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refactor: provide CLI app in a standalone package
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Users can start the tool from their own entrypoints by using buncli.New/Run etc.
They are also responsible for configuring the DB connection and AutoMigrator.

bundb/bunctl will eventually use FromPlugin() to read config from a pre-built plugin.
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@bevzzz
bevzzz committed Nov 26, 2024
1 parent 83bea5a commit 4967e7c
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Showing 7 changed files with 181 additions and 354 deletions.
357 changes: 3 additions & 354 deletions cmd/bundb/main.go
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Original file line number Diff line number Diff line change
Expand Up @@ -25,366 +25,15 @@ Although... this way we are moving towards a .bundb.config or something.
package main

import (
"bytes"
"database/sql"
"fmt"
"log"
"os"
"os/exec"
"path"
"plugin"
"strings"

"github.com/uptrace/bun"
"github.com/uptrace/bun/dialect/mssqldialect"
"github.com/uptrace/bun/dialect/mysqldialect"
"github.com/uptrace/bun/dialect/oracledialect"
"github.com/uptrace/bun/dialect/pgdialect"
"github.com/uptrace/bun/dialect/sqlitedialect"
"github.com/uptrace/bun/driver/pgdriver"
"github.com/uptrace/bun/driver/sqliteshim"
"github.com/uptrace/bun/migrate"
"github.com/uptrace/bun/schema"
"github.com/urfave/cli/v2"
"github.com/uptrace/bun/extra/buncli"
)

const (
defaultMigrationsDirectory = "./migrations"
pluginName = "plugin.so"
)

var (
supportedDrivers = []string{"postgres", "sqlserver", "mysql", "oci8", "file"}
autoMigratorOptions []migrate.AutoMigratorOption
migrationsDirectory string
)

var (
cleanup = &cli.BoolFlag{
Name: "cleanup",
}
)

var app = &cli.App{
Name: "bundb",
Usage: "Database migration tool for uptrace/bun",
Commands: cli.Commands{
// bundb init --create-directory
// bundb create --sql --go --tx [-d | --dir]
// bundb migrate
// bundb auto create --tx
// bundb auto migrate
&cli.Command{
Name: "auto",
Usage: "manage database schema with AutoMigrator",
Subcommands: cli.Commands{
&cli.Command{
Name: "create",
Usage: "Generate SQL migration files",
Flags: []cli.Flag{
&cli.StringFlag{
Name: "uri",
Aliases: []string{"database-uri", "dsn"},
Required: true,
EnvVars: []string{"BUNDB_URI"},
},
&cli.StringFlag{
Name: "driver",
},
&cli.StringFlag{
Name: "d",
Aliases: []string{"migrations-directory"},
Destination: &migrationsDirectory,
Value: defaultMigrationsDirectory,
Action: func(ctx *cli.Context, dir string) error {
autoMigratorOptions = append(autoMigratorOptions, migrate.WithMigrationsDirectoryAuto(dir))
return nil
},
},
&cli.StringFlag{
Name: "t",
Aliases: []string{"migrations-table"},
Action: func(ctx *cli.Context, migrationsTable string) error {
autoMigratorOptions = append(autoMigratorOptions, migrate.WithTableNameAuto(migrationsTable))
return nil
},
},
&cli.StringFlag{
Name: "l",
Aliases: []string{"locks", "migration-locks-table"},
Action: func(ctx *cli.Context, locksTable string) error {
autoMigratorOptions = append(autoMigratorOptions, migrate.WithLocksTableNameAuto(locksTable))
return nil
},
},
&cli.StringFlag{
Name: "s",
Aliases: []string{"schema"},
Action: func(ctx *cli.Context, schemaName string) error {
autoMigratorOptions = append(autoMigratorOptions, migrate.WithSchemaName(schemaName))
return nil
},
},
&cli.StringSliceFlag{
Name: "exclude",
Action: func(ctx *cli.Context, tables []string) error {
autoMigratorOptions = append(autoMigratorOptions, migrate.WithExcludeTable(tables...))
return nil
},
},
&cli.BoolFlag{
Name: "rebuild",
},
cleanup,
&cli.BoolFlag{
Name: "tx",
Aliases: []string{"transactional"},
},
},
Action: func(ctx *cli.Context) error {
if err := buildPlugin(ctx.Bool("rebuild")); err != nil {
return err
}

if cleanup.Get(ctx) {
defer deletePlugin()
}

db, err := connect(ctx.String("uri"), ctx.String("driver"), !ctx.IsSet("driver"))
if err != nil {
return err

