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/slackconf.go

@@ -0,0 +1,51 @@
+package config
+
+import (
+	"strings"
+
+	"github.com/asaskevich/govalidator"
+	"golang.org/x/xerrors"
+)
+
+// SlackConf is slack config
+type SlackConf struct {
+	HookURL     string   `valid:"url" json:"-" toml:"hookURL,omitempty"`
+	LegacyToken string   `json:"-" toml:"legacyToken,omitempty"`
+	Channel     string   `json:"-" toml:"channel,omitempty"`
+	IconEmoji   string   `json:"-" toml:"iconEmoji,omitempty"`
+	AuthUser    string   `json:"-" toml:"authUser,omitempty"`
+	NotifyUsers []string `toml:"notifyUsers,omitempty" json:"-"`
+	Text        string   `json:"-"`
+}
+
+// Validate validates configuration
+func (c *SlackConf) Validate() (errs []error) {
+	if !Conf.ToSlack {
+		return
+	}
+
+	if len(c.HookURL) == 0 && len(c.LegacyToken) == 0 {
+		errs = append(errs, xerrors.New("slack.hookURL or slack.LegacyToken must not be empty"))
+	}
+
+	if len(c.Channel) == 0 {
+		errs = append(errs, xerrors.New("slack.channel must not be empty"))
+	} else {
+		if !(strings.HasPrefix(c.Channel, "#") ||
+			c.Channel == "${servername}") {
+			errs = append(errs, xerrors.Errorf(
+				"channel's prefix must be '#', channel: %s", c.Channel))
+		}
+	}
+
+	if len(c.AuthUser) == 0 {
+		errs = append(errs, xerrors.New("slack.authUser must not be empty"))
+	}
+
+	_, err := govalidator.ValidateStruct(c)
+	if err != nil {
+		errs = append(errs, err)
+	}
+
+	return
+}