Zosangalatsa za 6 pakugwira ntchito kwa Kubernetes [ndi yankho lawo]

Kwa zaka zambiri zomwe timagwiritsa ntchito Kubernetes popanga, tapeza nkhani zambiri zosangalatsa za momwe nsikidzi m'magawo osiyanasiyana amachitidwe zimabweretsera zotsatira zosasangalatsa komanso / kapena zosamvetsetseka zomwe zimakhudza magwiridwe antchito a zotengera ndi ma pod. M'nkhaniyi tasankha zina mwazofala kapena zosangalatsa. Ngakhale mutakhala kuti mulibe mwayi wokumana ndi zoterezi, kuwerenga nkhani zazifupi ngati za ofufuza - makamaka "woyamba" - kumakhala kosangalatsa nthawi zonse, sichoncho?

Nkhani 1. Supercronic ndi Docker ikulendewera

Pa gulu limodzi, tinkalandira nthawi ndi nthawi Docker yozizira, yomwe imasokoneza magwiridwe antchito amgululi. Nthawi yomweyo, zotsatirazi zidawonedwa muzolemba za Docker:

level=error msg="containerd: start init process" error="exit status 2: "runtime/cgo: pthread_create failed: No space left on device
SIGABRT: abort
PC=0x7f31b811a428 m=0

goroutine 0 [idle]:

goroutine 1 [running]:
runtime.systemstack_switch() /usr/local/go/src/runtime/asm_amd64.s:252 fp=0xc420026768 sp=0xc420026760
runtime.main() /usr/local/go/src/runtime/proc.go:127 +0x6c fp=0xc4200267c0 sp=0xc420026768
runtime.goexit() /usr/local/go/src/runtime/asm_amd64.s:2086 +0x1 fp=0xc4200267c8 sp=0xc4200267c0

goroutine 17 [syscall, locked to thread]:
runtime.goexit() /usr/local/go/src/runtime/asm_amd64.s:2086 +0x1

…

Chomwe chimatisangalatsa kwambiri pa cholakwikachi ndi uthengawu: pthread_create failed: No space left on device. Kuphunzira Mwachangu zolemba adafotokoza kuti Docker sakanatha kuyimitsa njira, ndichifukwa chake amaundana nthawi ndi nthawi.

Pakuwunika, chithunzi chotsatirachi chikugwirizana ndi zomwe zikuchitika:

Zofananazi zimawonedwanso m'malo ena:

M'magawo omwewo tikuwona:

root@kube-node-1 ~ # ps auxfww | grep curl -c
19782
root@kube-node-1 ~ # ps auxfww | grep curl | head
root     16688  0.0  0.0      0     0 ?        Z    Feb06   0:00      |       _ [curl] <defunct>
root     17398  0.0  0.0      0     0 ?        Z    Feb06   0:00      |       _ [curl] <defunct>
root     16852  0.0  0.0      0     0 ?        Z    Feb06   0:00      |       _ [curl] <defunct>
root      9473  0.0  0.0      0     0 ?        Z    Feb06   0:00      |       _ [curl] <defunct>
root      4664  0.0  0.0      0     0 ?        Z    Feb06   0:00      |       _ [curl] <defunct>
root     30571  0.0  0.0      0     0 ?        Z    Feb06   0:00      |       _ [curl] <defunct>
root     24113  0.0  0.0      0     0 ?        Z    Feb06   0:00      |       _ [curl] <defunct>
root     16475  0.0  0.0      0     0 ?        Z    Feb06   0:00      |       _ [curl] <defunct>
root      7176  0.0  0.0      0     0 ?        Z    Feb06   0:00      |       _ [curl] <defunct>
root      1090  0.0  0.0      0     0 ?        Z    Feb06   0:00      |       _ [curl] <defunct>

