Configuration transposed into environment variables (#82)

Configuration file not required anymore
DIUN_DB env var renamed DIUN_DB_PATH
Only accept duration as timeout value (10 becomes 10s)
Add getting started doc
Enhanced documentation
Add note about test notifications (#79)
Improve configuration management
Fix telegram init
All fields in configuration now camelCased
Improve configuration validation
Update doc
Update FAQ

Co-authored-by: CrazyMax <crazy-max@users.noreply.github.com>

internal/config/config.go

@@ -3,92 +3,91 @@ package config
 import (
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"os"
-	"path"
 
 	"github.com/crazy-max/diun/v3/internal/model"
-	"github.com/crazy-max/diun/v3/pkg/utl"
+	"github.com/crazy-max/diun/v3/third_party/traefik/config/env"
+	"github.com/crazy-max/diun/v3/third_party/traefik/config/file"
+	"github.com/go-playground/validator/v10"
 	"github.com/pkg/errors"
-	"gopkg.in/yaml.v2"
 )
 
 // Config holds configuration details
 type Config struct {
-	Cli       model.Cli
-	App       model.App
-	Db        model.Db                 `yaml:"db,omitempty"`
-	Watch     model.Watch              `yaml:"watch,omitempty"`
-	Notif     *model.Notif             `yaml:"notif,omitempty"`
-	RegOpts   map[string]model.RegOpts `yaml:"regopts,omitempty"`
-	Providers *model.Providers         `yaml:"providers,omitempty"`
+	Db        *model.Db                 `yaml:"db,omitempty" json:"db,omitempty"`
+	Watch     *model.Watch              `yaml:"watch,omitempty" json:"watch,omitempty"`
+	Notif     *model.Notif              `yaml:"notif,omitempty" json:"notif,omitempty"`
+	RegOpts   map[string]*model.RegOpts `yaml:"regopts,omitempty" json:"regopts,omitempty" validate:"unique"`
+	Providers *model.Providers          `yaml:"providers,omitempty" json:"providers,omitempty" validate:"required"`
 }
 
 // Load returns Configuration struct
-func Load(cli model.Cli, version string) (*Config, error) {
-	var err error
-	var cfg = Config{
-		Cli: cli,
-		App: model.App{
-			ID:      "diun",
-			Name:    "Diun",
-			Desc:    "Docker image update notifier",
-			URL:     "https://github.com/crazy-max/diun",
-			Author:  "CrazyMax",
-			Version: version,
-		},
-		Db: model.Db{
-			Path: "diun.db",
-		},
-		Watch: model.Watch{
-			Workers:         10,
-			Schedule:        "0 * * * *",
-			FirstCheckNotif: utl.NewFalse(),
-		},
+func Load(cfgfile string) (*Config, error) {
+	cfg := Config{
+		Db:    (&model.Db{}).GetDefaults(),
+		Watch: (&model.Watch{}).GetDefaults(),
 	}
 
-	if _, err = os.Lstat(cli.Cfgfile); err != nil {
-		return nil, fmt.Errorf("unable to open config file, %s", err)
+	if err := cfg.loadFile(cfgfile, &cfg); err != nil {
+		return nil, err
 	}
 
-	bytes, err := ioutil.ReadFile(cli.Cfgfile)
-	if err != nil {
-		return nil, fmt.Errorf("unable to read config file, %s", err)
+	if err := cfg.loadEnv(&cfg); err != nil {
+		return nil, err
 	}
 
-	if err := yaml.UnmarshalStrict(bytes, &cfg); err != nil {
-		return nil, fmt.Errorf("unable to decode into struct, %v", err)
-	}
-
-	if err := cfg.validate(); err != nil {
+	validate := validator.New()
+	if err := validate.Struct(&cfg); err != nil {
 		return nil, err
 	}
 
 	return &cfg, nil
 }
 
-func (cfg *Config) validate() error {
-	cfg.Db.Path = utl.GetEnv("DIUN_DB", cfg.Db.Path)
-	if cfg.Db.Path == "" {
-		return errors.New("database path is required")
+func (cfg *Config) loadFile(cfgfile string, out interface{}) error {
+	if len(cfgfile) == 0 {
+		return nil
 	}
-	cfg.Db.Path = path.Clean(cfg.Db.Path)
 
-	if err := cfg.validateNotif(); err != nil {
-		return err
+	if _, err := os.Lstat(cfgfile); os.IsNotExist(err) {
+		return fmt.Errorf("config file %s not found", cfgfile)
 	}
-	if err := cfg.validateRegopts(); err != nil {
-		return err
-	}
-	if err := cfg.validateProviders(); err != nil {
-		return err
+
+	if err := file.Decode(cfgfile, out); err != nil {
+		return errors.Wrap(err, "failed to decode configuration from file")
 	}
 
 	return nil
 }
 
-// Display configuration in a pretty JSON format
-func (cfg *Config) Display() string {
+func (cfg *Config) loadEnv(out interface{}) error {
+	var envvars []string
+	for _, envvar := range env.FindPrefixedEnvVars(os.Environ(), "DIUN_", out) {
+		envvars = append(envvars, envvar)
+	}
+	if len(envvars) == 0 {
+		return nil
+	}
+
+	if err := env.Decode(envvars, "DIUN_", out); err != nil {
+		return errors.Wrap(err, "failed to decode configuration from environment variables")
+	}
+
+	return nil
+}
+
+func (cfg *Config) GetRegOpts(id string) (*model.RegOpts, error) {
+	if len(id) == 0 {
+		return (&model.RegOpts{}).GetDefaults(), nil
+	}
+	if regopts, ok := cfg.RegOpts[id]; ok {
+		return regopts, nil
+	}
+	return (&model.RegOpts{}).GetDefaults(), fmt.Errorf("%s not found", id)
+}
+
+// String returns the string representation of configuration
+func (cfg *Config) String() string {
 	b, _ := json.MarshalIndent(cfg, "", "  ")
 	return string(b)
 }