[feature] make account sign-up / backlog limits configurable (#3768)

4 files changed, 92 insertions, 29 deletions

diff --git a/internal/config/config.go b/internal/config/config.go
index 5c59c47cc..33003d0f9 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -92,10 +92,12 @@ type Configuration struct {
 	InstanceSubscriptionsProcessEvery time.Duration      `name:"instance-subscriptions-process-every" usage:"Period to elapse between instance subscriptions processing jobs, starting from instance-subscriptions-process-from."`
 	InstanceStatsMode                 string             `name:"instance-stats-mode" usage:"Allows you to customize the way stats are served to crawlers: one of '', 'serve', 'zero', 'baffle'. Home page stats remain unchanged."`
 
-	AccountsRegistrationOpen bool `name:"accounts-registration-open" usage:"Allow anyone to submit an account signup request. If false, server will be invite-only."`
-	AccountsReasonRequired   bool `name:"accounts-reason-required" usage:"Do new account signups require a reason to be submitted on registration?"`
-	AccountsAllowCustomCSS   bool `name:"accounts-allow-custom-css" usage:"Allow accounts to enable custom CSS for their profile pages and statuses."`
-	AccountsCustomCSSLength  int  `name:"accounts-custom-css-length" usage:"Maximum permitted length (characters) of custom CSS for accounts."`
+	AccountsRegistrationOpen         bool `name:"accounts-registration-open" usage:"Allow anyone to submit an account signup request. If false, server will be invite-only."`
+	AccountsReasonRequired           bool `name:"accounts-reason-required" usage:"Do new account signups require a reason to be submitted on registration?"`
+	AccountsRegistrationDailyLimit   int  `name:"accounts-registration-daily-limit" usage:"Limit amount of approved account sign-ups allowed per 24hrs before registration is closed. 0 or less = no limit."`
+	AccountsRegistrationBacklogLimit int  `name:"accounts-registration-backlog-limit" usage:"Limit how big the 'accounts pending approval' queue can grow before registration is closed. 0 or less = no limit."`
+	AccountsAllowCustomCSS           bool `name:"accounts-allow-custom-css" usage:"Allow accounts to enable custom CSS for their profile pages and statuses."`
+	AccountsCustomCSSLength          int  `name:"accounts-custom-css-length" usage:"Maximum permitted length (characters) of custom CSS for accounts."`
 
 	MediaDescriptionMinChars int           `name:"media-description-min-chars" usage:"Min required chars for an image description"`
 	MediaDescriptionMaxChars int           `name:"media-description-max-chars" usage:"Max permitted chars for an image description"`
diff --git a/internal/config/defaults.go b/internal/config/defaults.go
index 157dfde0a..7f66e4209 100644
--- a/internal/config/defaults.go
+++ b/internal/config/defaults.go
@@ -68,10 +68,12 @@ var Defaults = Configuration{
 	InstanceSubscriptionsProcessFrom:  "23:00",        // 11pm,
 	InstanceSubscriptionsProcessEvery: 24 * time.Hour, // 1/day.
 
-	AccountsRegistrationOpen: false,
-	AccountsReasonRequired:   true,
-	AccountsAllowCustomCSS:   false,
-	AccountsCustomCSSLength:  10000,
+	AccountsRegistrationOpen:         false,
+	AccountsReasonRequired:           true,
+	AccountsRegistrationDailyLimit:   10,
+	AccountsRegistrationBacklogLimit: 20,
+	AccountsAllowCustomCSS:           false,
+	AccountsCustomCSSLength:          10000,
 
 	MediaDescriptionMinChars: 0,
 	MediaDescriptionMaxChars: 1500,
diff --git a/internal/config/helpers.gen.go b/internal/config/helpers.gen.go
index 54d1b62d9..d3ccf16ea 100644
--- a/internal/config/helpers.gen.go
+++ b/internal/config/helpers.gen.go
@@ -1132,6 +1132,56 @@ func GetAccountsReasonRequired() bool { return global.GetAccountsReasonRequired(
 // SetAccountsReasonRequired safely sets the value for global configuration 'AccountsReasonRequired' field
 func SetAccountsReasonRequired(v bool) { global.SetAccountsReasonRequired(v) }
 
