Kubernetes 101

128 Pages·2021·12.004 MB·English

by  Jeff Geerling and Katherine Geerling

Kubernetes 101
Learn the basics of Kubernetes and
container-based infrastructure.
Jeff Geerling and Katherine Geerling
Thisbookisforsaleathttp://leanpub.com/kubernetes-101
Thisversionwaspublishedon2021-07-29
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©2021JeffGeerlingandKatherineGeerling
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Also By Jeff Geerling
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Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i
Whoisthisbookfor? . . . . . . . . . . . . . . . . . . ii
Typographicconventions . . . . . . . . . . . . . . . . ii
Pleasehelpimprovethisbook! . . . . . . . . . . . . . iv
CurrentPublishedBookVersionInformation . iv
AbouttheAuthor. . . . . . . . . . . . . . . . . . . . . iv
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . v
ExamplesRepository . . . . . . . . . . . . . . . . . . . viii
Otherresources . . . . . . . . . . . . . . . . . . . . . . ix
Chapter1-Hello,Kubernetes! . . . . . . . . . . . . . . 1
KubernetesOrigins . . . . . . . . . . . . . . . . . . . . 1
IsKubernetesRightforYou? . . . . . . . . . . . . . . 3
KubernetesEnvironments . . . . . . . . . . . . . . . 5
InstructionsforMinikube . . . . . . . . . . . . . . . . 6
BuildingtheexampleDockerimage . . . . . . . . . 8
Chapter2-Containers . . . . . . . . . . . . . . . . . . . 10
WhydoesKubernetesusecontainers? . . . . . . . . 10
ContainerHistory:VendorWars . . . . . . . . . . . 11
Docker,containerd,andrunC . . . . . . . . . . 12
rktandCoreOS . . . . . . . . . . . . . . . . . . . 14
KubernetesContainerRuntime . . . . . . . . . 14
CONTENTS
CRI-O . . . . . . . . . . . . . . . . . . . . . . . . . 14
ModernContainerRuntimeoptions. . . . . . . 15
Howdoyoubuildacontainer?DockervsBuildah 15
Instructionsfor‘HelloGo’app . . . . . . . . . . . . . 16
Buildthe‘HelloGo’Dockercontainerimage . . . . 17
PushthecontainerimagetoaprivateDockerregistry 17
Chapter3-Deployingapps . . . . . . . . . . . . . . . . 19
CreatingaLinodeClusterforcloud-basedtesting . 19
DeployingHelloGointoKubernetes . . . . . . . . . 21
ExposingtheHelloGoApp. . . . . . . . . . . . . . . 24
ScalingtheHelloGoApp . . . . . . . . . . . . . . . . 26
UpdatingtheGoApp . . . . . . . . . . . . . . . . . . 28
RollingbacktheDeployment . . . . . . . . . . . . . 29
Chapter4-Real-worldapps . . . . . . . . . . . . . . . . 30
InstallingDrupalonaTraditionalLAMPserver . . 30
LAMPServerSetupfordrupal . . . . . . . . . . 31
AutomatingtheInstallation . . . . . . . . . . . . . . 34
Installing Drupal on Kubernetes using Bitnami’s
HelmChart . . . . . . . . . . . . . . . . . . . . 35
InstallHelm . . . . . . . . . . . . . . . . . . . . . 36
InstalltheDrupalChart . . . . . . . . . . . . . . 36
ExposingaLoadBalancerinMinikube . . . . . 37
ChangingChartOptions . . . . . . . . . . . . . 37
CleaningUp . . . . . . . . . . . . . . . . . . . . . 38
DrupalDirectlyinKubernetes-Let’sDoit[Mostly 38
DeployingtheDrupalKubernetesManifests . 39
Chapter5-ScalingDrupalink8s. . . . . . . . . . . . . 43
FixingthescalabilityissuewithDrupalPods . . . . 43
SharedStorageOptions . . . . . . . . . . . . . . 44
RookandCeph . . . . . . . . . . . . . . . . . . . 44
NFS . . . . . . . . . . . . . . . . . . . . . . . . . . 45
CONTENTS
SetupanNFSserver . . . . . . . . . . . . . . . . . . . 46
Reconfigure the Drupal PersistentVolumeClaim
forNFS . . . . . . . . . . . . . . . . . . . . . . 46
SetupNFSclientprovisionerinK8s . . . . . . 47
DeployDrupalandMySQL(MariaDB) . . . . . 48
SaveaFileandobserveit . . . . . . . . . . . . . 49
ScaleDrupalup…anddown! . . . . . . . . . . . . . . 49
UseHorizontalPodAutoscaling(HPA) . . . . . . . 51
Setupmetrics-server . . . . . . . . . . . . . . . 51
ConfiguringHPAforDrupal . . . . . . . . . . . 52
TestingHPAforDrupal . . . . . . . . . . . . . . 53