Zinadziwika kuti khalidweli ndi zotsatira za pod ntchito ndi wapamwamba kwambiri (chida cha Go chomwe timagwiritsa ntchito poyendetsa ntchito za cron mu pod):

 _ docker-containerd-shim 833b60bb9ff4c669bb413b898a5fd142a57a21695e5dc42684235df907825567 /var/run/docker/libcontainerd/833b60bb9ff4c669bb413b898a5fd142a57a21695e5dc42684235df907825567 docker-runc
|   _ /usr/local/bin/supercronic -json /crontabs/cron
|       _ /usr/bin/newrelic-daemon --agent --pidfile /var/run/newrelic-daemon.pid --logfile /dev/stderr --port /run/newrelic.sock --tls --define utilization.detect_aws=true --define utilization.detect_azure=true --define utilization.detect_gcp=true --define utilization.detect_pcf=true --define utilization.detect_docker=true
|       |   _ /usr/bin/newrelic-daemon --agent --pidfile /var/run/newrelic-daemon.pid --logfile /dev/stderr --port /run/newrelic.sock --tls --define utilization.detect_aws=true --define utilization.detect_azure=true --define utilization.detect_gcp=true --define utilization.detect_pcf=true --define utilization.detect_docker=true -no-pidfile
|       _ [newrelic-daemon] <defunct>
|       _ [curl] <defunct>
|       _ [curl] <defunct>
|       _ [curl] <defunct>
…

Vuto ndi ili: pamene ntchito ikuyendetsedwa mu supercronic, ndondomekoyi imayambitsidwa ndi izo sangathe kutha bwino, kusanduka zombie.

ndemanga: Kunena zowona, njira zimayambitsidwa ndi ntchito za cron, koma supercronic si init system ndipo sangathe "kutengera" njira zomwe ana ake anabala. Zizindikiro za SIGHUP kapena SIGTERM zikakwezedwa, sizimaperekedwa kwa mwana, zomwe zimapangitsa kuti mwana asathere komanso kukhalabe mu zombie. Mutha kuwerenga zambiri za izi, mwachitsanzo, mu nkhani yotere.

Pali njira ziwiri zothetsera mavuto:

1. Monga ntchito kwakanthawi - onjezani kuchuluka kwa ma PID mudongosolo panthawi imodzi:

          /proc/sys/kernel/pid_max (since Linux 2.5.34)
                 This file specifies the value at which PIDs wrap around (i.e., the value in this file is one greater than the maximum PID).  PIDs greater than this  value  are  not  allo‐
                 cated;  thus, the value in this file also acts as a system-wide limit on the total number of processes and threads.  The default value for this file, 32768, results in the
                 same range of PIDs as on earlier kernels

2. Kapena yambitsani ntchito mu supercronic osati mwachindunji, koma pogwiritsa ntchito zomwezo ife, yomwe imatha kuletsa njira molondola osati kutulutsa Zombies.

Nkhani 2. "Zombies" pochotsa gulu

Kubelet adayamba kudya CPU yambiri:

Palibe amene angakonde izi, kotero tinadzipangira zida wangwiro ndipo anayamba kulimbana ndi vutoli. Zotsatira za kafukufukuyu zinali motere:

• Kubelet amathera nthawi yopitilira gawo limodzi mwa magawo atatu a nthawi yake ya CPU kukokera kukumbukira m'magulu onse:

  

