djmil
4f55fcbef5
- store build metadata (version, commit, date) - multi-binary build: `make build` builds all packages from ./cmd - devcontainer adds ./bin to the PATH by default
86 lines
2.3 KiB
Go
86 lines
2.3 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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"io"
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"os"
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"path/filepath"
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"gitea.djmil.dev/go/template/internal/buildinfo"
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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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// Open the debug writer if requested. The OS closes it on exit.
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var debugOut io.Writer
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if cfg.Logger.LogDump != "" {
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debugOut = result.Of(os.Create(cfg.Logger.LogDump)).Expect("enable logs dump") // #nosec G304 — CLI flag
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}
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log := logger.NewCLI(cfg.Logger.Level, debugOut).Expect("create logger")
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log.Debug("config", "port", cfg.App.Port, "level", cfg.Logger.Level, "env", cfg.App.Env)
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if cfg.App.Env == "dev" {
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log.Warn("dev mode — not for production")
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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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if conf.Version {
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fmt.Println(buildinfo.String())
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return
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}
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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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// Warm up the greeter with a few names before the real call.
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// In debug mode this produces repeated identical debug lines from the greeter,
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// demonstrating how the deduplication counter collapses them in-place.
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for _, name := range []string{"Alice", "Bob", "Carol", "Dave"} {
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a.greeter.Greet(name)
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}
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a.showGreeting(a.cfg.Greeter.Name)
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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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