Initial commit

config.go

@@ -0,0 +1,82 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+
+	goutils "github.com/jkaninda/go-utils"
+)
+
+// Config is the runtime configuration, read entirely from environment
+// variables — the twelve-factor way, and exactly how Miabi injects settings
+// into a deployed application (Postgres connection details land here when you
+// attach a managed database to the app).
+type Config struct {
+	Port        int
+	DBDriver    string // "postgres" or "sqlite"
+	DatabaseDSN string
+	AppName     string
+	Version     string
+	Seed        bool
+}
+
+// LoadConfig builds the Config from the environment.
+func LoadConfig() (Config, error) {
+	driver, dsn := resolveDatabase()
+	return Config{
+		Port:        goutils.EnvInt("PORT", 8080),
+		AppName:     goutils.Env("APP_NAME", "Miabi Guestbook"),
+		Version:     resolveVersion(),
+		Seed:        goutils.Env("SEED", "true") == "true",
+		DBDriver:    driver,
+		DatabaseDSN: dsn,
+	}, nil
+}
+
+// resolveDatabase picks the database driver and DSN.
+//
+// The driver comes from DB_DRIVER (postgres|sqlite). When DB_DRIVER is unset it
+// is inferred: if Postgres is configured (DATABASE_URL or DB_HOST is present)
+// Postgres is used; otherwise the app falls back to a zero-config SQLite file —
+// handy for local dev and demos with nothing else to set up. On Miabi, attach a
+// managed Postgres and it is selected automatically.
+func resolveDatabase() (driver, dsn string) {
+	driver = strings.ToLower(goutils.Env("DB_DRIVER", ""))
+	if driver == "" {
+		if goutils.Env("DATABASE_URL", "") != "" || goutils.Env("DB_HOST", "") != "" {
+			driver = "postgres"
+		} else {
+			driver = "sqlite"
+		}
+	}
+
+	switch driver {
+	case "sqlite", "sqlite3":
+		// A file path; use ":memory:" for an ephemeral in-memory database. The
+		// parent directory is created on startup. In the container this defaults
+		// to /data (a volume); see DB_PATH in the Dockerfile.
+		return "sqlite", goutils.Env("DB_PATH", "data/guestbook.db")
+	default:
+		return "postgres", postgresDSN()
+	}
+}
+
+// postgresDSN resolves the Postgres connection, following Miabi's convention:
+//
+//   - DATABASE_URL — a full DSN (URL or key=value). Preferred, and what Miabi's
+//     managed databases inject. When set, it is used verbatim.
+//   - Discrete DB_* variables — assembled into a key=value DSN otherwise.
+func postgresDSN() string {
+	if url := goutils.Env("DATABASE_URL", ""); url != "" {
+		return url
+	}
+	return fmt.Sprintf(
+		"host=%s user=%s password=%s dbname=%s port=%d sslmode=%s",
+		goutils.Env("DB_HOST", "localhost"),
+		goutils.Env("DB_USER", "postgres"),
+		goutils.Env("DB_PASSWORD", "postgres"),
+		goutils.Env("DB_NAME", "guestbook"),
+		goutils.EnvInt("DB_PORT", 5432),
+		goutils.Env("DB_SSL_MODE", "disable"),
+	)
+}