• Pamndandanda wamakalata opanga ma kernel omwe mungapeze kukambirana za vuto. Mwachidule, mfundo ikufika pa izi: mafayilo osiyanasiyana a tmpfs ndi zinthu zina zofananira sizimachotsedwa kwathunthu padongosolo pochotsa gulu, lotchedwa memcg Zombie. Posakhalitsa adzachotsedwa pa cache ya tsamba, koma pali zokumbukira zambiri pa seva ndipo kernel siwona mfundo yowononga nthawi powachotsa. Ndicho chifukwa chake amangowonjezera. N’chifukwa chiyani zimenezi zikuchitikadi? Iyi ndi seva yokhala ndi ntchito za cron zomwe nthawi zonse zimapanga ntchito zatsopano, komanso ndi ma pod atsopano. Chifukwa chake, magulu atsopano amapangidwira zotengera momwemo, zomwe zimachotsedwa posachedwa.
• Chifukwa chiyani cAdvisor mu kubelet amawononga nthawi yochuluka chonchi? Izi ndizosavuta kuwona ndi kuphedwa kosavuta time cat /sys/fs/cgroup/memory/memory.stat. Ngati pamakina athanzi ntchitoyo imatenga masekondi 0,01, ndiye kuti pazovuta cron02 zimatenga masekondi 1,2. Chinthucho ndi chakuti cAdvisor, yomwe imawerenga deta kuchokera ku sysfs pang'onopang'ono, imayesetsa kuganizira kukumbukira komwe kumagwiritsidwa ntchito mumagulu a zombie.
• Kuti tichotse Zombies mwamphamvu, tidayesa kuchotsa ma cache monga tikulimbikitsidwa mu LKML: sync; echo 3 > /proc/sys/vm/drop_caches, - koma kernel inakhala yovuta kwambiri ndipo inagunda galimotoyo.

Zoyenera kuchita? Vuto likukonzedwa (perekani, ndi kufotokozera onani kumasula uthenga) zosintha za kernel Linux mpaka 4.16.

Mbiri 3. Systemd ndi phiri lake

Apanso, kubelet ikugwiritsa ntchito zinthu zambiri pamalo ena, koma nthawi ino ikuwononga kukumbukira kwambiri:

Zinapezeka kuti panali vuto ndi systemd yomwe imagwiritsidwa ntchito mu Ubuntu 16.04, ndipo zimachitika poyang'anira zomangira zomwe zimapangidwa kuti zilumikizane subPath kuchokera ku ConfigMaps kapena zinsinsi. Pambuyo pomaliza kumaliza ntchito yake ntchito ya systemd ndi kukwera kwake kwa ntchito kumakhalabe mu dongosolo. M'kupita kwa nthawi, ambiri a iwo amadziunjikira. Pali ngakhale zovuta pamutuwu:

1. #5916;
2. kubernetes #57345.

...chomaliza chomwe chimanena za PR mu systemd: #7811 (nkhani mu systemd - #7798).

Vuto sililiponso Ubuntu 18.04, koma ngati mukufuna kupitiriza kugwiritsa ntchito Ubuntu 16.04, njira yathu yothetsera vutoli ingakuthandizeni.

Chifukwa chake tidapanga DaemonSet zotsatirazi:

---
apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
  labels:
    app: systemd-slices-cleaner
  name: systemd-slices-cleaner
  namespace: kube-system
spec:
  updateStrategy:
    type: RollingUpdate
  selector:
    matchLabels:
      app: systemd-slices-cleaner
  template:
    metadata:
      labels:
        app: systemd-slices-cleaner
    spec:
      containers:
      - command:
        - /usr/local/bin/supercronic
        - -json
        - /app/crontab
        Image: private-registry.org/systemd-slices-cleaner/systemd-slices-cleaner:v0.1.0
        imagePullPolicy: Always
        name: systemd-slices-cleaner
        resources: {}
        securityContext:
          privileged: true
        volumeMounts:
        - name: systemd
          mountPath: /run/systemd/private
        - name: docker
          mountPath: /run/docker.sock
        - name: systemd-etc
          mountPath: /etc/systemd
        - name: systemd-run
          mountPath: /run/systemd/system/
        - name: lsb-release
          mountPath: /etc/lsb-release-host
      imagePullSecrets:
      - name: antiopa-registry
      priorityClassName: cluster-low
      tolerations:
      - operator: Exists
      volumes:
      - name: systemd
        hostPath:
          path: /run/systemd/private
      - name: docker
        hostPath:
          path: /run/docker.sock
      - name: systemd-etc
        hostPath:
          path: /etc/systemd
      - name: systemd-run
        hostPath:
          path: /run/systemd/system/
      - name: lsb-release
        hostPath:
          path: /etc/lsb-release

