Prevent usage of other election strategies than per_repository

Praefect's legacy election strategies have been deprecated in 13.12
and are scheduled for removal in 14.0. This commit switches the
`per_repository` to be the default election strategy and ignores the
`failover.election_strategy` configuration key.

As there are still some tests in Gitaly's repo and in GitLab's repo
which are not configured to use the database, there's an additional
configuration key added which allows for still configuring the other
election strategies.

Changelog: removed

5 files changed, 10 insertions, 5 deletions

diff --git a/cmd/praefect/main.go b/cmd/praefect/main.go
index 3f8ee04d1..96c58bd3f 100644
--- a/cmd/praefect/main.go
+++ b/cmd/praefect/main.go
@@ -188,6 +188,10 @@ func initConfig() (config.Config, error) {
 		return config.Config{}, err
 	}
 
+	if !conf.AllowLegacyElectors {
+		conf.Failover.ElectionStrategy = config.ElectionStrategyPerRepository
+	}
+
 	if !conf.Failover.Enabled && conf.Failover.ElectionStrategy != "" {
 		logger.WithField("election_strategy", conf.Failover.ElectionStrategy).Warn(
 			"ignoring configured election strategy as failover is disabled")
diff --git a/config.praefect.toml.example b/config.praefect.toml.example
index 1afb7f890..afe0f9153 100644
--- a/config.praefect.toml.example
+++ b/config.praefect.toml.example
@@ -48,7 +48,6 @@ histogram_buckets = [0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10]
 
 [failover]
 enabled = true
-election_strategy = "sql" # Options: local, sql, per_repository. Defaults to 'sql'.
 
 [[virtual_storage]]
 name = 'praefect'
diff --git a/internal/praefect/config/config.go b/internal/praefect/config/config.go
index a82d35729..3acc17047 100644
--- a/internal/praefect/config/config.go
+++ b/internal/praefect/config/config.go
@@ -106,6 +106,7 @@ func DefaultReplicationConfig() Replication {
 
 // Config is a container for everything found in the TOML config file
 type Config struct {
+	AllowLegacyElectors  bool              `toml:"i_understand_my_election_strategy_is_unsupported_and_will_be_removed_without_warning"`
 	Reconciliation       Reconciliation    `toml:"reconciliation"`
 	Replication          Replication       `toml:"replication"`
 	ListenAddr           string            `toml:"listen_addr"`
@@ -149,7 +150,7 @@ func FromFile(filePath string) (Config, error) {
 		Reconciliation: DefaultReconciliationConfig(),
 		Replication:    DefaultReplicationConfig(),
 		// Sets the default Failover, to be overwritten when deserializing the TOML
-		Failover: Failover{Enabled: true, ElectionStrategy: ElectionStrategySQL},
+		Failover: Failover{Enabled: true, ElectionStrategy: ElectionStrategyPerRepository},
 	}
 	if err := toml.Unmarshal(b, conf); err != nil {
 		return Config{}, err
diff --git a/internal/praefect/config/config_test.go b/internal/praefect/config/config_test.go
index 9bcfe56fb..f8f803b07 100644
--- a/internal/praefect/config/config_test.go
+++ b/internal/praefect/config/config_test.go
@@ -295,7 +295,7 @@ func TestConfigParsing(t *testing.T) {
 				Replication: Replication{BatchSize: 1},
 				Failover: Failover{
 					Enabled:                  true,
-					ElectionStrategy:         ElectionStrategySQL,
+					ElectionStrategy:         ElectionStrategyPerRepository,
 					ErrorThresholdWindow:     config.Duration(20 * time.Second),
 					WriteErrorThresholdCount: 1500,
 					ReadErrorThresholdCount:  100,
@@ -331,7 +331,7 @@ func TestConfigParsing(t *testing.T) {
 				Replication:         DefaultReplicationConfig(),
 				Failover: Failover{
 					Enabled:           true,
-					ElectionStrategy:  ElectionStrategySQL,
+					ElectionStrategy:  ElectionStrategyPerRepository,
 					BootstrapInterval: config.Duration(time.Second),
 					MonitorInterval:   config.Duration(3 * time.Second),
 				},
diff --git a/internal/testhelper/testserver/gitaly.go b/internal/testhelper/testserver/gitaly.go
index 0735636d0..90d74a620 100644
--- a/internal/testhelper/testserver/gitaly.go
+++ b/internal/testhelper/testserver/gitaly.go
@@ -59,7 +59,8 @@ func runPraefectProxy(t testing.TB, cfg config.Cfg, gitalyAddr, praefectBinPath
 	praefectServerSocketPath := "unix://" + testhelper.GetTemporaryGitalySocketFileName(t)
 
 	conf := praefectconfig.Config{
-		SocketPath: praefectServerSocketPath,
+		AllowLegacyElectors: true,
+		SocketPath:          praefectServerSocketPath,
 		Auth: auth.Config{
 			Token: cfg.Auth.Token,
 		},