Kubernetes RBAC in microservices

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Mercari Meetup for Microservices Platform, Jul 19, 2018 Kubernetes RBAC in microservices

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2 About me @spesnova SRE at Mercari Microservices Platform team Kubernetes Tokyo Community Organizer

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3 Agenda 1. AuthN/Z in Kubernetes 2. Design Principles 3. RBAC Policy

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AuthN/Z in Kubernetes

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What is Kubernetes RBAC?

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6 What is Kubernetes RBAC? Role Based Access Control

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7 a method of regulating access to computer or network resources based on the roles of individual users within an enterprise What is Kubernetes RBAC? https://kubernetes.io/docs/reference/access-authn-authz/rbac/

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8 Role based? ● User based - easy but inefficient ● Team based - intermediate ● Role based - efficient but not easy

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9 4 Objects in Kubernetes RBAC Roles ClusterRoles RoleBindings ClusterRoleBindings

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Roles and ClusterRoles

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11 Roles and ClusterRoles Roles ClusterRoles Verbs Resources Verbs Resources

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12 Verbs Verbs “create” “get”, “list” “update” “patch” “delete”, “deletecollection” “watch”

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13 Resources Resources “pods” “deployments” “configmaps” “secrets” “namespaces” “resourcequotas” “nodes”

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14 Namespace scoped resources Namespace scoped resources “pods” “deployments” “configmaps” “secrets” “namespaces” “resourcequotas” “nodes”

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15 Cluster scoped resources Cluster scoped resources “pods” “deployments” “configmaps” “secrets” “namespaces” “resourcequotas” “nodes”

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16 Roles example - a role can read pods in default namespace kind: Role apiVersion: rbac.authorization.k8s.io/v1 metadata: namespace: default name: pod-reader rules: - apiGroups: [""] # "" indicates the core API group resources: ["pods"] verbs: ["get", "watch", "list"]

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17 ClusterRoles example - a clusterrole can read pods in all namespaces kind: ClusterRole apiVersion: rbac.authorization.k8s.io/v1 metadata: # “namespace” is not required name: global-pod-reader rules: - apiGroups: [""] # "" indicates the core API group resources: ["pods"] verbs: ["get", "watch", "list"]

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RoleBindingss and ClusterRoleBindings

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19 4 Objects in Kubernetes RBAC Roles ClusterRoles RoleBindings ClusterRoleBindings

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20 RoleBindings and ClusterRoleBindings RoleBindings ClusterRoleBindings Role/ClusterRole Subjects ClusterRole Subjects

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21 Subjects Subjects “User” “Group” “ServiceAccount”

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22 RoleBinding example - spesnova can read pods in default namespace kind: RoleBinding apiVersion: rbac.authorization.k8s.io/v1 metadata: name: read-pods namespace: default subjects: - kind: User name: spesnova@example.com apiGroup: rbac.authorization.k8s.io roleRef: kind: Role name: pod-reader apiGroup: rbac.authorization.k8s.io

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23 RoleBinding example - spesnova can read pods in default namespace kind: RoleBinding apiVersion: rbac.authorization.k8s.io/v1 metadata: name: read-pods namespace: default subjects: - kind: User name: spesnova@example.com apiGroup: rbac.authorization.k8s.io roleRef: kind: ClusterRole name: global-pod-reader apiGroup: rbac.authorization.k8s.io

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24 RoleBinding example - spesnova can read pods in all namespace kind: ClusterRoleBinding apiVersion: rbac.authorization.k8s.io/v1 metadata: name: read-pods # “namespace” is not required subjects: - kind: User name: spesnova@example.com apiGroup: rbac.authorization.k8s.io roleRef: kind: ClusterRole name: global-pod-reader apiGroup: rbac.authorization.k8s.io

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Default ClusterRoles

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26 Default ClusterRoles / admin Allows read/write access to most resources in a namespace, including the ability to create roles and rolebindings within the namespace. https://kubernetes.io/docs/reference/access-authn-authz/rbac/

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27 Default ClusterRoles / edit Allows read/write access to most objects in a namespace. It does not allow viewing or modifying roles or rolebindings. https://kubernetes.io/docs/reference/access-authn-authz/rbac/

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28 Default ClusterRoles / view Allows read-only access to see most objects in a namespace. It does not allow viewing roles or rolebindings. It does not allow viewing secrets, since those are escalating. https://kubernetes.io/docs/reference/access-authn-authz/rbac/

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29 How to test RBAC settings? $ kubectl auth can-i get pods / --namespace=default / --as=spesnova@example.com yes

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Authentication in GKE

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31 Authentication in GKE (skip details because of time limitation) Google OAuth2 (OpenID Connect Tokens authentication)

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Design Principles

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End-to-End Ownership

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34 The purpose of microservices Getting agility at large scale org&system

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35 The purpose of microservices How to get agility? How to make people high-performer?