... ndipo imagwiritsa ntchito script zotsatirazi:

#!/bin/bash

# we will work only on xenial
hostrelease="/etc/lsb-release-host"
test -f ${hostrelease} && grep xenial ${hostrelease} > /dev/null || exit 0

# sleeping max 30 minutes to dispense load on kube-nodes
sleep $((RANDOM % 1800))

stoppedCount=0
# counting actual subpath units in systemd
countBefore=$(systemctl list-units | grep subpath | grep "run-" | wc -l)
# let's go check each unit
for unit in $(systemctl list-units | grep subpath | grep "run-" | awk '{print $1}'); do
  # finding description file for unit (to find out docker container, who born this unit)
  DropFile=$(systemctl status ${unit} | grep Drop | awk -F': ' '{print $2}')
  # reading uuid for docker container from description file
  DockerContainerId=$(cat ${DropFile}/50-Description.conf | awk '{print $5}' | cut -d/ -f6)
  # checking container status (running or not)
  checkFlag=$(docker ps | grep -c ${DockerContainerId})
  # if container not running, we will stop unit
  if [[ ${checkFlag} -eq 0 ]]; then
    echo "Stopping unit ${unit}"
    # stoping unit in action
    systemctl stop $unit
    # just counter for logs
    ((stoppedCount++))
    # logging current progress
    echo "Stopped ${stoppedCount} systemd units out of ${countBefore}"
  fi
done

... ndipo imayenda mphindi 5 zilizonse pogwiritsa ntchito supercronic yomwe yatchulidwa kale. Dockerfile yake ikuwoneka motere:

FROM ubuntu:16.04
COPY rootfs /
WORKDIR /app
RUN apt-get update && 
    apt-get upgrade -y && 
    apt-get install -y gnupg curl apt-transport-https software-properties-common wget
RUN add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu xenial stable" && 
    curl -fsSL https://download.docker.com/linux/ubuntu/gpg | apt-key add - && 
    apt-get update && 
    apt-get install -y docker-ce=17.03.0*
RUN wget https://github.com/aptible/supercronic/releases/download/v0.1.6/supercronic-linux-amd64 -O 
    /usr/local/bin/supercronic && chmod +x /usr/local/bin/supercronic
ENTRYPOINT ["/bin/bash", "-c", "/usr/local/bin/supercronic -json /app/crontab"]

Nkhani 4. Kupikisana pokonza ma pod

Zinazindikirika kuti: ngati tili ndi poto yoyikidwa pa mfundo ndipo chithunzi chake chikapopedwa kwa nthawi yayitali, ndiye kuti pod ina yomwe "inagunda" mfundo yomweyo imangokhalira kugwedezeka. sichiyamba kukoka chithunzi cha pod yatsopano. M'malo mwake, imadikirira mpaka chithunzi cha pod yapitayi chikokedwe. Zotsatira zake, poto yomwe idakonzedwa kale ndipo chithunzi chake chikadatsitsidwa mphindi imodzi yokha chikhala ngati containerCreating.

Zochitika zidzawoneka motere:

Normal  Pulling    8m    kubelet, ip-10-241-44-128.ap-northeast-1.compute.internal  pulling image "registry.example.com/infra/openvpn/openvpn:master"

Izo zikutanthauza kuti chithunzi chimodzi kuchokera ku registry pang'onopang'ono chingalepheretse kutumizidwa pa node.

Tsoka ilo, palibe njira zambiri zochotsera vutoli:

1. Yesani kugwiritsa ntchito Docker Registry yanu mwachindunji pagulu kapena mwachindunji ndi tsango (mwachitsanzo, GitLab Registry, Nexus, etc.);
2. Gwiritsani ntchito zinthu monga kuti asokonezeke.

