θϩ͔Β࢝ΊΔ Kubernetes Controller 2019/09/27 Kubernetes Meetup #23 Operator Deep Dive

ࠓ೔ͷ໨ඪɾ࿩͢͜ͱ ɾKubernetesͷResourceΛ͋Δఔ౓஌͍ͬͯΔਓ͕ɺɹ ɹControllerͷ஌ࣝθϩͷঢ়ଶ͔ΒͰ΋Deep DiveʹΑͬͯɺ ɹControllerͷ࢓૊Έɾ಺෦࣮૷ʹ͍ͭͯཧղͰ͖Δ͜ͱ ɾKubernetes Controllerͷ֓ཁɾࢥ૝ ɾKubernetes Controllerͷ࢓૊Έ, ಺෦࣮૷ ɾControllerΛࢧ͑Δίϯϙʔωϯτ = ControllerͷϋΠϨϕϧʙϩʔϨϕϧ·Ͱ ࿩͢͜ͱ ໨ඪ

࿩͞ͳ͍͜ͱ ɾKubernetes Custom Controller + CRDͷৄࡉ ※ ͨͩ͠ɺ७ਖ਼Controllerͷ࢓૊ΈΛ஌Δ͜ͱ͸ɺ Custom ControllerΛ࣮૷͢Δ্Ͱ΋໾ཱͪ·͢ ɾKubernetes Custom ControllerΛ࣮૷͢ΔͨΊͷϑϨʔϜϫʔΫ KubebuilderɺOperator SDKͷৄࡉʹ͍ͭͯ͸࿩͠·ͤΜ ಺෦SDKͰ͋Δcontroller-runtime΍controller-toolsʹ͍ͭͯ΋ ຊൃදͰ͸৮Ε·ͤΜ ࿩͞ͳ͍͜ͱ controller-runtimeࢀߟ: https://www.slideshare.net/pfi/kubernete-meetup-tokyo-18-kubebuildercontrollerruntime

ΞδΣϯμ ɾ Kubernetes Controllerͱ͸ʁ ɾ Control Loop(Reconciliation Loop) ɾControllerΛࢧ͑Δɺ஌͓ͬͯ͘΂͖ίϯϙʔωϯτ ɾClient-Go - Informer - WorkQueue ɾControllerͷCycle, Main Logic ɾControllerͷ·ͱΊ - Reference

Kubernetes Controllerͱ͸ʁ ʙ ϋΠϨϕϧΞʔΩςΫνϟ ʙ

.BTUFS 8PSLFS 8PSLFS 8PSLFS KubernetesΞʔΩςΫνϟ͓͞Β͍ Master Node Worker Node

KubernetesϋΠϨϕϧΞʔΩςΫνϟ .BTUFS 8PSLFS FUDE DMPVEDPOUSPMMFS NBOBHFS /PEF $POUBJOFS 3VOUJNF LVCFMFU LVCF QSPYZ DPOUSPMMFS NBOBHFS BQJTFSWFS TDIFEVMFS /PEF $POUBJOFS 3VOUJNF LVCFMFU /PEF $POUBJOFS 3VOUJNF LVCFMFU DMPVE LVCF QSPYZ LVCF QSPYZ

KubernetesͷΞʔΩςΫνϟ ɾKubernetes͸෼ࢄΞʔΩςΫνϟɾ෼ࢄίϯϙʔωϯτ Master: ೝূɾೝՄ΍Resource ͷ؅ཧɺ ίϯςφͷεέδϡʔϦϯάͳͲͷશମ؅ཧ Worker: ίϯςφͷ࣮ߦ෦෼

KubernetesϋΠϨϕϧΞʔΩςΫνϟ .BTUFS 8PSLFS FUDE DMPVEDPOUSPMMFS NBOBHFS /PEF $POUBJOFS 3VOUJNF LVCFMFU LVCF QSPYZ DPOUSPMMFS NBOBHFS BQJTFSWFS TDIFEVMFS /PEF $POUBJOFS 3VOUJNF LVCFMFU /PEF $POUBJOFS 3VOUJNF LVCFMFU DMPVE LVCF QSPYZ LVCF QSPYZ

api-server / controller-manager api-server: Deployment΍ServiceͳͲͷObjectͷ࡞੒ɾߋ৽ɾ࡟আ (CRUD)ͷϦΫΤετΛड͚औΓɺૢ࡞Λߦ͏ Objectͷ৘ใΛσʔλετΞͰ͋Δetcdʹ֨ೲ͢Δ ※etcdʹΞΫηε͢Δίϯϙʔωϯτ͸api-serverͷΈ controller-manager: Controller͸ɺDeployment΍ServiceͳͲͷObjectͷ ؅ཧΛߦ͏ɻ controller-manager͸ɺController܈ͷ͔ͨ·Γ

controller-manager controller-manager: Ұͭͷϓϩηεʹෳ਺ͷController %FQMPZNFOU 3FQMJDB4FU %BFNPO4FU 4FSWJDF +PC $SPO+PC &OEQPJOU 4UBUFGVM4FU ʜ

3FQMJDB4FU $POUSPMMFS LJOE3FQMJDB4FU NFUBEBUB OBNFYYYYYY TQFD ʜ 3FTPVSDF 3FTPVSDF 3FTPVSDF ʜ 3FTPVSDF / ؅ཧ $POUSPM-PPQ .BOJGFTU ControllerͱResource Controller͕Resourceͷ؅ཧΛߦ͏ 3FQMJDB4FU$POUSPMMFSͷྫ

3FQMJDB4FU $POUSPMMFS ControllerͱResource Controller͸ɺͻͱͭͷResourceΛ؅ཧ͢Δ 3FQMJDB4FU 1PE %FQMPZNFOU $POUSPMMFS %FQMPZNFOU NBOBHF DSFBUF NBOBHF DSFBUF ࢀߟ: OwnerReference https://kubernetes.io/docs/concepts/workloads/controllers/garbage-collection/ ্ҐResource͕ԼҐResourceΛ؅ཧ͢Δ࢓૊Έͱͯ͠ʮOwnerReferenceʯ͕͋Δ ্ҐResourceΛ࡟আ͢ΔͱɺԼҐResource͸ΨϕʔδίϨΫγϣϯͰ࡟আ͞ΕΔ

Control Loop (Reconciliation Loop)

