Praefect: Enable database replication queue by default

Thew PostgreSQL based implementation of the replication queue
is enabled by default.
In order to simplify unit testing the in-memory implementation
resides and can be used in case `memory_queue_enabled = true`
configuration option provided.

Closes: https://gitlab.com/gitlab-org/gitaly/-/issues/2615

6 files changed, 21 insertions, 15 deletions

diff --git a/changelogs/unreleased/ps-sql-queue-enabled.yml b/changelogs/unreleased/ps-sql-queue-enabled.yml
new file mode 100644
index 000000000..d61da8bb4
--- /dev/null
+++ b/changelogs/unreleased/ps-sql-queue-enabled.yml
@@ -0,0 +1,5 @@
+---
+title: 'Praefect: Enable database replication queue by default'
+merge_request: 2193
+author:
+type: changed
diff --git a/cmd/praefect/main.go b/cmd/praefect/main.go
index 7c42fb18a..322ae28b5 100644
--- a/cmd/praefect/main.go
+++ b/cmd/praefect/main.go
@@ -232,10 +232,10 @@ func run(cfgs []starter.Config, conf config.Config) error {
 	}
 
 	ds := datastore.Datastore{ReplicasDatastore: datastore.NewInMemory(conf)}
-	if conf.PostgresQueueEnabled {
-		ds.ReplicationEventQueue = datastore.NewPostgresReplicationEventQueue(db)
-	} else {
+	if conf.MemoryQueueEnabled {
 		ds.ReplicationEventQueue = datastore.NewMemoryReplicationEventQueue(conf)
+	} else {
+		ds.ReplicationEventQueue = datastore.NewPostgresReplicationEventQueue(db)
 	}
 
 	nodeManager, err := nodes.NewManager(logger, conf, db, ds, nodeLatencyHistogram)
diff --git a/internal/praefect/config/config.go b/internal/praefect/config/config.go
index 510eada28..adfd183dc 100644
--- a/internal/praefect/config/config.go
+++ b/internal/praefect/config/config.go
@@ -34,8 +34,8 @@ type Config struct {
 	DB                   `toml:"database"`
 	Failover             Failover `toml:"failover"`
 	// Keep for legacy reasons: remove after Omnibus has switched
-	FailoverEnabled      bool `toml:"failover_enabled"`
-	PostgresQueueEnabled bool `toml:"postgres_queue_enabled"`
+	FailoverEnabled    bool `toml:"failover_enabled"`
+	MemoryQueueEnabled bool `toml:"memory_queue_enabled"`
 }
 
 // VirtualStorage represents a set of nodes for a storage
@@ -145,7 +145,7 @@ func (c Config) Validate() error {
 
 // NeedsSQL returns true if the driver for SQL needs to be initialized
 func (c Config) NeedsSQL() bool {
-	return c.PostgresQueueEnabled || (c.Failover.Enabled && c.Failover.ElectionStrategy == "sql")
+	return !c.MemoryQueueEnabled || (c.Failover.Enabled && c.Failover.ElectionStrategy == "sql")
 }
 
 // DB holds Postgres client configuration data.
diff --git a/internal/praefect/config/config_test.go b/internal/praefect/config/config_test.go
index 0077e6094..c85894b08 100644
--- a/internal/praefect/config/config_test.go
+++ b/internal/praefect/config/config_test.go
@@ -257,7 +257,7 @@ func TestConfigParsing(t *testing.T) {
 					SSLKey:      "/path/to/key",
 					SSLRootCert: "/path/to/root-cert",
 				},
-				PostgresQueueEnabled: true,
+				MemoryQueueEnabled: true,
 			},
 		},
 	}
@@ -318,17 +318,17 @@ func TestNeedsSQL(t *testing.T) {
 		{
 			desc:     "default",
 			config:   Config{},
-			expected: false,
+			expected: true,
 		},
 		{
-			desc:     "PostgreSQL queue enabled",
-			config:   Config{PostgresQueueEnabled: true},
-			expected: true,
+			desc:     "Memory queue enabled",
+			config:   Config{MemoryQueueEnabled: true},
+			expected: false,
 		},
 		{
 			desc:     "Failover enabled with default election strategy",
 			config:   Config{Failover: Failover{Enabled: true}},
-			expected: false,
+			expected: true,
 		},
 		{
 			desc:     "Failover enabled with SQL election strategy",
@@ -337,12 +337,12 @@ func TestNeedsSQL(t *testing.T) {
 		},
 		{
 			desc:     "Both PostgresQL and SQL election strategy enabled",
-			config:   Config{PostgresQueueEnabled: true, Failover: Failover{Enabled: true, ElectionStrategy: "sql"}},
+			config:   Config{Failover: Failover{Enabled: true, ElectionStrategy: "sql"}},
 			expected: true,
 		},
 		{
 			desc:     "Both PostgresQL and SQL election strategy enabled but failover disabled",
-			config:   Config{PostgresQueueEnabled: true, Failover: Failover{Enabled: false, ElectionStrategy: "sql"}},
+			config:   Config{Failover: Failover{Enabled: false, ElectionStrategy: "sql"}},
 			expected: true,
 		},
 	}
diff --git a/internal/praefect/config/testdata/config.toml b/internal/praefect/config/testdata/config.toml
index c871972a4..a11918cb0 100644
--- a/internal/praefect/config/testdata/config.toml
+++ b/internal/praefect/config/testdata/config.toml
@@ -1,7 +1,7 @@
 listen_addr = ""
 socket_path = ""
 prometheus_listen_addr = ""
-postgres_queue_enabled = true
+memory_queue_enabled = true
 distributed_reads_enabled = true
 
 [logging]
diff --git a/internal/testhelper/testserver.go b/internal/testhelper/testserver.go
index 8d259c995..017e2dbc0 100644
--- a/internal/testhelper/testserver.go
+++ b/internal/testhelper/testserver.go
@@ -160,6 +160,7 @@ func (p *TestServer) Start() error {
 		Auth: auth.Config{
 			Token: p.token,
 		},
+		MemoryQueueEnabled: true,
 	}
 
 	for _, storage := range p.storages {