Default to using SQLite as the garage metadata db engine

go/cmd/entrypoint/daemon.go

@@ -86,6 +86,8 @@ var subCmdDaemon = subCmd{
 			}()
 		}
 
+		ctx.logger.Info(ctx, "Daemon successfully started up")
+
 		<-ctx.Done()
 		return nil
 	},

go/daemon/children/garage.go

@@ -91,6 +91,11 @@ func garageWriteChildConfig(
 		)
 	)
 
+	dbEngine, err := garagesrv.GetDBEngine(alloc.MetaPath)
+	if err != nil {
+		return "", false, fmt.Errorf("getting alloc db engine: %w", err)
+	}
+
 	changed, err := garagesrv.WriteGarageTomlFile(
 		ctx,
 		logger,
@@ -101,6 +106,7 @@ func garageWriteChildConfig(
 
 			RPCSecret:  rpcSecret,
 			AdminToken: adminToken,
+			DBEngine:   dbEngine,
 
 			LocalNode:      node,
 			BootstrapPeers: hostBootstrap.GarageNodes(),

go/daemon/network/network_it_test.go

@@ -4,11 +4,15 @@ import (
 	"isle/bootstrap"
 	"isle/daemon/daecommon"
 	"isle/garage"
+	"isle/garage/garagesrv"
 	"isle/jsonutil"
 	"isle/nebula"
+	"os"
+	"path/filepath"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestCreate(t *testing.T) {
@@ -136,7 +140,7 @@ func TestNetwork_SetConfig(t *testing.T) {
 		return roles
 	}
 
-	t.Run("add storage alloc", func(t *testing.T) {
+	t.Run("add storage alloc/simple", func(t *testing.T) {
 		var (
 			h             = newIntegrationHarness(t)
 			network       = h.createNetwork(t, "primus", nil)
@@ -185,6 +189,55 @@ func TestNetwork_SetConfig(t *testing.T) {
 		layout, err := network.garageAdminClient(t).GetLayout(h.ctx)
 		assert.NoError(t, err)
 		assert.ElementsMatch(t, expRoles, layout.Roles)
+
+		t.Log("Checking that garage is using the expected db engine")
+		garageConfig, err := os.ReadFile(
+			filepath.Join(network.runtimeDir.Path, "garage-4901.toml"),
+		)
+		assert.NoError(t, err)
+		assert.Contains(t,
+			string(garageConfig),
+			`db_engine = "`+garagesrv.DBEngineSqlite+`"`,
+		)
+	})
+
+	t.Run("add storage alloc/lmdb", func(t *testing.T) {
+		var (
+			h             = newIntegrationHarness(t)
+			network       = h.createNetwork(t, "primus", nil)
+			networkConfig = network.getConfig(t)
+			dataPath      = h.mkDir(t, "data").Path
+			metaPath      = h.mkDir(t, "meta").Path
+		)
+
+		networkConfig.Storage.Allocations = append(
+			networkConfig.Storage.Allocations,
+			daecommon.ConfigStorageAllocation{
+				DataPath:  dataPath,
+				MetaPath:  metaPath,
+				Capacity:  1,
+				S3APIPort: 4900,
+				RPCPort:   4901,
+				AdminPort: 4902,
+			},
+		)
+
+		// Creating the directory is enough to ensure that Isle chooses LMDB as
+		// the db engine.
+		lmdbPath := filepath.Join(metaPath, "db.lmdb")
+		require.NoError(t, os.Mkdir(lmdbPath, 0755))
+
+		assert.NoError(t, network.SetConfig(h.ctx, networkConfig))
+
+		t.Log("Checking that garage is using the expected db engine")
+		garageConfig, err := os.ReadFile(
+			filepath.Join(network.runtimeDir.Path, "garage-4901.toml"),
+		)
+		assert.NoError(t, err)
+		assert.Contains(t,
+			string(garageConfig),
+			`db_engine = "`+garagesrv.DBEngineLMDB+`"`,
+		)
 	})
 
 	t.Run("remove storage alloc", func(t *testing.T) {

go/garage/garagesrv/garagesrv.go

@@ -14,6 +14,15 @@ import (
 	"strconv"
 )
 
+// DBEngine enumerates the garage db engines which are supported by Isle.
+type DBEngine string
+
+// Enumeration of DBEngine values.
+const (
+	DBEngineLMDB   DBEngine = "lmdb"
+	DBEngineSqlite DBEngine = "sqlite"
+)
+
 func nodeKeyPath(metaDirPath string) string {
 	return filepath.Join(metaDirPath, "node_key")
 }
@@ -150,3 +159,21 @@ func InitAlloc(metaDirPath string, initRPCPort int) (string, int, error) {
 
 	return pubKeyStr, rpcPort, nil
 }
+
+// GetDBEngine returns the DBEngine currently being used at a particular meta
+// data directory. Defaults to DBEngineSqlite if the directory doesn't exist or
+// hasn't been fully initialized yet.
+func GetDBEngine(metaDirPath string) (DBEngine, error) {
+	dbLMDBPath := filepath.Join(metaDirPath, "db.lmdb")
+
+	stat, err := os.Stat(dbLMDBPath)
+	if errors.Is(err, fs.ErrNotExist) {
+		return DBEngineSqlite, nil
+	} else if err != nil {
+		return "", fmt.Errorf("checking if %q exists: %w", dbLMDBPath, err)
+	} else if stat.IsDir() {
+		return DBEngineLMDB, nil
+	}
+
+	return DBEngineSqlite, nil
+}

go/garage/garagesrv/tpl.go

@@ -22,6 +22,7 @@ type GarageTomlData struct {
 
 	RPCSecret  string
 	AdminToken string
+	DBEngine   DBEngine
 
 	garage.LocalNode
 	BootstrapPeers []garage.RemoteNode
@@ -30,6 +31,7 @@ type GarageTomlData struct {
 var garageTomlTpl = template.Must(template.New("").Parse(`
 metadata_dir = "{{ .MetaPath }}"
 data_dir = "{{ .DataPath }}"
+db_engine = "{{ .DBEngine }}"
 
 replication_mode = "` + strconv.Itoa(garage.ReplicationFactor) + `"