"DUVBM4UBUF $POUSPM-PPQ %FTJSFE4UBUF 3FBESFBMSFTPVSDFT $IBOHFJOUFSOBMFYUFSOBMSFTPVSDFT PCTFSWF BOBMZ[F "DU Controllerͷجຊݪཧ جຊݪཧ: Control Loop(Reconciliation Loop)

Control Loop(Reconciliation Loop) Controller Loop͸ɺControllerͷجຊݪཧ ※Reconciliation Loopͱ΋ݺ͹Ε͍ͯΔ Controller LoopͷྲྀΕ: 1. Resourceͷݱࡏͷঢ়ଶΛಡΈࠐΉ 2. ResourceΛ๬Μͩঢ়ଶʹมߋ͢Δ 3. Resourceͷঢ়ଶ(Status)Λߋ৽͢Δ Controller LoopʹΑͬͯɺ๬Μͩঢ়ଶΛએݴ͢Δ͜ͱͰ ؀ڥ͕ߏங͞ΕΔɻ = Immutable Infrastructure͕࣮ݱͰ͖Δ ϧʔϓ

3FQMJDBT ReplicaSetͷControl Loopྫ 3FQMJDBT 3FQMJDB4FU $POUSPMMFS 3FQMJDB4FU $POUSPMMFS 0CTFSWF ๬Μͩঢ়ଶ ݱࡏͷঢ়ଶ "DU

ReplicaSetΛApply ʙ σϦόϦ͞ΕΔ·Ͱ LJOE3FQMJDB4FU NFUBEBUB OBNFYYYYYY TQFD ʜ .BOJGFTU 6TFS .BTUFS 8PSLFS FUDE /PEF $POUBJOFS 3VOUJNF LVCFMFU LVCF QSPYZ BQJTFSWFS TDIFEVMFS ,VCFDUMBQQMZGNBOJGFTUZBNM †3FTPVSDFΛ"QQMZ͢Δ 3FQMJDB4FU $POUSPMMFS ᶃ3FQMJDB4FU͕ੜ੒͞ΕΔ

ReplicaSetΛApply ʙ σϦόϦ͞ΕΔ·Ͱ .BTUFS 8PSLFS FUDE /PEF $POUBJOFS 3VOUJNF LVCFMFU LVCF QSPYZ BQJTFSWFS TDIFEVMFS 3FQMJDB4FU $POUSPMMFS $POUSPM-PPQ ᶄ3FQMJDB4FU͕ੜ੒͞Εͨ͜ͱΛɺ3FQMJDB4FU$POUSPMMFS͕ݕ஌ ᶄ`ϝΠϯϩδοΫʹΑͬͯɺ TQFDOPEF/BNF͕ۭͷ1PEΛ࡞੒͢Δ DSFBUF ˞8PSLFSʹ͸·ͩσϦόϦ͞Εͳ͍

ReplicaSetΛApply ʙ σϦόϦ͞ΕΔ·Ͱ .BTUFS 8PSLFS FUDE /PEF $POUBJOFS 3VOUJNF LVCFMFU LVCF QSPYZ BQJTFSWFS TDIFEVMFS 3FQMJDB4FU $POUSPMMFS ᶅ4DIFEVMFS͕1PEͷ࡞੒Λݕ஌ queue ᶅ`1PEͷTQFDOPEF/BNF͕ۭͳͷͰɺ TDIEVMFS͕RVFVFʹ௥Ճ͢Δ

ReplicaSetΛApply ʙ σϦόϦ͞ΕΔ·Ͱ .BTUFS 8PSLFS FUDE /PEF $POUBJOFS 3VOUJNF LVCFMFU LVCF QSPYZ BQJTFSWFS TDIFEVMFS 3FQMJDB4FU $POUSPMMFS ᶆLVCFMFU͕1PEͷ࡞੒Λݕ஌ queue ᶆ`1PEͷTQFDOPEF/BNF͕ۭͳͷͰɺ LVCFMFU͸ॲཧΛεΩοϓ skip

ReplicaSetΛApply ʙ σϦόϦ͞ΕΔ·Ͱ .BTUFS 8PSLFS FUDE /PEF $POUBJOFS 3VOUJNF LVCFMFU LVCF QSPYZ BQJTFSWFS TDIFEVMFS 3FQMJDB4FU $POUSPMMFS ᶇ4DIFEVMFS͕1PEΛRVFVF͔ΒऔΓग़͢ queue ᶇ`ΞαΠϯՄೳͳ/PEFʹ1PEΛ εέδϡʔϦϯά͢Δ schedule ᶇ`1PEͷTQFDOPEF/BNFΛߋ৽ 6QEBUF TQFDOPEF/BNF

ReplicaSetΛApply ʙ σϦόϦ͞ΕΔ·Ͱ .BTUFS 8PSLFS FUDE /PEF $POUBJOFS 3VOUJNF LVCFMFU LVCF QSPYZ BQJTFSWFS TDIFEVMFS 3FQMJDB4FU $POUSPMMFS queue ᶈLVCFMFU͕1PEͷߋ৽Λݕ஌ ᶈ`LVCFMFU͕ίϯςφΛىಈ

ReplicaSetΛApply ʙ σϦόϦ͞ΕΔ·Ͱ .BTUFS 8PSLFS FUDE /PEF $POUBJOFS 3VOUJNF LVCFMFU LVCF QSPYZ BQJTFSWFS TDIFEVMFS 3FQMJDB4FU $POUSPMMFS queue ᶉLVCFMFU͕BQJTFSWFSʹϦΫΤετ͠ɺ 1PEͷ4UBUVTΛߋ৽ TUBUVTDPOEJUJPOT

ReplicaSetΛApply ʙ σϦόϦ͞ΕΔ·Ͱ .BTUFS 8PSLFS FUDE /PEF $POUBJOFS 3VOUJNF LVCFMFU LVCF QSPYZ BQJTFSWFS TDIFEVMFS 3FQMJDB4FU $POUSPMMFS queue ͜͜Ͱɺίϯςφ͕ͳΜΒ͔ͷཧ༝Ͱࢮ๢ͨ͠ͱ͠·͢

