.gcr.io/etcd:3.4.3-0
    volumeMounts:
    - mountPath: /var/lib/etcd
      name: etcd-data
  hostNetwork: true
  volumes:
  - hostPath:
      path: /var/lib/etcd
      type: DirectoryOrCreate
    name: etcd-data

Ngati mudagwirapo ntchito ndi Kubernetes, mafayilo awa a YAML ayenera kukhala odziwika kwa inu. Pali mfundo ziwiri zokha zofunika kuziganizira apa:

Tayika chikwatu chokhazikitsa /var/lib/etcd mu pod kuti deta ya etcd isungidwe pambuyo poyambitsanso (ngati izi sizinachitike, gulu lamagulu lidzachotsedwa nthawi iliyonse pod ikayambiranso, zomwe sizingakhale zabwino ngakhale kukhazikitsa Kubernetes kochepa).

Tayika hostNetwork: true. Kukhazikitsa uku, mosadabwitsa, kumakonza etcd kuti agwiritse ntchito netiweki yolandila m'malo mwa netiweki yamkati ya pod (izi zipangitsa kuti seva ya API ikhale yosavuta kupeza gulu la etcd).

Cheke chosavuta chikuwonetsa kuti etcd ikuyendadi pa localhost ndikusunga deta ku disk:

$ curl localhost:2379/version
{"etcdserver":"3.4.3","etcdcluster":"3.4.0"}
$ sudo tree /var/lib/etcd/
/var/lib/etcd/
└── member
    ├── snap
    │   └── db
    └── wal
        ├── 0.tmp
        └── 0000000000000000-0000000000000000.wal

Kuyambitsa seva ya API

Kuyendetsa seva ya Kubernetes API ndikosavuta. Parameter yokhayo yomwe ikufunika kudutsa ndi --etcd-servers, amachita zomwe mukuyembekezera:

apiVersion: v1
kind: Pod
metadata:
  name: kube-apiserver
  namespace: kube-system
spec:
  containers:
  - name: kube-apiserver
    command:
    - kube-apiserver
    - --etcd-servers=http://127.0.0.1:2379
    image: k8s.gcr.io/kube-apiserver:v1.18.5
  hostNetwork: true

Ikani fayilo ya YAML iyi m'ndandanda pods, ndipo seva ya API iyamba. Kufufuza ndi curl ikuwonetsa kuti Kubernetes API ikumvera pa doko 8080 ndi mwayi wotseguka - palibe kutsimikizika kofunikira!

$ curl localhost:8080/healthz
ok
$ curl localhost:8080/api/v1/pods
{
  "kind": "PodList",
  "apiVersion": "v1",
  "metadata": {
    "selfLink": "/api/v1/pods",
    "resourceVersion": "59"
  },
  "items": []
}

(Kachiwiri, musamayendetse izi popanga! Ndinadabwitsidwa pang'ono kuti zosintha zosasinthika ndizosatetezeka. Koma ndikuganiza kuti izi ndikupangitsa chitukuko ndi kuyesa kukhala kosavuta.)

Ndipo, modabwitsa, kubectl imagwira ntchito m'bokosi popanda zina zowonjezera!

$ ./kubectl version
Client Version: version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.5", GitCommit:"e6503f8d8f769ace2f338794c914a96fc335df0f", GitTreeState:"clean", BuildDate:"2020-06-26T03:47:41Z", GoVersion:"go1.13.9", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.5", GitCommit:"e6503f8d8f769ace2f338794c914a96fc335df0f", GitTreeState:"clean", BuildDate:"2020-06-26T03:39:24Z", GoVersion:"go1.13.9", Compiler:"gc", Platform:"linux/amd64"}
$ ./kubectl get pod
No resources found in default namespace.

vuto

Koma ngati mukumba mozama, chinachake chikuwoneka kuti sichikuyenda bwino:

$ ./kubectl get pod -n kube-system
No resources found in kube-system namespace.

Ma static pod omwe tidapanga apita! M'malo mwake, node yathu ya kubelet sinapezeke konse:

$ ./kubectl get nodes
No resources found in default namespace.

Vuto ndi chiyani? Ngati mukukumbukira ndime zingapo zapitazo, tidayambitsa kubelet ndi magawo osavuta kwambiri a mzere wamalamulo, kotero kubelet sadziwa kulumikizana ndi seva ya API ndikudziwitsa za momwe akukhalira. Titaphunzira zolembedwazo, timapeza mbendera yofananira:

--kubeconfig string

Njira yopita ku fayilo kubeconfig, yomwe imalongosola momwe mungalumikizire ku seva ya API. Kupezeka --kubeconfig imathandizira mawonekedwe a seva ya API, ayi --kubeconfig imathandizira mawonekedwe akunja.

