使用Kubernetes为Golang创建TODO API

必要组件列表：

• 本地安装的Docker

• Kubernetes集群

• 高朗

• 集成开发环境

创建集群

使用k3d创建一个新集群：

export KUBECONFIG="$(k3d get-kubeconfig --name='k3s-default')"

kubectl get node
NAME                     STATUS   ROLES    AGE   VERSION
k3d-k3s-default-server   Ready    master   48s   v1.17.0+k3s.1

安装arkade

curl -sLS https://dl.get-arkade.dev | sudo sh

arkade install postgresql
===================================================================== = PostgreSQL has been installed.                                    =
=====================================================================

CREATE TABLE todo (
 id              INT GENERATED ALWAYS AS IDENTITY,
 description     text NOT NULL,
 created_date    timestamp NOT NULL,
 completed_date  timestamp NOT NULL
);

export POSTGRES_PASSWORD=$(kubectl get secret --namespace default postgresql -o jsonpath="{.data.postgresql-password}" | base64 --decode)
kubectl run postgresql-client --rm --tty -i --restart='Never' --namespace default --image docker.io/bitnami/postgresql:11.6.0-debian-9-r0 --env="PGPASSWORD=$POSTGRES_PASSWORD" --command -- psql --host postgresql -U postgres -d postgres -p 5432

postgres=# \dt
List of relations
Schema | Name | Type  |  Owner
--------+------+-------+----------
public | todo | table | postgres
(1 row)

安装应用程序框架

• Prometheus提供度量，自动扩展和可观察性来测试系统的运行状况，使其能够通过提供度量以制定有关将比例缩放为零的决策来响应需求激增并削减成本。
• Linux虽然不是Kubernetes中运行工作负载的唯一选择，但它是标准且最易于使用的。
• 最初，OpenFaaS为开发人员提供了可移植的功能，但在部署API和微服务时效果很好。它的多功能性意味着可以部署和管理带有HTTP服务器的任何Docker容器。
• NATS是一个流行的CNCF项目，用于消息传递和发布/订阅。在PLONK堆栈中，它提供了异步执行请求和排队的功能。
• Kubernetes是我们在这里的原因。它提供了可伸缩的，自我修复的声明性基础结构。而且，如果您不再需要所有这些功能，则可以使用OpenFaaS简化其API。

arkade install openfaas

• 安装faas-cli。
• 获取密码。
• 重定向OpenFaaS网关UI（通过端口8080）
• 并通过命令行登录系统。

部署您的First Go API

faas-cli template store list | grep go
go                       openfaas           Classic Golang template
golang-http              openfaas-incubator Golang HTTP template
golang-middleware        openfaas-incubator Golang Middleware template

faas-cli template store pull golang-middleware

export PREFIX=alexellis2
export LANG=golang-middleware
export API_NAME=todo
faas-cli new --lang $LANG --prefix $PREFIX $API_NAME

• ./todo.yml -提供一种配置，部署和安装模板和名称的方法
• ./todo/handler.go -在这里您编写代码并添加所需的任何其他文件或软件包

package function
import (
   "net/http"
   "encoding/json"
)
type Todo struct {
   Description string `json:"description"`
}
func Handle(w http.ResponseWriter, r *http.Request) {
   todos := []Todo{}
   todos = append(todos, Todo{Description: "Run faas-cli up"})
   res, _ := json.Marshal(todos)
   w.WriteHeader(http.StatusOK)
   w.Header().Set("Content-Type", "application/json")
   w.Write([]byte(res))
}

gofmt -w -s ./todo/handler.go

Invoke your endpoint when ready:
curl http://127.0.0.1:8080/function/todo
{
"description": "Run faas-cli up"
}

允许用户创建新的TODO记录

import (
   "database/sql"
   _ "github.com/lib/pq"
...