ReplicaSetΛApply ʙ σϦόϦ͞ΕΔ·Ͱ .BTUFS 8PSLFS FUDE /PEF $POUBJOFS 3VOUJNF LVCFMFU LVCF QSPYZ BQJTFSWFS TDIFEVMFS 3FQMJDB4FU $POUSPMMFS queue 1PEͷ5FSNJOBUJOH TUBUVTDPOEJUJPOT ᶊLVCFMFU͕BQJTFSWFSʹϦΫΤετ͠ɺ 1PEͷ4UBUVTΛߋ৽

ReplicaSetΛApply ʙ σϦόϦ͞ΕΔ·Ͱ .BTUFS 8PSLFS FUDE /PEF $POUBJOFS 3VOUJNF LVCFMFU LVCF QSPYZ BQJTFSWFS TDIFEVMFS 3FQMJDB4FU $POUSPMMFS queue 1PEͷ5FSNJOBUJOH ᶋ3FQMJDB4FU$POUSPMMFS͕1PEͷߋ৽Λ ݕ஌ EFMFUF ᶋ`3FQMJDB4FU$POUSPMMFS͕1PEΛ࡟আ

ReplicaSetΛApply ʙ σϦόϦ͞ΕΔ·Ͱ .BTUFS 8PSLFS FUDE /PEF $POUBJOFS 3VOUJNF LVCFMFU LVCF QSPYZ BQJTFSWFS TDIFEVMFS 3FQMJDB4FU $POUSPMMFS queue 3FDPODJMF ᶌ3FQMJDB4FU$POUSPMMFS͕3FDPODJMF͠ɺ ๬Μͩঢ়ଶ 3FQMJDBT ʹ෮چ͠ɺ 1PE͕৽͘͠࡞੒͞ΕΔ EFMFUF Ҏ߱ɺϧʔϓʜ ᶄʙᶌͷॲཧΛ܁Γฦ͢

Appendix) ιʔε ᶄ https://github.com/kubernetes/kubernetes/blob/release-1.16/pkg/controller/replicaset/replica_set.go#L487 ᶅ https://github.com/kubernetes/kubernetes/blob/v1.16.0/pkg/scheduler/eventhandlers.go#L436 ᶆ https://github.com/kubernetes/kubernetes/blob/v1.16.0/pkg/kubelet/config/apiserver.go#L33 ᶇ https://github.com/kubernetes/kubernetes/blob/v1.16.0/pkg/scheduler/scheduler.go#L535 ᶈ https://github.com/kubernetes/kubernetes/blob/release-1.16/pkg/kubelet/kuberuntime/kuberuntime_manager.go#L803 ᶉ https://github.com/kubernetes/kubernetes/blob/release-1.16/pkg/kubelet/kubelet.go#L1527 ᶊ https://github.com/kubernetes/kubernetes/blob/release-1.16/pkg/kubelet/kubelet.go#L2006 ᶋ https://github.com/kubernetes/kubernetes/blob/v1.16.0/pkg/controller/replicaset/replica_set.go#L535 ᶌ https://github.com/kubernetes/kubernetes/blob/release-1.16/pkg/controller/replicaset/replica_set.go#L487

Controllerͱίϯϙʔωϯτͨͪ ֤ίϯϙʔωϯτͷಇ͖ ɾapi-server: ResourceͷCRUD ɾscheduler: ResourceͷεέδϡʔϦϯά ɾkubelet: ίϯςφͷىಈ ɾcontroller: ResourceͷReconcile(ௐ੔) ֤ίϯϙʔωϯτ͸ͦΕͧΕͷ੹຿ʹूத = શମΛ౷཰ɾ౷੍͢Δࢦشऀ͸͍ͳ͍

Controllerͱௐ࿨ Kubernetes͸ͦΕͧΕͷίϯϙʔωϯτ͕ڠௐͯ͠ಈ͍͍ͯΔ Θ͚Ͱ͸ͳ͍ ໌ࣔతʹ໋ྩΛ͍ͯ͠ͳ͍ͷʹɺશମͱͯ͠੔߹ੑ͕औ Ε͍ͯΔ ͜͜Ͱ… ίϯϙʔωϯτͨͪΛɺͦΕͧΕҰͭͷControllerͱߟ͑Δ ͦΕͧΕͷίϯτϩʔϥ͸ɺ ͦΕͧΕͷControl LoopΛ࣮ߦ͢Δ͜ͱ͚ͩʹूத͢Δ = ෆࢥٞͱɺશମͱͯ͠ͷ੔߹ੑ͕औΕ͍ͯΔ

Kubernetes is jazz improv OrchestrationͰ͸ͳ͘ɺ Player(Controller)͕֤ʑͷԋ૗ (Control Loop)ʹूத͢Δ͜ͱͰ ଈڵͷԻָͱͯ͠ɺશମ͕੒Γཱ͍ͬͯΔ Kubernetes is more jazz improv than orchestration. Joe Beda https://blog.heptio.com/core-kubernetes-jazz-improv-over-orchestration-a7903ea92ca Co-founder Core Kubernetes: Jazz Improv over Orchestration

ͳͥControl LoopΛߦ͏ͷ͔ʁ Control LoopΛߦ͏ཧ༝Λߟ͑Δ࣌ʹɺॏཁʹͳΔ΋ͷ͕ ʮEventʯ ※ e.g. Added, Modified, Deleted, Error… ෼ࢄίϯϙʔωϯτͰ੒ΓཱͭKubernetesʹͱͬͯɺ Event͸ɺͦΕͧΕͷίϯϙʔωϯτΛͭͳ͙ॏཁͳ΋ͷ ࢀߟ: Events, the DNA of Kubernetes EventΛͲͷΑ͏ʹѻ͏͔ɺ伴ͱͳΔߟ͑ํ͕ ɾEdge-driven Triggers ɾLevel-driven Triggers https://www.mgasch.com/post/k8sevents/

Appendix) Edge vs. Level https://hackernoon.com/level-triggering-and-reconciliation-in-kubernetes-1f17fe30333d ࢀߟ: Level Triggering and Reconciliation in Kubernetes Edge-driven Triggers Level-driven Triggers EventͷൃੜʹԠͯ͡Trigger ಛఆͷঢ়ଶʹͳΔͱTrigger up down low high low

ͳͥControl LoopΛߦ͏ͷ͔ʁ ͳͥController͕Control LoopΛߦ͏ͷ͔Λߟ͑ΔͨΊʹɺ Kubernetes͕એݴతͳڍಈ(Reconcile)Ͱ͸ͳ͘ɺ खଓ͖తͳڍಈ(Procedure)Λ͢ΔͱԾఆ LJOEYYYYYYYYY NFUBEBUB OBNFYYYYYY TQFD ʜ ࣮ࡍͷKubernetes Ծఆ Reconcile Procedure