+// GetAccountsRegistrationDailyLimit safely fetches the Configuration value for state's 'AccountsRegistrationDailyLimit' field
+func (st *ConfigState) GetAccountsRegistrationDailyLimit() (v int) {
+	st.mutex.RLock()
+	v = st.config.AccountsRegistrationDailyLimit
+	st.mutex.RUnlock()
+	return
+}
+
+// SetAccountsRegistrationDailyLimit safely sets the Configuration value for state's 'AccountsRegistrationDailyLimit' field
+func (st *ConfigState) SetAccountsRegistrationDailyLimit(v int) {
+	st.mutex.Lock()
+	defer st.mutex.Unlock()
+	st.config.AccountsRegistrationDailyLimit = v
+	st.reloadToViper()
+}
+
+// AccountsRegistrationDailyLimitFlag returns the flag name for the 'AccountsRegistrationDailyLimit' field
+func AccountsRegistrationDailyLimitFlag() string { return "accounts-registration-daily-limit" }
+
+// GetAccountsRegistrationDailyLimit safely fetches the value for global configuration 'AccountsRegistrationDailyLimit' field
+func GetAccountsRegistrationDailyLimit() int { return global.GetAccountsRegistrationDailyLimit() }
+
+// SetAccountsRegistrationDailyLimit safely sets the value for global configuration 'AccountsRegistrationDailyLimit' field
+func SetAccountsRegistrationDailyLimit(v int) { global.SetAccountsRegistrationDailyLimit(v) }
+
+// GetAccountsRegistrationBacklogLimit safely fetches the Configuration value for state's 'AccountsRegistrationBacklogLimit' field
+func (st *ConfigState) GetAccountsRegistrationBacklogLimit() (v int) {
+	st.mutex.RLock()
+	v = st.config.AccountsRegistrationBacklogLimit
+	st.mutex.RUnlock()
+	return
+}
+
+// SetAccountsRegistrationBacklogLimit safely sets the Configuration value for state's 'AccountsRegistrationBacklogLimit' field
+func (st *ConfigState) SetAccountsRegistrationBacklogLimit(v int) {
+	st.mutex.Lock()
+	defer st.mutex.Unlock()
+	st.config.AccountsRegistrationBacklogLimit = v
+	st.reloadToViper()
+}
+
+// AccountsRegistrationBacklogLimitFlag returns the flag name for the 'AccountsRegistrationBacklogLimit' field
+func AccountsRegistrationBacklogLimitFlag() string { return "accounts-registration-backlog-limit" }
+
+// GetAccountsRegistrationBacklogLimit safely fetches the value for global configuration 'AccountsRegistrationBacklogLimit' field
+func GetAccountsRegistrationBacklogLimit() int { return global.GetAccountsRegistrationBacklogLimit() }
+
+// SetAccountsRegistrationBacklogLimit safely sets the value for global configuration 'AccountsRegistrationBacklogLimit' field
+func SetAccountsRegistrationBacklogLimit(v int) { global.SetAccountsRegistrationBacklogLimit(v) }
+
 // GetAccountsAllowCustomCSS safely fetches the Configuration value for state's 'AccountsAllowCustomCSS' field
 func (st *ConfigState) GetAccountsAllowCustomCSS() (v bool) {
 	st.mutex.RLock()
diff --git a/internal/processing/user/create.go b/internal/processing/user/create.go
index 0d848583e..f878d8320 100644
--- a/internal/processing/user/create.go
+++ b/internal/processing/user/create.go
@@ -44,34 +44,43 @@ func (p *Processor) Create(
 	app *gtsmodel.Application,
 	form *apimodel.AccountCreateRequest,
 ) (*gtsmodel.User, gtserror.WithCode) {
-	const (
-		usersPerDay = 10
-		regBacklog  = 20
+	var (
+		usersPerDay = config.GetAccountsRegistrationDailyLimit()
+		regBacklog  = config.GetAccountsRegistrationBacklogLimit()
 	)
 
-	// Ensure no more than usersPerDay
+	// If usersPerDay limit is in place,
+	// ensure no more than usersPerDay
 	// have registered in the last 24h.
-	newUsersCount, err := p.state.DB.CountApprovedSignupsSince(ctx, time.Now().Add(-24*time.Hour))
-	if err != nil {
-		err := fmt.Errorf("db error counting new users: %w", err)
-		return nil, gtserror.NewErrorInternalError(err)
-	}
+	if usersPerDay > 0 {
+		newUsersCount, err := p.state.DB.CountApprovedSignupsSince(ctx, time.Now().Add(-24*time.Hour))
+		if err != nil {
+			err := fmt.Errorf("db error counting new users: %w", err)
+			return nil, gtserror.NewErrorInternalError(err)
+		}
 
-	if newUsersCount >= usersPerDay {
-		err := fmt.Errorf("this instance has hit its limit of new sign-ups for today; you can try again tomorrow")
-		return nil, gtserror.NewErrorUnprocessableEntity(err, err.Error())
+		if newUsersCount >= usersPerDay {
+			err := fmt.Errorf("this instance has hit its limit of new sign-ups for today (%d); you can try again tomorrow", usersPerDay)
+			return nil, gtserror.NewErrorUnprocessableEntity(err, err.Error())
+		}
 	}
 
-	// Ensure the new users backlog isn't full.
-	backlogLen, err := p.state.DB.CountUnhandledSignups(ctx)
-	if err != nil {
-		err := fmt.Errorf("db error counting registration backlog length: %w", err)
-		return nil, gtserror.NewErrorInternalError(err)
-	}
+	// If registration backlog limit is
+	// in place, ensure backlog isn't full.
+	if regBacklog > 0 {
+		backlogLen, err := p.state.DB.CountUnhandledSignups(ctx)
+		if err != nil {
+			err := fmt.Errorf("db error counting registration backlog length: %w", err)
+			return nil, gtserror.NewErrorInternalError(err)
+		}
 
-	if backlogLen >= regBacklog {
-		err := fmt.Errorf("this instance's sign-up backlog is currently full; you must wait until pending sign-ups are handled by the admin(s)")
-		return nil, gtserror.NewErrorUnprocessableEntity(err, err.Error())
+		if backlogLen >= regBacklog {
+			err := fmt.Errorf(
+				"this instance's sign-up backlog is currently full (%d sign-ups pending approval); "+
+					"you must wait until some pending sign-ups are handled by the admin(s)", regBacklog,
+			)
+			return nil, gtserror.NewErrorUnprocessableEntity(err, err.Error())
+		}
 	}
 
 	emailAvailable, err := p.state.DB.IsEmailAvailable(ctx, form.Email)