Nkhani 5. Manode amalendewera chifukwa chosowa kukumbukira

Pakugwiritsa ntchito mapulogalamu osiyanasiyana, tidakumananso ndi vuto lomwe node imasiya kupezeka: SSH sichimayankha, ma daemoni onse owunikira amagwa, ndiyeno palibe (kapena pafupifupi chilichonse) chodabwitsa m'zipika.

Ndikuuzani pazithunzi pogwiritsa ntchito chitsanzo cha node imodzi yomwe MongoDB inkagwira ntchito.

Izi ndi zomwe atop amawoneka mpaka ngozi:

Ndipo monga chonchi - после ngozi:

Pakuwunika, palinso kulumpha kwakuthwa, komwe node imasiya kupezeka:

Chifukwa chake, kuchokera pazithunzi zikuwonekeratu kuti:

1. RAM pamakina ili pafupi ndi mapeto;
2. Pali kulumpha kwakukulu pakugwiritsa ntchito RAM, pambuyo pake kupeza makina onse kumayimitsidwa mwadzidzidzi;
3. Ntchito yayikulu ifika pa Mongo, yomwe imapangitsa kuti DBMS igwiritse ntchito kukumbukira komanso kuwerenga mwachangu kuchokera pa disk.

Zikuoneka kuti ngati mu Linux kukumbukira kwaulere kumatha (kupanikizika kwa kukumbukira kumachitika) ndipo palibe kusinthana, ndiye mpaka Wakupha wa OOM akafika, kusinthana kungachitike pakati pa kuponya masamba mu cache yatsamba ndikuwalemberanso ku diski. Izi zimachitika ndi kswapd, yomwe imamasula molimba mtima masamba ambiri okumbukira momwe angathere kuti agawidwe.

Tsoka ilo, ndi katundu wamkulu wa I / O wophatikizidwa ndi kukumbukira pang'ono kwaulere, kswapd imakhala nkhokwe ya dongosolo lonse, chifukwa amangika nacho onse magawo (zolakwika zamasamba) zamasamba amakumbukiro mudongosolo. Izi zitha kuchitika kwa nthawi yayitali ngati njira sizikufunanso kugwiritsa ntchito kukumbukira, koma zimakhazikika m'mphepete mwaphompho la OOM-wakupha.

Funso lachilengedwe ndilakuti: chifukwa chiyani wakupha wa OOM amabwera mochedwa kwambiri? Pakubwereza kwake kwaposachedwa, wakupha wa OOM ndi wopusa kwambiri: adzapha njirayi pokhapokha ngati kuyesa kugawa tsamba la kukumbukira kukulephera, i.e. ngati vuto la tsamba likulephera. Izi sizichitika kwa nthawi yayitali, chifukwa kswapd molimba mtima imamasula masamba okumbukira, kutaya posungira tsamba (dimba lonse I/O mu dongosolo, kwenikweni) kubwerera litayamba. Mwatsatanetsatane, ndi kufotokoza njira zofunika kuthetsa mavuto amenewa mu kernel, mukhoza kuwerenga apa.

Khalidwe ili ayenera kusintha ndi pakati Linux 4.6/XNUMX/XNUMX+.

Nkhani 6. Ma Pods akhazikika mu Pending state

M'magulu ena, momwe muli ma pod ambiri omwe akugwira ntchito, tinayamba kuzindikira kuti ambiri a iwo "amapachika" kwa nthawi yayitali m'boma. Pending, ngakhale zotengera za Docker zokha zikuyenda kale pama node ndipo zitha kugwiritsidwa ntchito pamanja.