΋͠΋Controller͕खଓ͖ܕͩͬͨΒ ݱࡏͷ3FQMJDBT਺ ˢ ࡞ ੒ ˢ ࡟ ݮ खଓ͖తʹಈͨ͘ΊɺEvent͕ൃੜ͢Δͨͼʹ Edge-driven Triggerͱͯ͠ಈ͘ Ұݟ໰୊ͳ͍Α͏ʹݟ͑Δ͕ɺऑ఺΋͋Δ &WFOU

΋͠΋Reconcile͕ͳ͔ͬͨΒ ݱࡏͷ3FQMJDBT਺ ˢ ࡞ ੒ ˢ ࡟ ݮ Ұ࣌తͳωοτϫʔΫͷෆௐ΍όάͳͲͷো֐͕͋ͬͨ࣌ʹ Eventͷ৘ใ͕ࣦΘΕͯ͠·͏ ো ֐ &WFOU

Resync IntervalͱReconcile ݱࡏͷ3FQMJDBT਺ ˢ ࡞ ੒ ˢ ࡟ ݮ Resync Interval͝ͱʹReconcile(ௐ੔)Λ͢Δ͜ͱͰɺ Event͕ࣦΘΕͯ΋ཧ૝తͳঢ়ଶʹ͚ۙͮΔ ো ֐ SFTZODJOUFSWBM &WFOU Kubernetes = Edge-driven Trigger + Level-driven Trigger

ControllerΛࢧ͑Δɺ ஌͓ͬͯ͘΂͖ίϯϙʔωϯτ ʙ ϛυϧϨϕϧΞʔΩςΫνϟ ʙ

༻ޠͷ੔ཧ Kind: API Objectͷछྨ(Deployment, ServiceͳͲ) 
 Resource: Kindͱಉ͡ҙຯ߹͍Ͱ༻͍ΒΕΔɻ HTTP Endpointͱͯ͠΋ར༻͞ΕΔɻ খจࣈ͔ͭෳ਺ܗͰදݱ͞ΕΔ(pods, servicesͳͲ) Object: ࡞੒͞ΕͨAPI Object ͷ࣮ମ Metadata΍Spec, StatusͳͲͷσʔλΛอ࣋͢Δ

ControllerΛࢧ͑ΔϥΠϒϥϦ client-go Informer Lister WorkQueue api-machinery runtime.Object Scheme code-generator ϥΠϒϥϦ ίϯϙʔωϯτ লུ

Appendix) Custom Controller SDK Kubebuilder Informer ϑϨʔϜϫʔΫ ίϯϙʔωϯτ Lister Operator SDK ϥΠϒϥϦ (ϋΠϨϕϧ) controller-runtime controller-tools ϥΠϒϥϦ (ϩʔϨϕϧ) client-go api-machinery etc… Scheme runtime.Object WorkQueue etc…

ControllerΛࢧ͑ΔϥΠϒϥϦ client-go: KubernetesͷެࣜΫϥΠΞϯτϥΠϒϥϦ Kubernetesຊମͷ։ൃʹ΋࢖ΘΕ͍ͯΔ Controller࡞੒ʹ͸͔ܽͤͳ͍ϥΠϒϥϦ api-machinery: Kubernetes API Object & Kubernetes API like Object ʹඞཁͳػೳΛඋ͑ͨϥΠϒϥϦ e.g. conversion, decode, encode, etc… Controller͸API ObjectΛѻ͏ͷͰɺඞཁʹͳΔ code-generator: Informer, Lister, clientset, DeepCopyͳͲͷίʔυΛੜ੒

ControllerΛࢧ͑Δίϯϙʔωϯτ ͦΕͧΕͷৄࡉ͸ɺControllerͷ࢓૊ΈΛࢀরͭͭ͠ޙड़͠·͢ɻ Informer: ObjectͷEventΛ؂ࢹ͠ɺin-memory-cacheʹσʔλΛ֨ೲ͢Δ Lister: in-memory-cache͔ΒσʔλΛऔಘ͢Δ WorkQueue: Controller͕ॲཧ͢ΔΞΠςϜΛొ࿥͓ͯ͘͠Ωϡʔ runtime.Object: શͯͷAPI Objectڞ௨ͷInterface Scheme: Kubernetes APIͱGo TypeΛඥ෇͚Δػߏ ࠓճ͸આ໌লུ

client-go Informer ʙ ϩʔϨϕϧΞʔΩςΫνϟ ʙ

client-goͱInformer client-go Informer ϥΠϒϥϦ ίϯϙʔωϯτ Reflector DeltaFIFO Indexer Store Lister

Informer Informer͸Objectͷมߋ(Event)Λ؂ࢹ͢Δίϯϙʔωϯτ ObjectͷมߋΛ؂ࢹ͢ΔͨΊʹɺapi-serverʹঢ়ଶΛຖճ ໰͍߹ΘͤΔͱɺapi-serverʹෛՙ͕͔͔Δ ὎ in-memory-cacheʹObjectͷσʔλΛ֨ೲ͠ɺ ͦͷcacheΛࢀর͢Δ͜ͱͰapi-server΁ͷෛՙΛܰݮͤ͞Δ ղܾࡦΛ࠾༻ $POUSPMMFS $POUSPMMFS *OGPSNFS in-memory-cache watch watch

Appendix) InformerΛ࢖࣮ͬͨ૷ func main() { ... clientset, err := kubernetes.NewForConfig(config) // Create InformerFactory informerFactory := informers.NewSharedInformerFactory(clientset, time.Second*30) // Create pod informer by informerFactory podInformer := informerFactory.Core().V1().Pods() // Add EventHandler to informer podInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{ AddFunc: func(new interface{}) { log.Println("Added") }, UpdateFunc: func(old, new interface{}) { log.Println("Updated") }, DeleteFunc: func(old interface{}) { log.Println("Deleted") }, }) // Start Go routines informerFactory.Start(wait.NeverStop) // Wait until finish caching with List API informerFactory.WaitForCacheSync(wait.NeverStop) // Create Pod Lister podLister := podInformer.Lister() // Get List of pods _, err = podLister.List(labels.Nothing()) … } https://github.com/govargo/kubecontorller-book-sample-snippet/blob/master/02/podinformer/podinformer.go ᶃ kubeconfig͔ΒconfigΛੜ੒ ᶄ config͔ΒclientsetΛੜ੒ ᶅ informerFactoryੜ੒ ᶆ ᶅΛ࢖ͬͯinformerੜ੒ ᶇ EventHandlerΛ௥Ճ Add, Update, Delete࣌ʹൃՐ ᶈ InformerΛىಈ ᶉ Lister(Getter)Λੜ੒ ᶊ ListerΛ࢖ͬͯGet΍List