Nthawi yonseyi, osadziwa, timayendetsa kubelet mu "offline mode." (Tikadakhala oyenda, titha kuganiza za kubelet yoyima ngati "Kubernetes yocheperako", koma zingakhale zotopetsa). Kuti kasinthidwe "zenizeni" agwire ntchito, tifunika kupatsira fayilo ya kubeconfig ku kubelet kuti idziwe kulankhula ndi seva ya API. Mwamwayi ndizosavuta (popeza tilibe kutsimikizika kapena zovuta za satifiketi):

apiVersion: v1
kind: Config
clusters:
- cluster:
    server: http://127.0.0.1:8080
  name: mink8s
contexts:
- context:
    cluster: mink8s
  name: mink8s
current-context: mink8s

Sungani izi ngati kubeconfig.yaml, kupha ndondomeko kubelet ndikuyambanso ndi magawo ofunikira:

$ sudo ./kubelet --pod-manifest-path=pods --kubeconfig=kubeconfig.yaml

(Mwa njira, ngati mutayesa kupeza API kudzera mu curl pamene kubelet sikuyenda, mudzapeza kuti ikugwirabe ntchito! Kubelet si "kholo" la ma pod ake ngati Docker, ali ngati "control daemon.” Mitsuko yoyendetsedwa ndi kubelet idzapitilirabe mpaka kubelet itayimitsa.)

Mumphindi zochepa kubectl Ayenera kutiwonetsa makoko ndi mfundo monga tikuyembekezera:

$ ./kubectl get pods -A
NAMESPACE     NAME                    READY   STATUS             RESTARTS   AGE
default       hello-mink8s            0/1     CrashLoopBackOff   261        21h
kube-system   etcd-mink8s             1/1     Running            0          21h
kube-system   kube-apiserver-mink8s   1/1     Running            0          21h
$ ./kubectl get nodes -owide
NAME     STATUS   ROLES    AGE   VERSION   INTERNAL-IP    EXTERNAL-IP   OS-IMAGE             KERNEL-VERSION       CONTAINER-RUNTIME
mink8s   Ready    <none>   21h   v1.18.5   10.70.10.228   <none>        Ubuntu 18.04.4 LTS   4.15.0-109-generic   docker://19.3.6

Tiyeni tidziyamike nthawi ino (ndikudziwa kuti ndadziyamikira kale) - tili ndi "gulu" lochepa la Kubernetes lomwe likuyenda ndi API yogwira ntchito mokwanira!

Timayamba pansi

Tsopano tiyeni tiwone zomwe API imatha. Tiyeni tiyambe ndi nginx pod:

apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  containers:
  - image: nginx
    name: nginx

Apa tikupeza cholakwika chochititsa chidwi:

$ ./kubectl apply -f nginx.yaml
Error from server (Forbidden): error when creating "nginx.yaml": pods "nginx" is
forbidden: error looking up service account default/default: serviceaccount
"default" not found
$ ./kubectl get serviceaccounts
No resources found in default namespace.

Apa tikuwona momwe chilengedwe chathu cha Kubernetes sichinakwaniritsire - tilibe akaunti zantchito. Tiyeni tiyesenso popanga pawokha akaunti yantchito ndikuwona zomwe zimachitika:

$ cat <<EOS | ./kubectl apply -f -
apiVersion: v1
kind: ServiceAccount
metadata:
  name: default
  namespace: default
EOS
serviceaccount/default created
$ ./kubectl apply -f nginx.yaml
Error from server (ServerTimeout): error when creating "nginx.yaml": No API
token found for service account "default", retry after the token is
automatically created and added to the service account

Ngakhale titapanga akaunti yautumiki pamanja, chizindikiro chotsimikizika sichimapangidwa. Pamene tikupitiliza kuyesa "gulu" lathu la minimalistic, tipeza kuti zinthu zambiri zothandiza zomwe zimachitika zokha sizikhala zikusoweka. Seva ya Kubernetes API ndi yocheperako kwambiri, ndikukweza kolemetsa komanso kusinthika kwadzidzidzi kumachitika mwa owongolera osiyanasiyana ndi ntchito zakumbuyo zomwe sizikuyendabe.