Pa nthawi yomweyo, in describe palibe cholakwika:

  Type    Reason                  Age                From                     Message
  ----    ------                  ----               ----                     -------
  Normal  Scheduled               1m                 default-scheduler        Successfully assigned sphinx-0 to ss-dev-kub07
  Normal  SuccessfulAttachVolume  1m                 attachdetach-controller  AttachVolume.Attach succeeded for volume "pvc-6aaad34f-ad10-11e8-a44c-52540035a73b"
  Normal  SuccessfulMountVolume   1m                 kubelet, ss-dev-kub07    MountVolume.SetUp succeeded for volume "sphinx-config"
  Normal  SuccessfulMountVolume   1m                 kubelet, ss-dev-kub07    MountVolume.SetUp succeeded for volume "default-token-fzcsf"
  Normal  SuccessfulMountVolume   49s (x2 over 51s)  kubelet, ss-dev-kub07    MountVolume.SetUp succeeded for volume "pvc-6aaad34f-ad10-11e8-a44c-52540035a73b"
  Normal  Pulled                  43s                kubelet, ss-dev-kub07    Container image "registry.example.com/infra/sphinx-exporter/sphinx-indexer:v1" already present on machine
  Normal  Created                 43s                kubelet, ss-dev-kub07    Created container
  Normal  Started                 43s                kubelet, ss-dev-kub07    Started container
  Normal  Pulled                  43s                kubelet, ss-dev-kub07    Container image "registry.example.com/infra/sphinx/sphinx:v1" already present on machine
  Normal  Created                 42s                kubelet, ss-dev-kub07    Created container
  Normal  Started                 42s                kubelet, ss-dev-kub07    Started container

Pambuyo pokumba pang'ono, tidaganiza kuti kubelet alibe nthawi yotumiza zidziwitso zonse za ma pod ndi kuyesa kwa moyo / kukonzekera ku seva ya API.

Ndipo titaphunzira thandizo, tidapeza magawo otsatirawa:

--kube-api-qps - QPS to use while talking with kubernetes apiserver (default 5)
--kube-api-burst  - Burst to use while talking with kubernetes apiserver (default 10) 
--event-qps - If > 0, limit event creations per second to this value. If 0, unlimited. (default 5)
--event-burst - Maximum size of a bursty event records, temporarily allows event records to burst to this number, while still not exceeding event-qps. Only used if --event-qps > 0 (default 10) 
--registry-qps - If > 0, limit registry pull QPS to this value.
--registry-burst - Maximum size of bursty pulls, temporarily allows pulls to burst to this number, while still not exceeding registry-qps. Only used if --registry-qps > 0 (default 10)

Monga zikuwoneka, zokhazikika ndizochepa kwambiri, ndipo mu 90% amakwaniritsa zosowa zonse ... Komabe, kwa ife izi sizinali zokwanira. Choncho, timayika mfundo zotsatirazi:

--event-qps=30 --event-burst=40 --kube-api-burst=40 --kube-api-qps=30 --registry-qps=30 --registry-burst=40

... ndikuyambitsanso ma kubelets, pambuyo pake tidawona chithunzi chotsatira pama graph a mafoni ku seva ya API:

... ndipo inde, zonse zinayamba kuwuluka!

PS

Chifukwa chothandizira kusonkhanitsa nsikidzi ndikukonzekera nkhaniyi, ndikuthokoza kwambiri akatswiri ambiri a kampani yathu, makamaka kwa mnzanga wa gulu lathu la R&D Andrey Klimentyev (zuzu).

Pps

Werenganinso pa blog yathu:

• «kubectl-debug plugin yochotsa zolakwika mu Kubernetes pods".
• Malangizo ndi zidule za Kubernetes:
  • «Kusamutsa zinthu zomwe zikuyenda mu gulu ku kasamalidwe ka Helm 2";
  • «Za kugawa ma node ndi katundu pa intaneti";
  • «Kufikira kumasamba a dev";
  • «Kufulumizitsa bootstrap kwa database yayikulu".

Source: www.habr.com