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With Great power comes great responsibility

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Great power requires great responsibility

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38 I was in an organization holding 1000+ engineers Small responsibility makes people low-performer

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39 Great responsibility means... End-to-End ownership

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40 Our platform mission Build system & organization which people have E2E ownership

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Hide complexity behind infrastructure

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42 Hide complexity behind infrastructure Microservices architecture itself is already complicated

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43 Microservices architecture

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44 Microservices architecture Each microservices become simple but operations become complex

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45 Hide complexity behind infrastructure Keep each components simple Hide complexity behind infrastructure

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46 Hide complexity behind infrastructure Make each RBAC policy simple Handle the complexity with tools

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RBAC Policy

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Namespace/Team per microservices

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49 Our microservices conventions Team per microservice Namespace per microservice

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50 Namespace per microservice microservice A microservice B microservice C Kubernetes Cluster

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51 Namespace per microservice microservice A microservice B microservice C namespace A namespace B namespace C Kubernetes Cluster

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52 Namespace and Team per microservice microservice A microservice B microservice C namespace A namespace B namespace C Kubernetes Cluster team A team B team C

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Give namespace-admin

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54 Give namespace-admin = End-to-End ownership microservice A microservice B microservice C namespace A namespace B namespace C Kubernetes Cluster team A team B team C

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55 Give namespace-admin = End-to-End ownership microservice A microservice B microservice C namespace A namespace B namespace C Kubernetes Cluster team A team B team C RoleBiding A RoleBiding B RoleBiding C

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56 RoleBinding example - hello team members are namespace admin in hello ns kind: RoleBinding apiVersion: rbac.authorization.k8s.io/v1 metadata: name: service-admins namespace: hello subjects: - kind: User name: spesnova@example.com apiGroup: rbac.authorization.k8s.io roleRef: kind: ClusterRole name: admin apiGroup: rbac.authorization.k8s.io

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Microservice diversity

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58 Microservice diversity Roles namespace A Kubernetes Cluster team A / service Admins RoleBindings Secrets Deployments ConfigMaps ClusterRoleBiding admins

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59 Some teams want “read-only” namespace A Kubernetes Cluster team A / service Viewers Deployments ConfigMaps ClusterRoleBiding viewers

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60 RoleBinding example - some members are namespace view in hello namespace kind: RoleBinding apiVersion: rbac.authorization.k8s.io/v1 metadata: name: service-viewers namespace: hello subjects: - kind: User name: dtan4@example.com apiGroup: rbac.authorization.k8s.io roleRef: kind: ClusterRole name: view apiGroup: rbac.authorization.k8s.io

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61 Some teams want to restrict RBAC editing namespace A Kubernetes Cluster team A / service Editors Deployments ConfigMaps ClusterRoleBiding editors Secrets

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62 RoleBinding example - some members are namespace edit in hello namespace kind: RoleBinding apiVersion: rbac.authorization.k8s.io/v1 metadata: name: service-editors namespace: hello subjects: - kind: User name: babarot@example.com apiGroup: rbac.authorization.k8s.io roleRef: kind: ClusterRole name: edit apiGroup: rbac.authorization.k8s.io

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63 Using default ClusterRoles Accept diversity but keep it simple

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64 Microservice diversity If required, they can create custom roles

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65 But...avoid to create custom role as possible (RBAC rabbit hole) $ kubectl get clusterroles/admin -o yaml | wc -l 457 457 lines yaml !!

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Handle complexity with tools

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67 Our microservices conventions Team per microservice Namespace per microservice

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68 Namespace and Team per microservice microservice A microservice B microservice C namespace A namespace B namespace C Kubernetes Cluster team A team B team C

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69 Namespace and Team per microservice, then... So many namespaces and teams!!

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70 We aim to have 200+ microservices Impossible to create hundreds RoleBindings by hand

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71 Too many namespaces and teams? No, it is intended

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72 Hide complexity behind infrastructure Keep each components simple Hide complexity behind infrastructure

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73 Keep each components simple If multiple services/teams in a namespace, RBAC must become much more complicated

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74 Hide complexity behind infrastructure Keep each components simple Hide complexity behind infrastructure

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75 Microservice Starter Kit An internal Terraform module to reduce provisioning burdun from developers and manage infrastructure as code https://speakerdeck.com/b4b4r07/terraform-ops-for-microservices?slide=13

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76 Automate RoleBindings creation with microservice-starter-kit (WIP) module “hello-service” { ... service_admins = [ "spesnova@example.com", "tcnksm@example.com", "b4b4r07@example.com", ] ...

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77 Automate RoleBindings creation with microservice-starter-kit (WIP) … service_editors = [ "dtan4@example.com", ] … service_viewers = [ "terry@example.com", ]

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78 Automate RoleBindings creation with microservice-starter-kit (WIP) microservice A microservice B microservice C namespace A namespace B namespace C Kubernetes Cluster team A team B team C RoleBiding A RoleBiding B RoleBiding C

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79 Need to implement kubernetes_rolebinding Terraform resource (WIP) No official resource!

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Recap

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81 Recap Delegation Simplicity Tools Keep RBAC policy simple as possible Delegate enough permission to teams Handle complexity with tools

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End