var db *sql.DB

cd todo/
ls
handler.go
export GO111MODULE=on
go mod init

go get
go mod tidy
cat go.mod
module github.com/alexellis/todo1/todo
go 1.13
require github.com/lib/pq v1.3.0

cat go.mod > GO_REPLACE.txt

faas-cli build -f todo.yml --build-arg GO111MODULE=on

Step 16/29 : RUN go test ./... -cover
---> Running in 9a4017438500
go: downloading github.com/lib/pq v1.3.0
go: extracting github.com/lib/pq v1.3.0
go: finding github.com/lib/pq v1.3.0
?       github.com/alexellis/todo1/todo [no test files]
Removing intermediate container 9a4017438500

配置Postgresql访问的机密

// init       .   ,     ,   /   /

func init() {
       if _, err := os.Stat("/var/openfaas/secrets/password"); err == nil {
               password, _ := sdk.ReadSecret("password")
               user, _ := sdk.ReadSecret("username")
               host, _ := sdk.ReadSecret("host")
               dbName := os.Getenv("postgres_db")
               port := os.Getenv("postgres_port")
               sslmode := os.Getenv("postgres_sslmode")
               connStr := "postgres://" + user + ":" + password + "@" + host + ":" + port + "/" + dbName + "?sslmode=" + sslmode
var err error
               db, err = sql.Open("postgres", connStr)
               if err != nil {
                       panic(err.Error())
               }
               err = db.Ping()
               if err != nil {
                       panic(err.Error())
               }
       }
}

export POSTGRES_PASSWORD=$(kubectl get secret --namespace default postgresql -o jsonpath="{.data.postgresql-password}" | base64 --decode)
export USERNAME="postgres"
export PASSWORD=$POSTGRES_PASSWORD
export HOST="postgresql.default"
faas-cli secret create username --from-literal $USERNAME
faas-cli secret create password --from-literal $PASSWORD
faas-cli secret create host --from-literal $HOST

faas-cli secret ls
NAME
username
password
host
# And via kubectl:
kubectl get secret -n openfaas-fn
NAME                  TYPE                                  DATA   AGE
username              Opaque                                1      13s
password              Opaque                                1      13s
host                  Opaque                                1      12s

secrets:
   - host
   - password
   - username
   environment:
     postgres_db: postgres
     postgres_sslmode: "disable"
     postgres_port: 5432

cd todo
go get
go mod tidy
cd ..
faas-cli build -f todo.yml --build-arg GO111MODULE=on
Successfully built d2c609f8f559
Successfully tagged alexellis2/todo:latest
Image: alexellis2/todo:latest built.
[0] < Building todo done in 22.50s.
[0] Worker done.
Total build time: 22.50s

faas-cli logs todo
2020-03-26T14:10:03Z Forking - ./handler []
2020-03-26T14:10:03Z 2020/03/26 14:10:03 Started logging stderr from function.
2020-03-26T14:10:03Z 2020/03/26 14:10:03 Started logging stdout from function.
2020-03-26T14:10:03Z 2020/03/26 14:10:03 OperationalMode: http
2020-03-26T14:10:03Z 2020/03/26 14:10:03 Timeouts: read: 10s, write: 10s hard: 10s.
2020-03-26T14:10:03Z 2020/03/26 14:10:03 Listening on port: 8080
2020-03-26T14:10:03Z 2020/03/26 14:10:03 Metrics listening on port: 8081
2020-03-26T14:10:03Z 2020/03/26 14:10:03 Writing lock-file to: /tmp/.lock

echo | faas-cli invoke todo -f todo.yml
2020-03-26T14:11:02Z 2020/03/26 14:11:02 POST / - 200 OK - ContentLength: 35

err = db.Ping()
if err != nil {
   panic(err.Error())
}

编写插入代码

func insert(description string) error {
       res, err := db.Query(`insert into todo (id, description, created_date) values (DEFAULT, $1, now());`,
               description)
       if err != nil {
               return err
       }
       defer res.Close()
       return nil
}

func Handle(w http.ResponseWriter, r *http.Request) {
       if r.Method == http.MethodPost && r.URL.Path == "/create" {
               defer r.Body.Close()
               body, _ := ioutil.ReadAll(r.Body)
               if err := insert(string(body)); err != nil {
                       http.Error(w, fmt.Sprintf("unable to insert todo: %s", err.Error()), http.StatusInternalServerError)
               }
       }
}

