sqldb: add the sqldb package

This commit provides the scaffolding for using the new sql stores.
The new interfaces, structs and methods are in sync with other projects
like Taproot Assets.

- Transactional Queries: the sqldb package defines the interfaces required
to execute transactional queries to our storage interface.

- Migration Files Embedded: the migration files are embedded into the binary.

- Database Migrations: I kept the use of 'golang-migrate' to ensure our
codebase remains in sync with the other projects, but can be changed.

- Build Flags for Conditional DB Target: flexibility to specify our database
target at compile-time based on the build flags in the same way we do
with our kv stores.

- Update modules: ran `go mod tidy`.

sqldb/postgres.go

@@ -0,0 +1,141 @@
+package sqldb
+
+import (
+	"database/sql"
+	"fmt"
+	"testing"
+	"time"
+
+	postgres_migrate "github.com/golang-migrate/migrate/v4/database/postgres"
+	_ "github.com/golang-migrate/migrate/v4/source/file" // Read migrations from files. // nolint:lll
+	"github.com/lightningnetwork/lnd/sqldb/sqlc"
+	"github.com/stretchr/testify/require"
+)
+
+const (
+	dsnTemplate = "postgres://%v:%v@%v:%d/%v?sslmode=%v"
+)
+
+var (
+	// DefaultPostgresFixtureLifetime is the default maximum time a Postgres
+	// test fixture is being kept alive. After that time the docker
+	// container will be terminated forcefully, even if the tests aren't
+	// fully executed yet. So this time needs to be chosen correctly to be
+	// longer than the longest expected individual test run time.
+	DefaultPostgresFixtureLifetime = 10 * time.Minute
+)
+
+// PostgresConfig holds the postgres database configuration.
+//
+//nolint:lll
+type PostgresConfig struct {
+	SkipMigrations     bool   `long:"skipmigrations" description:"Skip applying migrations on startup."`
+	Host               string `long:"host" description:"Database server hostname."`
+	Port               int    `long:"port" description:"Database server port."`
+	User               string `long:"user" description:"Database user."`
+	Password           string `long:"password" description:"Database user's password."`
+	DBName             string `long:"dbname" description:"Database name to use."`
+	MaxOpenConnections int    `long:"maxconnections" description:"Max open connections to keep alive to the database server."`
+	RequireSSL         bool   `long:"requiressl" description:"Whether to require using SSL (mode: require) when connecting to the server."`
+}
+
+// DSN returns the dns to connect to the database.
+func (s *PostgresConfig) DSN(hidePassword bool) string {
+	var sslMode = "disable"
+	if s.RequireSSL {
+		sslMode = "require"
+	}
+
+	password := s.Password
+	if hidePassword {
+		// Placeholder used for logging the DSN safely.
+		password = "****"
+	}
+
+	return fmt.Sprintf(dsnTemplate, s.User, password, s.Host, s.Port,
+		s.DBName, sslMode)
+}
+
+// PostgresStore is a database store implementation that uses a Postgres
+// backend.
+type PostgresStore struct {
+	cfg *PostgresConfig
+
+	*BaseDB
+}
+
+// NewPostgresStore creates a new store that is backed by a Postgres database
+// backend.
+func NewPostgresStore(cfg *PostgresConfig) (*PostgresStore, error) {
+	log.Infof("Using SQL database '%s'", cfg.DSN(true))
+
+	rawDB, err := sql.Open("pgx", cfg.DSN(false))
+	if err != nil {
+		return nil, err
+	}
+
+	maxConns := defaultMaxConns
+	if cfg.MaxOpenConnections > 0 {
+		maxConns = cfg.MaxOpenConnections
+	}
+
+	rawDB.SetMaxOpenConns(maxConns)
+	rawDB.SetMaxIdleConns(maxConns)
+	rawDB.SetConnMaxLifetime(connIdleLifetime)
+
+	if !cfg.SkipMigrations {
+		// Now that the database is open, populate the database with
+		// our set of schemas based on our embedded in-memory file
+		// system.
+		//
+		// First, we'll need to open up a new migration instance for
+		// our current target database: sqlite.
+		driver, err := postgres_migrate.WithInstance(
+			rawDB, &postgres_migrate.Config{},
+		)
+		if err != nil {
+			return nil, err
+		}
+
+		postgresFS := newReplacerFS(sqlSchemas, map[string]string{
+			"BLOB":                "BYTEA",
+			"INTEGER PRIMARY KEY": "SERIAL PRIMARY KEY",
+			"TIMESTAMP":           "TIMESTAMP WITHOUT TIME ZONE",
+		})
+
+		err = applyMigrations(
+			postgresFS, driver, "sqlc/migrations", cfg.DBName,
+		)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	queries := sqlc.New(rawDB)
+
+	return &PostgresStore{
+		cfg: cfg,
+		BaseDB: &BaseDB{
+			DB:      rawDB,
+			Queries: queries,
+		},
+	}, nil
+}
+
+// NewTestPostgresDB is a helper function that creates a Postgres database for
+// testing.
+func NewTestPostgresDB(t *testing.T) *PostgresStore {
+	t.Helper()
+
+	t.Logf("Creating new Postgres DB for testing")
+
+	sqlFixture := NewTestPgFixture(t, DefaultPostgresFixtureLifetime)
+	store, err := NewPostgresStore(sqlFixture.GetConfig())
+	require.NoError(t, err)
+
+	t.Cleanup(func() {
+		sqlFixture.TearDown(t)
+	})
+
+	return store
+}