Appendix) Shared Informer InformerΛར༻͢Δͱ͖͸ɺInformerͦͷ΋ͷͰ͸ͳ͘ɺ Shared Informerͱݺ͹ΕΔ΋ͷΛར༻͢Δ Shared Informer͸ɺͻͱͭͷόΠφϦ಺Ͱಉ͡ResourceΛڞ༗ Ͱ͖Δ %FQMPZNFOU 3FQMJDB4FU %BFNPO4FU 4FSWJDF +PC ʜ 4IBSFE*OGPSNFSTIBSFEDBDIFGPSTBNFSFTPVSDF kube-controller-manager

https://github.com/kubernetes/sample-controller/blob/master/docs/controller-client-go.md Ҿ༻ݩ: InformerͱWorkQueue֓؍

3FqFDUPS %FMUB'*'0 RVFVF -JTU8BUDI JONFNPSZDBDIF 4UPSF *OEFYFS -JTUFS (FUPS-JTU FHDPSFW1PE (FUPS-JTU 3FRVFTU *OGPSNFS )BOEMF%FMUBT ৄࡉInformer

3FqFDUPS %FMUB'*'0 RVFVF ᶃ-JTU"OE8BUDI JONFNPSZDBDIF 4UPSF *OEFYFS *OGPSNFS )BOEMF%FMUBT ৄࡉInformer ~σʔλΛΩϟογϡ~

3FqFDUPS %FMUB'*'0 RVFVF ᶄ1PQ JONFNPSZDBDIF 4UPSF *OEFYFS *OGPSNFS )BOEMF%FMUBT 8BUDI ৄࡉInformer ~σʔλΛΩϟογϡ~

3FqFDUPS %FMUB'*'0 RVFVF ᶅ)BOEMF%FMUB JONFNPSZDBDIF 4UPSF *OEFYFS *OGPSNFS )BOEMF%FMUBT 8BUDI ৄࡉInformer ~σʔλΛΩϟογϡ~

3FqFDUPS %FMUB'*'0 RVFVF ᶆJOEFYFS"EE JONFNPSZDBDIF 4UPSF *OEFYFS *OGPSNFS )BOEMF%FMUBT 8BUDI ৄࡉInformer ~σʔλΛΩϟογϡ~

3FqFDUPS %FMUB'*'0 RVFVF JONFNPSZDBDIF 4UPSF *OEFYFS *OGPSNFS )BOEMF%FMUBT 8BUDI ᶅ)BOEMF%FMUB ৄࡉInformer ~σʔλΛΩϟογϡ~ ᶄ1PQ

3FqFDUPS %FMUB'*'0 RVFVF JONFNPSZDBDIF 4UPSF *OEFYFS *OGPSNFS )BOEMF%FMUBT 8BUDI ᶆJOEFYFS"EE ৄࡉInformer ~σʔλΛΩϟογϡ~

3FqFDUPS %FMUB'*'0 RVFVF JONFNPSZDBDIF 4UPSF *OEFYFS *OGPSNFS )BOEMF%FMUBT 8BUDI ৄࡉInformer ~σʔλΛऔΓग़͢~ -JTUFS (FUPS-JTU 3FRVFTU

3FqFDUPS %FMUB'*'0 RVFVF JONFNPSZDBDIF 4UPSF *OEFYFS *OGPSNFS )BOEMF%FMUBT 8BUDI JOEFYFS(FU#Z,FZ PS JOEFYFS-JTU ৄࡉInformer ~σʔλΛऔΓग़͢~ -JTUFS (FUPS-JTU 3FRVFTU

Appendix) Informer cache ιʔε ᶃ https://github.com/kubernetes/client-go/blob/release-13.0/tools/cache/reflector.go#L188 ᶄ https://github.com/kubernetes/client-go/blob/release-13.0/tools/cache/controller.go#L153 ᶅ https://github.com/kubernetes/client-go/blob/release-13.0/tools/cache/shared_informer.go#L455 ᶆ https://github.com/kubernetes/client-go/blob/release-13.0/tools/cache/shared_informer.go#L464

Informerͱίϯϙʔωϯτ Informer: ObjectͷEventΛ؂ࢹ͠ɺin-memory-cacheʹσʔλΛ֨ೲ͢Δ Reflector: api-serverͷEventΛ؂ࢹ͢Δ DeltaFIFO: ObjectͷEvent͕ൃੜ͢Δͨͼʹ࢖͏FIFOΩϡʔ Indexer: in-memory-cache΁ͷॻ͖ࠐΈ΍ಡΈࠐΈΛߦ͏ Store: in-memory-cache Lister: in-memory-cache͔ΒIndexerܦ༝ͰσʔλΛऔಘ͢Δ

client-go WorkQueue ʙ ϩʔϨϕϧΞʔΩςΫνϟ ʙ

client-goͱWorkQueue client-go WorkQueue ϥΠϒϥϦ ίϯϙʔωϯτ RateLimitingQueue DelayedQueue

WorkQueue WorkQueue͸ɺDeltaFIFOͱ͸ҟͳΔ΋͏ͻͱͭͷΩϡʔ WorkQueue͸ɺControl LoopͷΞΠςϜΛཷΊ͓ͯͨ͘Ίʹ ࢖ΘΕΔ ඪ४ControllerͰ͸ɺInformerͷEventHandler͕ൃՐ͢Δͱɺ WorkQueueʹΞΠςϜΛenqueue͢Δ࣮૷ʹͳ͍ͬͯΔ Event $POUSPMMFS Added Updated Deleted WorkQueue