Titha kuthana ndi vutoli pokhazikitsa njira automountServiceAccountToken pa akaunti yautumiki (popeza sitidzayenera kuigwiritsa ntchito):

$ cat <<EOS | ./kubectl apply -f -
apiVersion: v1
kind: ServiceAccount
metadata:
  name: default
  namespace: default
automountServiceAccountToken: false
EOS
serviceaccount/default configured
$ ./kubectl apply -f nginx.yaml
pod/nginx created
$ ./kubectl get pods
NAME    READY   STATUS    RESTARTS   AGE
nginx   0/1     Pending   0          13m

Pomaliza, chithunzichi chawonekera! Koma kwenikweni siziyamba chifukwa tilibe wokonza (scheduler) ndi gawo lina lofunikira la Kubernetes. Apanso, tikuwona kuti Kubernetes API ndi "osayankhula" modabwitsa - mukapanga Pod mu API, imalembetsa, koma samayesa kudziwa kuti ndi node yanji yoyendetsa.

M'malo mwake, simusowa wokonza kuti ayendetse pod. Mutha kuwonjezera pamanja node ku chiwonetsero chazithunzi nodeName:

apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  containers:
  - image: nginx
    name: nginx
  nodeName: mink8s

(Sinthani mink8s ku dzina la node.) Mukachotsa ndikuyika, tikuwona kuti nginx yayamba ndipo ikumvetsera adilesi ya IP yamkati:

$ ./kubectl delete pod nginx
pod "nginx" deleted
$ ./kubectl apply -f nginx.yaml
pod/nginx created
$ ./kubectl get pods -owide
NAME    READY   STATUS    RESTARTS   AGE   IP           NODE     NOMINATED NODE   READINESS GATES
nginx   1/1     Running   0          30s   172.17.0.2   mink8s   <none>           <none>
$ curl -s 172.17.0.2 | head -4
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>

Kuti muwonetsetse kuti maukonde pakati pa ma pod akugwira ntchito moyenera, titha kuyendetsa ma curl kuchokera ku pod ina:

$ cat <<EOS | ./kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
  name: curl
spec:
  containers:
  - image: curlimages/curl
    name: curl
    command: ["curl", "172.17.0.2"]
  nodeName: mink8s
EOS
pod/curl created
$ ./kubectl logs curl | head -6
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>

Ndizosangalatsa kukumba m'malo awa ndikuwona zomwe zimagwira ntchito ndi zomwe sizikuyenda. Ndinapeza kuti ConfigMap ndi Chinsinsi zimagwira ntchito monga momwe zimayembekezeredwa, koma Service ndi Deployment sizitero.

Kupambana!

Cholembachi chikutalika, kotero ndilengeza chipambano ndikunena kuti uku ndikusintha koyenera komwe kumatha kutchedwa "Kubernetes".Kufotokozera mwachidule: ma binaries anayi, magawo asanu a mzere wamalamulo ndi "okha" mizere 45 ya YAML (osati kwambiri ndi Kubernetes) ndipo tili ndi zinthu zingapo zomwe zikugwira ntchito:

Ma Pods amayendetsedwa pogwiritsa ntchito Kubernetes API yokhazikika (yokhala ndi ma hacks ochepa)
Mutha kukweza ndi kukonza zithunzi zokhala ndi anthu ambiri
Ma Pod amakhalabe amoyo ndikuyambiranso
Kulumikizana pakati pa ma pod mkati mwa node yomweyo kumagwira ntchito bwino
ConfigMap, Chinsinsi ndi ntchito yosavuta yosungiramo momwe amayembekezera

Koma zambiri zomwe zimapangitsa Kubernetes kukhala zothandiza zikusowabe, monga:

Pod Scheduler
Kutsimikizira / chilolezo
Manode angapo
Network of services
Magulu amkati a DNS
Owongolera maakaunti a ntchito, kutumiza, kuphatikiza ndi opereka mtambo ndi zina zambiri zomwe Kubernetes amabweretsa

Ndiye tinapeza chiyani kwenikweni? Kubernetes API, ikuyenda yokha, ndi nsanja chabe chotengera chochita zokha. Sichichita zambiri - ndi ntchito kwa owongolera osiyanasiyana ndi ogwiritsa ntchito API - koma imapereka malo okhazikika opangira zokha.

Dziwani zambiri zamaphunzirowa mu webinar yaulere.

Werengani zambiri:

Source: www.habr.com

Minimum Viable Kubernetes