[licensor]: introduce concept of a fallback license with limited features

Author: Simon Emms

components/licensor/ee/pkg/licensor/licensor.go

@@ -117,9 +117,18 @@ func (lvl LicenseLevel) allowance() allowance {
 	return a
 }
 
+// Fallback license is used when the instance exceeds the number of licenses - it allows limited access
+var fallbackLicense = LicensePayload{
+	ID:    "fallback-license",
+	Level: LevelTeam,
+	Seats: 0,
+	// Domain, ValidUntil are free for all
+}
+
+// Default license is used when no valid license is given - it allows full access up to 10 users
 var defaultLicense = LicensePayload{
 	ID:    "default-license",
-	Level: LevelTeam,
+	Level: LevelEnterprise,
 	Seats: 10,
 	// Domain, ValidUntil are free for all
 }
@@ -163,7 +172,15 @@ func (e *Evaluator) Enabled(feature Feature, seats int) bool {
 		return false
 	}
 
-	_, ok := e.lic.Level.allowance().Features[feature]
+	var ok bool
+	if e.lic.Seats == 0 || seats <= e.lic.Seats {
+		// License has enough seats available - evaluate this license
+		_, ok = e.lic.Level.allowance().Features[feature]
+	} else {
+		// License has run out of seats - use the fallback license
+		_, ok = fallbackLicense.Level.allowance().Features[feature]
+	}
+
 	return ok
 }