Appendix) WorkQueueΛ࢖࣮ͬͨ૷ func main() { ... clientset, err := kubernetes.NewForConfig(config) // Create InformerFactory informerFactory := informers.NewSharedInformerFactory(clientset, time.Second*30) // Create pod informer by informerFactory podInformer := informerFactory.Core().V1().Pods() // Create RateLimitQueue queue := workqueue.NewRateLimitingQueue(workqueue.DefaultControllerRateLimiter()) // shutdown when process ends defer queue.ShutDown() // Add EventHandler to informer podInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{ AddFunc: func(old interface{}) { var key string var err error if key, err = cache.MetaNamespaceKeyFunc(old); err != nil { runtime.HandleError(err) return } queue.Add(key) log.Println("Added: " + key) }, UpdateFunc: func(old, new interface{}) { … }, DeleteFunc: func(old interface{}) { … }, }) … } https://github.com/govargo/kubecontorller-book-sample-snippet/blob/master/02/workqueue/enqueuePod.go ᶃ kubeconfig͔ΒconfigΛੜ੒ ᶄ config͔ΒclientsetΛੜ੒ ᶅ informerFactoryੜ੒ ᶆ ᶅΛ࢖ͬͯinformerੜ੒ ᶇ EventHandlerΛ௥Ճ Add, Update, Delete࣌ʹൃՐ ᶈ InformerΛىಈ ᶉ Lister(Getter)Λੜ੒ ᶊ ListerΛ࢖ͬͯGet΍List ᶇ WorkQueueੜ੒

3FqFDUPS %FMUB'*'0 RVFVF -JTU8BUDI 3FTPVSDF &WFOU )BOEMFS JONFNPSZDBDIF TUPSF *OEFYFS 8PSL2VFVF 1SPDFTT *UFN $POUSPMMFSϩδοΫ *OGPSNFS &WFOU)BOEMFS ৄࡉWorkQueue

3FqFDUPS %FMUB'*'0 RVFVF 3FTPVSDF &WFOU )BOEMFS JONFNPSZDBDIF TUPSF *OEFYFS 8PSL2VFVF 1SPDFTT *UFN $POUSPMMFSϩδοΫ *OGPSNFS &WFOU)BOEMFS ৄࡉWorkQueue ~Enqueue~ &WFOU -JTU8BUDI

3FqFDUPS %FMUB'*'0 RVFVF 3FTPVSDF &WFOU )BOEMFS JONFNPSZDBDIF TUPSF *OEFYFS 8PSL2VFVF 1SPDFTT *UFN $POUSPMMFSϩδοΫ *OGPSNFS &WFOU)BOEMFS ᶃ8BUDI ৄࡉWorkQueue ~Enqueue~

3FqFDUPS %FMUB'*'0 RVFVF 3FTPVSDF &WFOU )BOEMFS JONFNPSZDBDIF TUPSF *OEFYFS 8PSL2VFVF 1SPDFTT *UFN $POUSPMMFSϩδοΫ *OGPSNFS &WFOU)BOEMFS ৄࡉWorkQueue ~Enqueue~ 8BUDI ᶄ1PQ

3FqFDUPS %FMUB'*'0 RVFVF 3FTPVSDF &WFOU )BOEMFS JONFNPSZDBDIF TUPSF *OEFYFS 8PSL2VFVF 1SPDFTT *UFN $POUSPMMFSϩδοΫ *OGPSNFS &WFOU)BOEMFS ৄࡉWorkQueue ~Enqueue~ 8BUDI ᶅ "EE'VOD 6QEBUF'VOD %FMFUF'VOD

3FqFDUPS %FMUB'*'0 RVFVF 3FTPVSDF &WFOU )BOEMFS JONFNPSZDBDIF TUPSF *OEFYFS 8PSL2VFVF 1SPDFTT *UFN $POUSPMMFSϩδοΫ *OGPSNFS &WFOU)BOEMFS ৄࡉWorkQueue ~Enqueue~ 8BUDI namesapce/name e.g. default/nginx ᶆXPSLRVFVF"EE

3FqFDUPS %FMUB'*'0 RVFVF 3FTPVSDF &WFOU )BOEMFS JONFNPSZDBDIF TUPSF *OEFYFS 8PSL2VFVF 1SPDFTT *UFN $POUSPMMFSϩδοΫ *OGPSNFS &WFOU)BOEMFS ৄࡉWorkQueue ~Enqueue~ 8BUDI ᶅ "EE'VOD 6QEBUF'VOD %FMFUF'VOD

3FqFDUPS %FMUB'*'0 RVFVF 3FTPVSDF &WFOU )BOEMFS JONFNPSZDBDIF TUPSF *OEFYFS 8PSL2VFVF 1SPDFTT *UFN $POUSPMMFSϩδοΫ *OGPSNFS &WFOU)BOEMFS ৄࡉWorkQueue ~Enqueue~ 8BUDI ᶆXPSLRVFVF"EE

3FqFDUPS %FMUB'*'0 RVFVF 3FTPVSDF &WFOU )BOEMFS JONFNPSZDBDIF TUPSF *OEFYFS 8PSL2VFVF 1SPDFTT *UFN $POUSPMMFSϩδοΫ *OGPSNFS &WFOU)BOEMFS ৄࡉWorkQueue ~Dequeue~ 8BUDI ᶇXPSLRVFVF(FU

Appendix) Informer enqueue ιʔε ᶃ https://github.com/kubernetes/client-go/blob/master/tools/cache/reflector.go#L267 ᶄ https://github.com/kubernetes/client-go/blob/release-13.0/tools/cache/controller.go#L153 ᶅ
 https://github.com/kubernetes/client-go/blob/release-13.0/tools/cache/controller.go#L198 https://github.com/kubernetes/kubernetes/blob/release-1.16/pkg/controller/replicaset/replica_set.go#L153 ※ ReplicaSet Controllerͷ৔߹ ᶆ https://github.com/kubernetes/kubernetes/blob/release-1.16/pkg/controller/replicaset/replica_set.go#L417 ※ ReplicaSet Controllerͷ৔߹ ᶇ https://github.com/kubernetes/kubernetes/blob/release-1.16/pkg/controller/replicaset/replica_set.go#L438 ※ ReplicaSet Controllerͷ৔߹

