SQLite allows having 1 set to MaxOpenConnections (#3941)

* let sqlite have a single concurrent connection

internal/clientcache/cmd/doc.go

@@ -6,4 +6,4 @@ Package cmd contains the command packages to the client cache. Adding
 these commands to the boundary cli is the only integration between the boundary
 binary and the client cache.
 */
-package cmd
+package cmd

internal/clientcache/internal/cache/store_test.go

@@ -5,6 +5,7 @@ package cache
 
 import (
 	"context"
+	"sync"
 	"testing"
 	"time"
 
@@ -506,3 +507,30 @@ func TestSession(t *testing.T) {
 		assert.ErrorContains(t, rw.LookupById(ctx, lookSess), "not found")
 	})
 }
+
+func TestRepository_SqliteReadDuringTx(t *testing.T) {
+	ctx := context.Background()
+	s, err := cachedb.Open(ctx)
+	require.NoError(t, err)
+	rw := db.New(s)
+
+	ret := AuthToken{
+		Id: "something",
+	}
+	assert.ErrorContains(t, rw.LookupById(ctx, &ret), "not found")
+
+	var startTx sync.WaitGroup
+	startTx.Add(1)
+	go func() {
+		_, err = rw.DoTx(ctx, db.StdRetryCnt, db.ExpBackoff{}, func(reader db.Reader, writer db.Writer) error {
+			startTx.Done()
+			time.Sleep(500 * time.Millisecond)
+
+			assert.ErrorContains(t, reader.LookupById(ctx, &ret), "not found")
+			return nil
+		})
+	}()
+	// setup a read that potentially executes during a tx
+	startTx.Wait()
+	assert.ErrorContains(t, rw.LookupById(ctx, &ret), "not found")
+}

internal/clientcache/internal/db/db.go

@@ -34,7 +34,9 @@ func Open(ctx context.Context, opt ...Option) (*db.DB, error) {
 	default:
 		url = DefaultStoreUrl
 	}
-	conn, err := db.Open(ctx, db.Sqlite, url)
+	// sqlite db must be set to 1 max open connection so requests can be serialized
+	// otherwise reading while a tx is ongoing results in sql logic errors.
+	conn, err := db.Open(ctx, db.Sqlite, url, db.WithMaxOpenConnections(1))
 	if err != nil {
 		return nil, errors.Wrap(ctx, err, op)
 	}

internal/db/db.go

@@ -174,7 +174,7 @@ func Open(ctx context.Context, dbType DbType, connectionUrl string, opt ...Optio
 		wrappedOpts = append(wrappedOpts, dbw.WithLogger(opts.withGormFormatter))
 	}
 	if opts.withMaxOpenConnections > 0 {
-		if opts.withMaxOpenConnections < 5 {
+		if opts.withMaxOpenConnections < 5 && dbType != Sqlite {
 			return nil, fmt.Errorf("max_open_connections cannot be below 5")
 		}
 		wrappedOpts = append(wrappedOpts, dbw.WithMaxOpenConnections(opts.withMaxOpenConnections))