Improve implementation around config (#1122)

* refactor config

* fix saas config

* feat(config): scanmodule for each server in config.toml

* feat(config): enable to specify containersOnly in config.toml

* add new keys of config.toml to discover.go

* fix summary output, logging

config/smtpconf.go

@@ -0,0 +1,65 @@
+package config
+
+import (
+	"github.com/asaskevich/govalidator"
+	"golang.org/x/xerrors"
+)
+
+// SMTPConf is smtp config
+type SMTPConf struct {
+	SMTPAddr      string   `toml:"smtpAddr,omitempty" json:"-"`
+	SMTPPort      string   `toml:"smtpPort,omitempty" valid:"port" json:"-"`
+	User          string   `toml:"user,omitempty" json:"-"`
+	Password      string   `toml:"password,omitempty" json:"-"`
+	From          string   `toml:"from,omitempty" json:"-"`
+	To            []string `toml:"to,omitempty" json:"-"`
+	Cc            []string `toml:"cc,omitempty" json:"-"`
+	SubjectPrefix string   `toml:"subjectPrefix,omitempty" json:"-"`
+}
+
+func checkEmails(emails []string) (errs []error) {
+	for _, addr := range emails {
+		if len(addr) == 0 {
+			return
+		}
+		if ok := govalidator.IsEmail(addr); !ok {
+			errs = append(errs, xerrors.Errorf("Invalid email address. email: %s", addr))
+		}
+	}
+	return
+}
+
+// Validate SMTP configuration
+func (c *SMTPConf) Validate() (errs []error) {
+	if !Conf.ToEmail {
+		return
+	}
+	// Check Emails fromat
+	emails := []string{}
+	emails = append(emails, c.From)
+	emails = append(emails, c.To...)
+	emails = append(emails, c.Cc...)
+
+	if emailErrs := checkEmails(emails); 0 < len(emailErrs) {
+		errs = append(errs, emailErrs...)
+	}
+
+	if len(c.SMTPAddr) == 0 {
+		errs = append(errs, xerrors.New("email.smtpAddr must not be empty"))
+	}
+	if len(c.SMTPPort) == 0 {
+		errs = append(errs, xerrors.New("email.smtpPort must not be empty"))
+	}
+	if len(c.To) == 0 {
+		errs = append(errs, xerrors.New("email.To required at least one address"))
+	}
+	if len(c.From) == 0 {
+		errs = append(errs, xerrors.New("email.From required at least one address"))
+	}
+
+	_, err := govalidator.ValidateStruct(c)
+	if err != nil {
+		errs = append(errs, err)
+	}
+	return
+}