OReilly.Kubernetes.Operators.2020.2.pdf

【实例简介】

Operators are a way of packaging, deploying, and managing Kubernetes applications. A Kubernetes application doesn’t just run on Kubernetes; it’s composed and managed in Kubernetes terms. Operators add application-specific operational knowledge to a Kubernetes cluster, making it easier to automate complex, stateful applications and to augment the platform. Operators can coordinate application upgrades seamlessly, react to failures automatically, and streamline repetitive maintenance like backups.

Think of Operators as site reliability engineers in software. They work by extending the Kubernetes control plane and API, helping systems integrators, cluster administrators, and application developers reliably deploy and manage key services and components. Using real-world examples, authors Jason Dobies and Joshua Wood demonstrate how to use Operators today and how to create Operators for your applications with the Operator Framework and SDK.

• Learn how to establish a Kubernetes cluster and deploy an Operator
• Examine a range of Operators from usage to implementation
• Explore the three pillars of the Operator Framework: the Operator SDK, the Operator
• Lifecycle Manager, and Operator Metering
• Build Operators from the ground up using the Operator SDK
• Build, package, and run an Operator in development, testing, and production phases
• Learn how to distribute your Operator for installation on Kubernetes clusters

【实例截图】

【核心代码】

Table of Contents
Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
1. Operators Teach Kubernetes New Tricks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
How Kubernetes Works 1
Example: Stateless Web Server 3
Stateful Is Hard 4
Operators Are Software SREs 5
How Operators Work 5
Kubernetes CRs 6
How Operators Are Made 6
Example: The etcd Operator 7
The Case of the Missing Member 7
Who Are Operators For? 8
Operator Adoption 8
Let’s Get Going! 9
2. Running Operators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Setting Up an Operator Lab 11
Cluster Version Requirements 11
Authorization Requirements 12
Standard Tools and Techniques 13
Suggested Cluster Configurations 13
Checking Your Cluster Version 14
Running a Simple Operator 15
A Common Starting Point 15
Fetching the etcd Operator Manifests 16
CRs: Custom API Endpoints 16
Who Am I: Defining an Operator Service Account 17
vii
Deploying the etcd Operator 19
Declaring an etcd Cluster 20
Exercising etcd 21
Scaling the etcd Cluster 22
Failure and Automated Recovery 23
Upgrading etcd Clusters 24
Cleaning Up 26
Summary 27
3. Operators at the Kubernetes Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Standard Scaling: The ReplicaSet Resource 29
Custom Resources 30
CR or ConfigMap? 30
Custom Controllers 31
Operator Scopes 31
Namespace Scope 31
Cluster-Scoped Operators 32
Authorization 32
Service Accounts 32
Roles 33
RoleBindings 33
ClusterRoles and ClusterRoleBindings 33
Summary 34
4. The Operator Framework. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Operator Framework Origins 35
Operator Maturity Model 36
Operator SDK 36
Installing the Operator SDK Tool 37
Operator Lifecycle Manager 37
Operator Metering 38
Summary 39
5. Sample Application: Visitors Site. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Application Overview 41
Installation with Manifests 43
Deploying MySQL 43
Backend 45
Frontend 47
Deploying the Manifests 49
Accessing the Visitors Site 49
Cleaning Up 49
viii | Table of Contents
Summary 50
6. Adapter Operators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Helm Operator 53
Building the Operator 53
Fleshing Out the CRD 57
Reviewing Operator Permissions 57
Running the Helm Operator 57
Ansible Operator 58
Building the Operator 58
Fleshing Out the CRD 60
Reviewing Operator Permissions 60
Running the Ansible Operator 60
Testing an Operator 61
Summary 62
Resources 62
7. Operators in Go with the Operator SDK. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Initializing the Operator 64
Operator Scope 64
Custom Resource Definitions 66
Defining the Go Types 67
The CRD Manifest 68
Operator Permissions 68
Controller 69
The Reconcile Function 71
Operator Writing Tips 72
Retrieving the Resource 72
Child Resource Creation 73
Child Resource Deletion 76
Child Resource Naming 77
Idempotency 77
Operator Impact 78
Running an Operator Locally 79
Visitors Site Example 80
Summary 81
Resources 81
8. Operator Lifecycle Manager. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
OLM Custom Resources 83
ClusterServiceVersion 84
CatalogSource 84
Table of Contents | ix
Subscription 85
InstallPlan 85
OperatorGroup 85
Installing OLM 86
Using OLM 88
Exploring the Operator 92
Deleting the Operator 93
OLM Bundle Metadata Files 94
Custom Resource Definitions 94
Cluster Service Version File 95
Package Manifest File 95
Writing a Cluster Service Version File 95
Generating a File Skeleton 95
Metadata 97
Owned CRDs 98
Required CRDs 101
Install Modes 102
Versioning and Updating 102
Writing a Package Manifest File 103
Running Locally 104
Prerequisites 104
Building the OLM Bundle 107
Installing the Operator Through OLM 109
Testing the Running Operator 111
Visitors Site Operator Example 111
Summary 111
Resources 111
9. Operator Philosophy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
SRE for Every Application 113
Toil Not, Neither Spin 114
Automatable: Work Your Computer Would Like 114
Running in Place: Work of No Enduring Value 114
Growing Pains: Work That Expands with the System 115
Operators: Kubernetes Application Reliability Engineering 115
Managing Application State 116
Golden Signals Sent to Software 116
Seven Habits of Highly Successful Operators 118
Summary 119
10. Getting Involved. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Feature Requests and Reporting Bugs 121
x | Table of Contents
Contributing 122
Sharing Operators 123
Summary 123
A. Running an Operator as a Deployment Inside a Cluster. . . . . . . . . . . . . . . . . . . . . . . . . . 125
B. Custom Resource Validation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
C. Role-Based Access Control (RBAC). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133