Appendix) InformerͱResync Period Informer͸ىಈ࣌ʹɺResync Periodͱ͍͏Ҿ਺Λࢦఆ͢Δ Informer͸api-server͔ΒObjectͷมߋΛ؂ࢹ͍ͯ͠Δ Resync PeriodΛա͗ΔͱɺԿͷEvent͕ൃੜ͍ͯ͠ͳ͍ͯ͘΋ UpdateFunc͕ݺͼग़͞Εͯɺ݁ՌReconcile͕࣮ߦ͞ΕΔ ※͜ͷ࣌ɺResync͸in-memory-cacheΛࢀর͢Δɻ Resync(cacheͷࢀর)ͱRelist(api-server΁ͷ໰͍߹Θͤ)͸ผ෺ informer.Start SFTZODQFSJPE List Watch Event Reflector Added Updated Updated Added AddFunc UpdateFunc AddFunc UpdateFunc Handler

ControllerͷCycle Main Logic

*OGPSNFS 1SPDFTT *UFN 3FTPVSDF &WFOU )BOEMFS 8PSL2VFVF ControllerͷCycle Informer + WorkQueue + Controller ͷશମͷCycleΛ֬ೝ $POUSPMMFS ϝΠϯϩδοΫ

*OGPSNFS 1SPDFTT *UFN 3FTPVSDF &WFOU )BOEMFS ControllerͷCycle XBUDI 8PSL2VFVF ʲԾఆʳ Pod͕͢Ͱʹ2ͭ͋Δ ͔͜͜ΒUpdate Event͕ൃੜ͢Δ

*OGPSNFS 1SPDFTT *UFN 3FTPVSDF &WFOU )BOEMFS ControllerͷCycle 6QEBUF XBUDI 8PSL2VFVF

*OGPSNFS 1SPDFTT *UFN 3FTPVSDF &WFOU )BOEMFS ControllerͷCycle XBUDI BEE'VOD VQEBUF'VOD EFMFUF'VOD ᶄ 8PSL2VFVF

*OGPSNFS 1SPDFTT *UFN 3FTPVSDF &WFOU )BOEMFS ControllerͷCycle XBUDI ᶅXPSL2VFVF"EE 8PSL2VFVF

*OGPSNFS 1SPDFTT *UFN 3FTPVSDF &WFOU )BOEMFS ControllerͷCycle XBUDI ᶅXPSL2VFVF"EE 8PSL2VFVF

*OGPSNFS 1SPDFTT *UFN 3FTPVSDF &WFOU )BOEMFS ControllerͷCycle XBUDI ᶆXPSL2VFVF(FU 8PSL2VFVF

*OGPSNFS 1SPDFTT *UFN 3FTPVSDF &WFOU )BOEMFS ControllerͷCycle XBUDI ᶆXPSL2VFVF(FU 8PSL2VFVF

*OGPSNFS 1SPDFTT *UFN 3FTPVSDF &WFOU )BOEMFS ControllerͷCycle XBUDI ᶇ4ZOD)BOEMFS 3FDPODJMF 8PSL2VFVF

*OGPSNFS 1SPDFTT *UFN 3FTPVSDF &WFOU )BOEMFS ControllerͷCycle XBUDI ᶈXPSL2VFVF'PSHFU ᶉXPSL2VFVF%POF Reconcile͕ਖ਼ৗऴྃͨ͠Β ΞΠςϜΛ8PSL2VFVF͔Βআ֎ 8PSL2VFVF

*OGPSNFS 1SPDFTT *UFN 3FTPVSDF &WFOU )BOEMFS ControllerͷCycle XBUDI ᶇ`XPSL2VFVF"EE3BUF-JNJUFE Reconcile͕Τϥʔ 8PSL2VFVFʹ3FRVFVFͯ͠ɺ3FDPODJMFΛ࠶ࢼߦ 8PSL2VFVF

*OGPSNFS 1SPDFTT *UFN 3FTPVSDF &WFOU )BOEMFS ControllerͷCycle XBUDI ᶇ`XPSL2VFVF"EE3BUF-JNJUFE Reconcile͕Τϥʔ 8PSL2VFVFʹ3FRVFVFͯ͠ɺ3FDPODJMFΛ࠶ࢼߦ 8PSL2VFVF

*OGPSNFS 1SPDFTT *UFN 3FTPVSDF &WFOU )BOEMFS ControllerͷCycle Event͕ൃੜ͢ΔͨͼʹWorkQueueʹΞΠςϜ͕ೖΓଓ͚Δ WorkQueueʹஷ·ͬͨΞΠςϜΛReconcileͰॲཧ͠ଓ͚Δ ͜ͷϧʔϓ͕ɺController͕ࢭ·Δ·ͰԆʑͱଓ͘ 8PSL2VFVF

Controllerͷجຊઓུ Read͸In-memory-cache͔ΒɺWrite͸api-server΁ ※cacheΛ͍͡ΔͱҰ؏ੑΛอͭͷ͕೉͍͠ͷͰɺ Write͢Δͱ͖͸ɺҰճDeepCopy͔ͯ͠Βߋ৽͢Δ e.g. kubernetes/pkg/controller/replicaset/replica_set.go rs = rs.DeepCopy() newStatus := calculateStatus(rs, filteredPods, manageReplicasErr) // Always updates status as pods come up or die. updatedRS, err := updateReplicaSetStatus(rsc.kubeClient.AppsV1(). ὎ ReplicaSets(rs.Namespace), rs, newStatus) https://github.com/kubernetes/kubernetes/blob/release-1.15/pkg/controller/replicaset/replica_set.go#L611

XPSLFS XPSLFS QSPDFTT/FYU8PSL*UFN TZOD)BOEMFS ControllerͷMain Logic worker: processNextWorkItemΛແݶϧʔϓ processNextWorkItem: WorkQueueΛૢ࡞(Get, Add)ͯ͠ ReconcileΛݺͼग़͢ syncHandler: Reconcileʹ͋ͨΔϝΠϯϩδοΫ Add TZOD)BOEMFS Update Delete Event Reconcile Eventͷछྨʹ͔͔ΘΒͣɺ Reconcile͢Δ

Appendix) ReplicaSet Controller worker: processNextWorkItemΛແݶϧʔϓ processNextWorkItem: WorkQueueΛૢ࡞(Get, Add)ͯ͠ ReconcileΛݺͼग़͢ syncReplicaSet: Reconcileʹ͋ͨΔϝΠϯϩδοΫ XPSLFS XPSLFS QSPDFTT/FYU8PSL*UFN TZOD3FQMJDB4FU https://github.com/kubernetes/kubernetes/blob/release-1.16/pkg/controller/replicaset/replica_set.go#L432 https://github.com/kubernetes/kubernetes/blob/release-1.16/pkg/controller/replicaset/replica_set.go#L437 https://github.com/kubernetes/kubernetes/blob/release-1.16/pkg/controller/replicaset/replica_set.go#L562 ReplicaSet Controllerͷιʔε v1.16 ※Deployment΋ྨࣅͷߏ଄Λ͍ͯ͠Δ