ScalingDatabases . . . . . . . . . . . . . . . . . . . . 54
Chapter6-DNS,TLS,Cron,Logging . . . . . . . . . . 56
SettingthingsupfromEpisode5 . . . . . . . . . . . 56
DNSandIngresssetupforDrupal . . . . . . . . . . . 57
SetupanNGINXIngressController . . . . . . 60
SetupIngressforDrupal . . . . . . . . . . . . . 61
ExternalDNSIntegration . . . . . . . . . . . . . 61
SetupTLSwithcert-managerandLet’sEncrypt. . 62
KeepingDrupalHappywithaCronJob . . . . . . . 65
MonitoringDrupal’sLogs. . . . . . . . . . . . . . . . 68
UsinganExternalSaaSLogAggregator . . . . 68
RunningyourownELKStack . . . . . . . . . . 69
RelyingonaServiceMesh . . . . . . . . . . . . 69
Usingyourcloudprovider’ssolution . . . . . . 70
Chapter7-Hello,Operator! . . . . . . . . . . . . . . . . 71
WhatareOperators? . . . . . . . . . . . . . . . . . . . 71
TheConcept . . . . . . . . . . . . . . . . . . . . . 72
TheExecution . . . . . . . . . . . . . . . . . . . . 73
WhynotuseanOperator? . . . . . . . . . . . . 75
PopularKubernetesOperators . . . . . . . . . . . . . 76
CONTENTS
BuildyourownOperator . . . . . . . . . . . . . . . . 76
BuildinganOperatorwithOperatorSDK . . . 78
Anylanguage,includingPythonorRust! . . . 83
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 83
Chapter8-Kube,MeetPi . . . . . . . . . . . . . . . . . 84
HeavyMetalKubernetes . . . . . . . . . . . . . . . . 84
StartwithTrainingWheels . . . . . . . . . . . . . . . 85
TheRaspberryPimakesforCompactClusters 86
TheRaspberryPisipsenergy,andkeepsitscool 88
The Raspberry Pi teaches lessons about scala-
bility . . . . . . . . . . . . . . . . . . . 89
ARMisnotallsunshineandroses . . . . . . . . 91
InstallingaKubernetesDistribution . . . . . . . . . 92
kubeadm . . . . . . . . . . . . . . . . . . . . . . . 93
SettinguptheRaspberryPiDramble . . . . . . . . . 94
GoingFurther . . . . . . . . . . . . . . . . . . . . . . . 95
OtherGuides . . . . . . . . . . . . . . . . . . . . 96
Chapter9-SecretsandConfiguration . . . . . . . . . 97
Chapter10-MonitoringKubernetes . . . . . . . . . . 98
TwoClusterstoMonitor. . . . . . . . . . . . . . 99
ClusterVisibilitywithLens. . . . . . . . . . . . . . . 99
InstallLens . . . . . . . . . . . . . . . . . . . . . . 100
InspectyourclusterswithLens . . . . . . . . . 100
ExplorePodLogs . . . . . . . . . . . . . . . . . . 101
LogintoNodesandPods . . . . . . . . . . . . . 101
Visitwebservicesinabrowser. . . . . . . . . . 103
Manageresources . . . . . . . . . . . . . . . . . . 103
PrometheusandGrafana . . . . . . . . . . . . . . . . 104
InstallPrometheusandGrafanausingHelm . 104
AccessGrafana . . . . . . . . . . . . . . . . . . . 105
GrafanaDashboards . . . . . . . . . . . . . . . . 108
CONTENTS
MaintainingGrafana . . . . . . . . . . . . . . . . 108
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 108
Afterword . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Preface
In 2020, the entire global community experienced a shock in
theformoftheCOVID-19pandemic.
Entire industries had to pivot overnight or risk ruin. Tech,
fortunately for those of us in the industry, was suddenly in
highdemand.
Since I had a good deal of working knowledge about Ku-
bernetes, and since I also finished a popular video series on
Ansible earlier in the year, I decided to live-stream a series
‘Kubernetes 101’ to try to train people new to cloud-native
infrastructureonthispopularclusteringsoftware.
After many thousands of developers have viewed the video
series, I decided to translate the content of the video series
into this introductory-level book, so even more people could
diveintoKubernetesandlearnanewskill.
Whether you’re new to infrastructure, or you’re a veteran,
Kubernetes can be complex and daunting. This book follows
the progress of the video series, and starts with the basics,
teaching each new concept with concrete, real-world exam-
ples.
IhopeyouenjoythebookasmuchasIenjoyedwritingit!
—JeffGeerling,2021