70 lines
1.7 KiB
Go
70 lines
1.7 KiB
Go
// main is the composition root for the application.
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// It parses config, wires dependencies into an app struct, and delegates.
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// Implementation details lives in internal/; cmd/ should be kept thin by
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// deliberately operating only with high level concepts.
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package main
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import (
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"fmt"
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"os"
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"path/filepath"
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"gitea.djmil.dev/go/template/internal/greeter"
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"gitea.djmil.dev/go/template/pkg/logger"
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"gitea.djmil.dev/go/template/pkg/result"
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)
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// app holds all wired dependencies for the lifetime of the process.
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type app struct {
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cfg *Config
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log *logger.Logger
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greeter *greeter.Service
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}
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func newApp(cfg *Config) *app {
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var log *logger.Logger
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if cfg.App.Env == "dev" {
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log = logger.NewDevelopment()
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} else {
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log = logger.New(cfg.Logger.Level).Expect("create logger") // might fail dramatically
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}
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return &app{
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cfg: cfg,
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log: log,
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greeter: greeter.New(log),
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}
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}
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func main() {
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conf := parseArgs()
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app := newApp(conf)
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app.log.WithFields(map[string]any{
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"app": filepath.Base(os.Args[0]),
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"env": conf.App.Env,
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}).Info("starting up")
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if err := result.Run(app.run); err != nil {
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fmt.Fprintf(os.Stderr, "[failed] %v\n", err)
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if stack := result.StackTrace(err); stack != "" {
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fmt.Fprintf(os.Stderr, "%s\n", stack)
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}
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os.Exit(1)
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}
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}
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func (a *app) run() {
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// High level business logic goes here
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a.showGreeting(a.cfg.Greeter.Name)
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// Human readable messages.
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// Use logs for presenting technical data in machine friendly format.
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fmt.Printf("TODO: implement listening on port %d\n", a.cfg.App.Port)
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}
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func (a *app) showGreeting(name string) {
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msg := a.greeter.Greet(name).Expect("greeting")
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a.log.WithField("message", msg).Info("greeting complete")
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fmt.Println(msg)
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}
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