Go для DevOps: CLI-инструменты

1package main
2
3import (
4    "flag"
5    "fmt"
6    "os"
7)
8
9func main() {
10    // Определение флагов
11    name := flag.String("name", "World", "Name to greet")
12    count := flag.Int("count", 1, "Number of greetings")
13    verbose := flag.Bool("verbose", false, "Verbose output")
14
15    // Парсинг
16    flag.Parse()
17
18    if *verbose {
19        fmt.Println("Starting program...")
20    }
21
22    for i := 0; i < *count; i++ {
23        fmt.Printf("Hello, %s!\n", *name)
24    }
25}

1func main() {
2    // Основные команды
3    if len(os.Args) < 2 {
4        fmt.Println("Usage: mytool <command>")
5        os.Exit(1)
6    }
7
8    switch os.Args[1] {
9    case "serve":
10        serveCmd()
11    case "migrate":
12        migrateCmd()
13    case "version":
14        fmt.Println("v1.0.0")
15    default:
16        fmt.Printf("Unknown command: %s\n", os.Args[1])
17        os.Exit(1)
18    }
19}

1go get github.com/spf13/cobra

1cobra init myapp
2cd myapp
3cobra add serve
4cobra add migrate

1// cmd/root.go
2package cmd
3
4import (
5    "fmt"
6    "os"
7    "github.com/spf13/cobra"
8)
9
10var rootCmd = &cobra.Command{
11    Use:   "myapp",
12    Short: "My awesome CLI tool",
13    Long:  "A longer description of your CLI tool",
14}
15
16func Execute() {
17    if err := rootCmd.Execute(); err != nil {
18        fmt.Println(err)
19        os.Exit(1)
20    }
21}
22
23func init() {
24    rootCmd.PersistentFlags().StringVarP(&configFile, "config", "c", "", "config file")
25    rootCmd.PersistentFlags().BoolVarP(&verbose, "verbose", "v", false, "verbose output")
26}

1// cmd/serve.go
2package cmd
3
4import (
5    "fmt"
6    "github.com/spf13/cobra"
7)
8
9var serveCmd = &cobra.Command{
10    Use:   "serve",
11    Short: "Start the server",
12    RunE: func(cmd *cobra.Command, args []string) error {
13        port, _ := cmd.Flags().GetInt("port")
14        fmt.Printf("Starting server on port %d\n", port)
15        return nil
16    },
17}
18
19func init() {
20    serveCmd.Flags().IntP("port", "p", 8080, "Port to listen on")
21    rootCmd.AddCommand(serveCmd)
22}

1package main
2
3import (
4    "fmt"
5    "github.com/spf13/viper"
6)
7
8func main() {
9    viper.SetConfigName("config")
10    viper.SetConfigType("yaml")
11    viper.AddConfigPath(".")
12    viper.AddConfigPath("$HOME/.myapp")
13
14    // Значения по умолчанию
15    viper.SetDefault("server.port", 8080)
16    viper.SetDefault("server.host", "localhost")
17
18    // Переменные окружения
19    viper.SetEnvPrefix("MYAPP")
20    viper.AutomaticEnv()
21
22    // Чтение конфига
23    if err := viper.ReadInConfig(); err != nil {
24        fmt.Printf("Config error: %v\n", err)
25    }
26
27    // Получение значений
28    port := viper.GetInt("server.port")
29    host := viper.GetString("server.host")
30    fmt.Printf("Server: %s:%d\n", host, port)
31}

1server:
2  host: localhost
3  port: 8080
4
5database:
6  host: localhost
7  port: 5432
8  name: mydb

1BINARY_NAME=myapp
2VERSION=$(shell git describe --tags --always)
3
4build-linux:
5    GOOS=linux GOARCH=amd64 go build -o $(BINARY_NAME)-linux-amd64 .
6
7build-darwin:
8    GOOS=darwin GOARCH=arm64 go build -o $(BINARY_NAME)-darwin-arm64 .
9
10build-windows:
11    GOOS=windows GOARCH=amd64 go build -o $(BINARY_NAME)-windows-amd64.exe .
12
13build-all: build-linux build-darwin build-windows
14
15clean:
16    rm -f $(BINARY_NAME)-*

1# .goreleaser.yml
2builds:
3  - binary: myapp
4    goos:
5      - linux
6      - darwin
7      - windows
8    goarch:
9      - amd64
10      - arm64
11
12archives:
13  - format: tar.gz
14    format_overrides:
15      - goos: windows
16        format: zip
17
18checksum:
19  name_template: 'checksums.txt'
20
21snapshot:
22  name_template: "{{ .Tag }}-next"

1package main
2
3import (
4    "log/slog"
5    "os"
6)
7
8func main() {
9    logger := slog.New(slog.NewJSONHandler(os.Stdout, nil))
10    slog.SetDefault(logger)
11
12    slog.Info("server started",
13        "port", 8080,
14        "host", "localhost",
15    )
16
17    slog.Error("failed to connect",
18        "error", err,
19        "host", dbHost,
20    )
21}

1myapp/
2├── cmd/
3│   ├── root.go
4│   ├── serve.go
5│   └── migrate.go
6├── internal/
7│   ├── server/
8│   └── db/
9├── config/
10│   └── config.yaml
11├── main.go
12├── go.mod
13└── Makefile

1func TestServeCommand(t *testing.T) {
2    cmd := rootCmd
3    cmd.SetArgs([]string{"serve", "--port", "9090"})
4
5    buf := new(bytes.Buffer)
6    cmd.SetOut(buf)
7
8    err := cmd.Execute()
9    if err != nil {
10        t.Fatalf("unexpected error: %v", err)
11    }
12
13    if !strings.Contains(buf.String(), "9090") {
14        t.Errorf("expected port 9090 in output")
15    }
16}