echo | faas-cli invoke todo -f todo.yml
curl http://127.0.0.1:8080/function/todo/create --data "faas-cli build"
curl http://127.0.0.1:8080/function/todo/create --data "faas-cli push"
curl http://127.0.0.1:8080/function/todo/create --data "faas-cli deploy"

faas-cli logs todo
2020-03-26T14:35:29Z 2020/03/26 14:35:29 POST /create - 200 OK - ContentLength: 0

export POSTGRES_PASSWORD=$(kubectl get secret --namespace default postgresql -o jsonpath="{.data.postgresql-password}" | base64 --decode)
kubectl run postgresql-client --rm --tty -i --restart='Never' --namespace default --image docker.io/bitnami/postgresql:11.6.0-debian-9-r0 --env="PGPASSWORD=$POSTGRES_PASSWORD" --command -- psql --host postgresql -U postgres -d postgres -p 5432
postgres=# select * from todo;
id |   description   |        created_date        | completed_date
----+-----------------+----------------------------+----------------
1 | faas-cli build  | 2020-03-26 14:36:03.367789 |
2 | faas-cli push   | 2020-03-26 14:36:03.389656 |
3 | faas-cli deploy | 2020-03-26 14:36:03.797881 |

记录请求

func selectTodos() ([]Todo, error) {
   var error err
   var todos []Todo
   return todos, err
}

} else if r.Method == http.MethodGet && r.URL.Path == "/list" {
   todos, err := selectTodos()
   if err != nil {
       http.Error(w, fmt.Sprintf("unable to get todos: %s", err.Error()), http.StatusInternalServerError)
   }
   out, _ := json.Marshal(todos)
   w.Header().Set("Content-Type", "application/json")
   w.Write(out)
}

type Todo struct {
   ID int `json:"id"`
   Description   string `json:"description"`
   CreatedDate   *time.Time `json:"created_date"`
   CompletedDate *time.Time `json:"completed_date"`
}

func selectTodos() ([]Todo, error) {
       rows, getErr := db.Query(`select id, description, created_date, completed_date from todo;`)
   if getErr != nil {
       return []Todo{}, errors.Wrap(getErr, "unable to get from todo table")
   }
   todos := []Todo{}
   defer rows.Close()
   for rows.Next() {
       result := Todo{}
       scanErr := rows.Scan(&result.ID, &result.Description, &result.CreatedDate, &result.CompletedDate)
       if scanErr != nil {
           log.Println("scan err:", scanErr)
       }
       todos = append(todos, result)
   }
   return todos, nil
}

faas-cli up -f todo.yml --build-arg GO111MODULE=on
curl http://127.0.0.1:8080/function/todo/list

[
 {
   "id": 2,
   "description": "faas-cli build",
   "created_date": "2020-03-26T14:36:03.367789Z",
   "completed_date": null
 },
 {
   "id": 3,
   "description": "faas-cli push",
   "created_date": "2020-03-26T14:36:03.389656Z",
   "completed_date": null
 },
 {
   "id": 4,
   "description": "faas-cli deploy",
   "created_date": "2020-03-26T14:36:03.797881Z",
   "completed_date": null
 }
]

CompletedDate *time.Time `json:"completed_date,omitempty"`

总结完成的工作

• 已安装Go，Docker，kubectl和VSCode（IDE）
• 在我们的本地计算机上部署Kubernetes
• 使用arkade和helm3安装了Postgresql
• 为Kubernetes应用程序开发人员安装了OpenFaaS和PLONK堆栈
• 使用Go和golang-middlewareOpenFaaS模板创建了初始静态REST API
• 在我们的TODO API中添加了“插入”功能
• 向我们的TODO API添加了选择功能

• 使用静态承载令牌添加身份验证
• 使用静态HTML或React模板创建网页以呈现TODO列表并创建新元素。
• 向API添加多用户支持