Add migrate-list subcommand that lists available migrations

Here, add a new `migrate-list` command to the River CLI. It prints the
versions and names of available migrations along with an indicator as to
the current state of the database:

    $ go run ./cmd/river migrate-list --database-url postgres:///river_dev
      001 create river migration
      002 initial schema
      003 river job tags non null
      004 pending and more
    * 005 migration unique client

It's pretty far from a high priority feature, but I started it a few
weeks ago and I figured I may as well finish it. I started because I
realized that despite having a `migrate-get` command, there was no way
to figure out what migrations actually existed before you ran it.

I bring in a test convention for CLI commands so we can start trying to
check with more authority that things like expected output stay stable.
(Previously, we weren't testing commands except to vet that they will
run successfully in CI.) This approach uses mocks because we still have
no way of reusing database-based testing infrastructure outside the main
package (eventually some of it should go into `rivershared`), but
despite that, it should give us reasonable assuredness for now.

.github/workflows/ci.yaml

@@ -160,6 +160,10 @@ jobs:
         run: river migrate-up --database-url $DATABASE_URL
         shell: bash
 
+      - name: river migrate-list
+        run: river migrate-list --database-url $DATABASE_URL
+        shell: bash
+
       - name: river validate
         run: river validate --database-url $DATABASE_URL
         shell: bash

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- A new `river migrate-list` command is available which lists available migrations and which version a target database is migrated to. [PR #XXX](https://github.com/riverqueue/river/pull/XXX).
+
 ## [0.11.2] - 2024-08-08
 
 ### Fixed

cmd/river/rivercli/command.go

@@ -29,6 +29,7 @@ type BenchmarkerInterface interface {
 // around without having to know the transaction type.
 type MigratorInterface interface {
 	AllVersions() []rivermigrate.Migration
+	ExistingVersions(ctx context.Context) ([]rivermigrate.Migration, error)
 	GetVersion(version int) (rivermigrate.Migration, error)
 	Migrate(ctx context.Context, direction rivermigrate.Direction, opts *rivermigrate.MigrateOpts) (*rivermigrate.MigrateResult, error)
 	Validate(ctx context.Context) (*rivermigrate.ValidateResult, error)
@@ -39,6 +40,7 @@ type MigratorInterface interface {
 // CommandBase.
 type Command[TOpts CommandOpts] interface {
 	Run(ctx context.Context, opts TOpts) (bool, error)
+	GetCommandBase() *CommandBase
 	SetCommandBase(b *CommandBase)
 }
 
@@ -53,9 +55,8 @@ type CommandBase struct {
 	GetMigrator    func(config *rivermigrate.Config) MigratorInterface
 }
 
-func (b *CommandBase) SetCommandBase(base *CommandBase) {
-	*b = *base
-}
+func (b *CommandBase) GetCommandBase() *CommandBase     { return b }
+func (b *CommandBase) SetCommandBase(base *CommandBase) { *b = *base }
 
 // CommandOpts are options for a command options. It makes sure that options
 // provide a way of validating themselves.
@@ -103,7 +104,7 @@ func RunCommand[TOpts CommandOpts](ctx context.Context, bundle *RunCommandBundle
 			commandBase.GetMigrator = func(config *rivermigrate.Config) MigratorInterface { return rivermigrate.New(driver, config) }
 
 		default:
-			return false, errors.New("unsupport database URL; try one with a prefix of `postgres://...`")
+			return false, errors.New("unsupported database URL; try one with a prefix of `postgres://...`")
 		}
 
 		command.SetCommandBase(commandBase)

cmd/river/rivercli/river_cli.go

@@ -94,7 +94,7 @@ Provides command line facilities for the River job queue.
 	}
 
 	addDatabaseURLFlag := func(cmd *cobra.Command, databaseURL *string) {
-		cmd.Flags().StringVar(databaseURL, "database-url", "", "URL of the database to benchmark (should look like `postgres://...`")
+		cmd.Flags().StringVar(databaseURL, "database-url", "", "URL of the database (should look like `postgres://...`")
 		mustMarkFlagRequired(cmd, "database-url")
 	}
 	addLineFlag := func(cmd *cobra.Command, line *string) {
@@ -215,6 +215,25 @@ framework, which aren't necessary if using an external framework:
 		rootCmd.AddCommand(cmd)
 	}
 