Appendix) in-memory-cacheͱetcdͷಉظ in-memory-cache͸InformerΛ࢖ͬͯඇಉظʹetcdͷ৘ใΛ Ωϟογϡ͍ͯ͠Δ ʮΩϟογϡͱetcdͰ৘ใ͕ζϨͳ͍͔ʁʯͱࢥ͏͔΋͠Εͳ ͍͕ɺKubernetesͰ͸resourceVersionͱ͍͏࢓૊Έ͕͋Δɻ resourceVersion͕ҟͳΔͱΤϥʔʹͳͬͯɺRecocileΛ࠶ࢼߦ ͢ΔͷͰɺζϨ͍ͯͯ΋໰୊͸ͳ͍ Rv2 Rv1 Update Rv2 version too old Requeue Reconcile (retry)

༻ޠ੔ཧ(ৼΓฦΓ) Informer: ObjectͷEventΛ؂ࢹ͠ɺin-memory-cacheʹσʔλΛ֨ೲ͢Δ EventHandlerΛ௨ͯ͡ɺWorkQueueʹΞΠςϜΛ௥Ճ͢Δ Lister: ObjectΛऔಘ͍ͨ࣌͠ in-memory-cache͔ΒσʔλΛऔಘ͢Δ WorkQueue: Controller͕ॲཧ͢ΔΞΠςϜΛొ࿥͓ͯ͘͠Ωϡʔ ͜ͷΩϡʔʹஷ·͍ͬͯΔΞΠςϜ͕Reconcileͷର৅ ReconcileͰΤϥʔ͕ൃੜͨ͠৔߹͸ɺRequeue͞Εɺ ControllerଆͰReconcileΛ࠶ࢼߦ͢Δ

Controllerͷ·ͱΊ

Controllerͷ·ͱΊ ɾController͸ɺControl Loop(Reconciliation Loop)ʹΑͬͯ એݴతͳAPIΛ࣮ݱ ɾ෼ࢄίϯϙʔωϯτ͸ͦΕͧΕಠཱ͓ͯ͠Γɺ Event͕ίϯϙʔωϯτؒΛ݁ͼ͚ͭΔ ɾclient-go, apimachinery, code-generator౳͕ControllerΛࢧ͑Δ ɾInformer͸ೋͭͷ໨తΛ࣋ͭ ᶃ in-memory-cacheʹObjectͷσʔλΛ֨ೲ͢Δ ᶄ EventHandlerܦ༝ͰWorkQueueʹΞΠςϜΛ֨ೲ͢Δ ɾWorkQueueʹஷΊΒΕͨΞΠςϜ͸ReconcileͰॲཧ͞ΕΔ ※ ͜ΕΒΛ஌Βͳͯ͘΋ɺController͸ར༻Ͱ͖·͢

Deep Dive΁ͷಓ ʙ ΋ͬͱਂ͘஌Γ͍ͨਓ޲͚ʹ ʙ ɾSample ControllerΛಈ͔͢ ɾKubernetesຊମͷ࣮૷ΛݟͯΈΔ - Deployment Controller - ReplicaSet Controller ɾCustom ControllerΛ࡞ͬͯΈΔ(+ CRD) ϦϯΫ: https://github.com/kubernetes/sample-controller mkdir -p $GOPATH/src/k8s.io && cd $GOPATH/src/k8s.io && git clone https://github.com/kubernetes/sample-controller.git export GO111MODULE=on go build -o sample-controller . ./sample-controller -kubeconfig $HOME/.kube/config https://github.com/kubernetes/kubernetes/blob/release-1.16/pkg/controller/deployment/deployment_controller.go https://github.com/kubernetes/kubernetes/blob/release-1.16/pkg/controller/replicaset/replica_set.go

Programming Kubernetes https://programming-kubernetes.info/ ঺հϒϩάࢀߟ: https://go-vargo.hatenablog.com/entry/2019/08/05/201546 O’Reilly Media, Inc.ΑΓग़൛ ʮProgramming Kubernetesʯ Stefan Schimanski, Michael Hausenblasஶ 1~2ষ: Kubernetesͷجຊࢥ૝, API Object 3ষ: client-go 4ষ: CRD 5ষ: code-generator 6~7ষ: Custom Controller 8~9ষ: Custom API Server, CRDԠ༻ػೳ

Thank you

Reference

Reference ɾWeb Article - https://kubernetes.io/docs/concepts/architecture/nodes/ - https://kubernetes.io/docs/concepts/workloads/controllers/garbage-collection/ - https://github.com/kubernetes/community/blob/master/contributors/devel/sig-api-machinery/controllers.md - A deep dive into Kubernetes controllers (https://engineering.bitnami.com/articles/a-deep-dive-into-kubernetes-controllers.html) - Core Kubernetes: Jazz Improv over Orchestration (https://blog.heptio.com/core-kubernetes-jazz-improv-over-orchestration-a7903ea92ca) - Events, the DNA of Kubernetes(https://www.mgasch.com/post/k8sevents/) ɾPresentation - Kubernete Meetup Tokyo #18 - Kubebuilder/controller-runtime ೖ໳ (https://www.slideshare.net/pfi/kubernete-meetup-tokyo-18-kubebuildercontrollerruntime) - KubernetesͷιʔείʔυϦʔσΟϯάೖ໳ (https://speakerdeck.com/smatsuzaki/kubernetesfalsesosukodorideinguru-men) ɾBook - Programming Kubernetes (https://programming-kubernetes.info/)

Reference ɾRepository - Kubernetes(https://github.com/kubernetes/kubernetes) - Sample Controller(https://github.com/kubernetes/sample-controller) - client-go(https://github.com/kubernetes/client-go) - apimachinery(https://github.com/kubernetes/apimachinery) - codegenerator(https://github.com/kubernetes/code-generator) - what-happens-when-k8s(https://github.com/jamiehannaford/what-happens-when-k8s)