+	// migrate-list
+	{
+		var opts migrateListOpts
+
+		cmd := &cobra.Command{
+			Use:   "migrate-list",
+			Short: "List River schema migrations",
+			Long: strings.TrimSpace(`
+TODO
+	`),
+			Run: func(cmd *cobra.Command, args []string) {
+				RunCommand(ctx, makeCommandBundle(&opts.DatabaseURL), &migrateList{}, &opts)
+			},
+		}
+		addDatabaseURLFlag(cmd, &opts.DatabaseURL)
+		cmd.Flags().StringVar(&opts.Line, "line", "", "migration line to operate on (default: main)")
+		rootCmd.AddCommand(cmd)
+	}
+
 	// migrate-up
 	{
 		var opts migrateOpts
@@ -259,6 +278,7 @@ migrations that need to be run, but without running them.
 			},
 		}
 		addDatabaseURLFlag(cmd, &opts.DatabaseURL)
+		mustMarkFlagRequired(cmd, "database-url")
 		cmd.Flags().StringVar(&opts.Line, "line", "", "migration line to operate on (default: main)")
 		rootCmd.AddCommand(cmd)
 	}
@@ -450,6 +470,47 @@ func (c *migrateGet) Run(_ context.Context, opts *migrateGetOpts) (bool, error)
 	return true, nil
 }
 
+type migrateListOpts struct {
+	DatabaseURL string
+	Line        string
+}
+
+func (o *migrateListOpts) Validate() error { return nil }
+
+type migrateList struct {
+	CommandBase
+}
+
+func (c *migrateList) Run(ctx context.Context, opts *migrateListOpts) (bool, error) {
+	migrator := c.GetMigrator(&rivermigrate.Config{Line: opts.Line, Logger: c.Logger})
+
+	allMigrations := migrator.AllVersions()
+
+	existingMigrations, err := migrator.ExistingVersions(ctx)
+	if err != nil {
+		return false, err
+	}
+
+	var maxExistingVersion int
+	if len(existingMigrations) > 0 {
+		maxExistingVersion = existingMigrations[len(existingMigrations)-1].Version
+	}
+
+	for _, migration := range allMigrations {
+		var currentVersionPrefix string
+		switch {
+		case migration.Version == maxExistingVersion:
+			currentVersionPrefix = "* "
+		case maxExistingVersion > 0:
+			currentVersionPrefix = "  "
+		}
+
+		fmt.Fprintf(c.Out, "%s%03d %s\n", currentVersionPrefix, migration.Version, migration.Name)
+	}
+
+	return true, nil
+}
+
 type migrateUp struct {
 	CommandBase
 }

cmd/river/rivercli/river_cli_test.go

@@ -1,14 +1,149 @@
 package rivercli
 
 import (
+	"bytes"
+	"context"
+	"strings"
 	"testing"
 	"time"
 
 	"github.com/stretchr/testify/require"
 
 	"github.com/riverqueue/river/rivermigrate"
+	"github.com/riverqueue/river/rivershared/riversharedtest"
 )
 
+type MigratorStub struct {
+	allVersionsStub      func() []rivermigrate.Migration
+	existingVersionsStub func(ctx context.Context) ([]rivermigrate.Migration, error)
+	getVersionStub       func(version int) (rivermigrate.Migration, error)
+	migrateStub          func(ctx context.Context, direction rivermigrate.Direction, opts *rivermigrate.MigrateOpts) (*rivermigrate.MigrateResult, error)
+	validateStub         func(ctx context.Context) (*rivermigrate.ValidateResult, error)
+}
+
+func (m *MigratorStub) AllVersions() []rivermigrate.Migration {
+	if m.allVersionsStub == nil {
+		panic("AllVersions is not stubbed")
+	}
+
+	return m.allVersionsStub()
+}
+
+func (m *MigratorStub) ExistingVersions(ctx context.Context) ([]rivermigrate.Migration, error) {
+	if m.allVersionsStub == nil {
+		panic("ExistingVersions is not stubbed")
+	}
+
+	return m.existingVersionsStub(ctx)
+}
+
+func (m *MigratorStub) GetVersion(version int) (rivermigrate.Migration, error) {
+	if m.allVersionsStub == nil {
+		panic("GetVersion is not stubbed")
+	}
+
+	return m.getVersionStub(version)
+}
+
+func (m *MigratorStub) Migrate(ctx context.Context, direction rivermigrate.Direction, opts *rivermigrate.MigrateOpts) (*rivermigrate.MigrateResult, error) {
+	if m.allVersionsStub == nil {
+		panic("Migrate is not stubbed")
+	}
+
+	return m.migrateStub(ctx, direction, opts)
+}
+
+func (m *MigratorStub) Validate(ctx context.Context) (*rivermigrate.ValidateResult, error) {
+	if m.allVersionsStub == nil {
+		panic("Validate is not stubbed")
+	}
+
+	return m.validateStub(ctx)
+}
+
+var (
+	testMigration01 = rivermigrate.Migration{Name: "1st migration", SQLDown: "SELECT 1", SQLUp: "SELECT 1", Version: 1} //nolint:gochecknoglobals
+	testMigration02 = rivermigrate.Migration{Name: "2nd migration", SQLDown: "SELECT 1", SQLUp: "SELECT 1", Version: 2} //nolint:gochecknoglobals
+	testMigration03 = rivermigrate.Migration{Name: "3rd migration", SQLDown: "SELECT 1", SQLUp: "SELECT 1", Version: 3} //nolint:gochecknoglobals
+
+	testMigrationAll = []rivermigrate.Migration{testMigration01, testMigration02, testMigration03} //nolint:gochecknoglobals
+)
+
+func TestMigrateList(t *testing.T) {
+	t.Parallel()
+
+	ctx := context.Background()
+
+	type testBundle struct {
+		buf          *bytes.Buffer
+		migratorStub *MigratorStub
+	}
+
+	setup := func(t *testing.T) (*migrateList, *testBundle) {
+		t.Helper()
+
+		cmd, buf := withMigrateBase(t, &migrateList{})
+
+		migratorStub := &MigratorStub{}
+		migratorStub.allVersionsStub = func() []rivermigrate.Migration { return testMigrationAll }
+		migratorStub.existingVersionsStub = func(ctx context.Context) ([]rivermigrate.Migration, error) { return nil, nil }
+
+		cmd.GetCommandBase().GetMigrator = func(config *rivermigrate.Config) MigratorInterface { return migratorStub }
+
+		return cmd, &testBundle{
+			buf:          buf,
+			migratorStub: migratorStub,
+		}
+	}
+
+	t.Run("NoExistingMigrations", func(t *testing.T) {
+		t.Parallel()
+
+		migrateList, bundle := setup(t)
+
+		_, err := migrateList.Run(ctx, &migrateListOpts{})
+		require.NoError(t, err)
+
+		require.Equal(t, strings.TrimSpace(`
+001 1st migration
+002 2nd migration
+003 3rd migration
+		`), strings.TrimSpace(bundle.buf.String()))
+	})
+
+	t.Run("WithExistingMigrations", func(t *testing.T) {
+		t.Parallel()
+
+		migrateList, bundle := setup(t)
+
+		bundle.migratorStub.existingVersionsStub = func(ctx context.Context) ([]rivermigrate.Migration, error) {
+			return []rivermigrate.Migration{testMigration01, testMigration02}, nil
+		}
+
+		_, err := migrateList.Run(ctx, &migrateListOpts{})
+		require.NoError(t, err)
+
+		require.Equal(t, strings.TrimSpace(`
+  001 1st migration
+* 002 2nd migration
+  003 3rd migration
+		`), strings.TrimSpace(bundle.buf.String()))
+	})
+}
+
+func withMigrateBase[TCommand Command[TOpts], TOpts CommandOpts](t *testing.T, cmd TCommand) (TCommand, *bytes.Buffer) {
+	t.Helper()
+
+	var buf bytes.Buffer
+	cmd.SetCommandBase(&CommandBase{
+		Logger: riversharedtest.Logger(t),
+		Out:    &buf,
+
+		GetMigrator: func(config *rivermigrate.Config) MigratorInterface { return &MigratorStub{} },
+	})
+	return cmd, &buf
+}
+
 func TestMigrationComment(t *testing.T) {
 	t.Parallel()
 

rivermigrate/river_migrate.go

@@ -132,6 +132,52 @@ func New[TTx any](driver riverdriver.Driver[TTx], config *Config) *Migrator[TTx]
 	})
 }
 
+// ExistingVersions gets the existing set of versions that have been migrated in
+// the database, ordered by version.
+func (m *Migrator[TTx]) ExistingVersions(ctx context.Context) ([]Migration, error) {
+	migrations, err := m.existingMigrations(ctx, m.driver.GetExecutor())
+	if err != nil {
+		return nil, err
+	}
+
+	versions, err := m.versionsFromDriver(migrations)
+	if err != nil {
+		return nil, err
+	}
+
+	return versions, nil
+}
+
+// ExistingVersions gets the existing set of versions that have been migrated in
+// the database, ordered by version.
+//
+// This variant checks for existing versions in a transaction.
+func (m *Migrator[TTx]) ExistingVersionsTx(ctx context.Context, tx TTx) ([]Migration, error) {
+	migrations, err := m.existingMigrations(ctx, m.driver.UnwrapExecutor(tx))
+	if err != nil {
+		return nil, err
+	}
+
+	versions, err := m.versionsFromDriver(migrations)
+	if err != nil {
+		return nil, err
+	}
+
+	return versions, nil
+}
+
+func (m *Migrator[TTx]) versionsFromDriver(migrations []*riverdriver.Migration) ([]Migration, error) {
+	versions := make([]Migration, len(migrations))
+	for i, existingMigration := range migrations {
+		migration, ok := m.migrations[existingMigration.Version]
+		if !ok {
+			return nil, fmt.Errorf("migration %d not found in migrator bundle", existingMigration.Version)
+		}
+		versions[i] = migration
+	}
+	return versions, nil
+}
+
 // MigrateOpts are options for a migrate operation.
 type MigrateOpts struct {
 	DryRun bool