}

if !ctx.IsSet("migrations-directory") {
autoMigratorOptions = append(autoMigratorOptions, migrate.WithMigrationsDirectoryAuto(defaultMigrationsDirectory))

}
m, err := automigrator(db)
if err != nil {
return err
}

if ctx.Bool("tx") {
_, err = m.CreateTxSQLMigrations(ctx.Context)
} else {
_, err = m.CreateSQLMigrations(ctx.Context)
}
if err != nil {
return err
}
return nil
},
},
&cli.Command{
Name: "migrate",
Usage: "Generate SQL migrations and apply them right away",
Flags: []cli.Flag{
&cli.StringFlag{
Name: "uri",
Aliases: []string{"database-uri", "dsn"},
Required: true,
EnvVars: []string{"BUNDB_URI"},
},
&cli.StringFlag{
Name: "driver",
},
&cli.StringFlag{
Name: "d",
Aliases: []string{"migrations-directory"},
Destination: &migrationsDirectory,
Value: defaultMigrationsDirectory,
Action: func(ctx *cli.Context, dir string) error {
autoMigratorOptions = append(autoMigratorOptions, migrate.WithMigrationsDirectoryAuto(dir))
return nil
},
},
&cli.StringFlag{
Name: "t",
Aliases: []string{"migrations-table"},
Action: func(ctx *cli.Context, migrationsTable string) error {
autoMigratorOptions = append(autoMigratorOptions, migrate.WithTableNameAuto(migrationsTable))
return nil
},
},
&cli.StringFlag{
Name: "l",
Aliases: []string{"locks", "migration-locks-table"},
Action: func(ctx *cli.Context, locksTable string) error {
autoMigratorOptions = append(autoMigratorOptions, migrate.WithLocksTableNameAuto(locksTable))
return nil
},
},
&cli.StringFlag{
Name: "s",
Aliases: []string{"schema"},
Action: func(ctx *cli.Context, schemaName string) error {
autoMigratorOptions = append(autoMigratorOptions, migrate.WithSchemaName(schemaName))
return nil
},
},
&cli.StringSliceFlag{
Name: "exclude",
Action: func(ctx *cli.Context, tables []string) error {
autoMigratorOptions = append(autoMigratorOptions, migrate.WithExcludeTable(tables...))
return nil
},
},
&cli.BoolFlag{
Name: "rebuild",
},
cleanup,
},
Action: func(ctx *cli.Context) error {
if err := buildPlugin(ctx.Bool("rebuild")); err != nil {
return err
}

if cleanup.Get(ctx) {
defer deletePlugin()
}

db, err := connect(ctx.String("uri"), ctx.String("driver"), !ctx.IsSet("driver"))
if err != nil {
return err

}

if !ctx.IsSet("migrations-directory") {
autoMigratorOptions = append(autoMigratorOptions, migrate.WithMigrationsDirectoryAuto(defaultMigrationsDirectory))

}
m, err := automigrator(db)
if err != nil {
return err
}

group, err := m.Migrate(ctx.Context)
if err != nil {
return err
}
if group.IsZero() {
log.Print("ok, nothing to migrate")
}
return nil
},
},
},
},
},
}

func pluginPath() string {
return path.Join(migrationsDirectory, pluginName)
}

// TODO: wrap Build and Open steps into a sync.OnceFunc, so that we could use the Plugin object in multiple places
// without having to worry if it has been compiled or not.
func buildPlugin(force bool) error {
if force {
if err := deletePlugin(); err != nil {
return err
}
}

// Cmd.Run returns *exec.ExitError which will only contain the exit code message in case of an error.
// Rather than logging "exit code 1" we want to output a more informative error, so we redirect the Stderr.
var errBuf bytes.Buffer

cmd := exec.Command("go", "build", "-C", migrationsDirectory, "-buildmode", "plugin", "-o", pluginName)
cmd.Stderr = &errBuf

err := cmd.Run()
if err != nil {
// TODO: if errBuf contains "no such file or directory" add the following to the error message:
// "Create 'migrations/' directory by running: bundb init --create-directory migrations/"
return fmt.Errorf("build %s: %s", pluginPath(), &errBuf)
}
return nil
}

func deletePlugin() error {
return os.RemoveAll(pluginPath())
}

// connect to the database under the URI. A driver must be one of the supported drivers.
// If not set explicitly, the name of the driver is guessed from the URI.
//
// Example:
//
// "postgres://root:@localhost:5432/test" -> "postgres"
func connect(uri, driverName string, guessDriver bool) (*bun.DB, error) {
var sqldb *sql.DB
var dialect schema.Dialect
var err error

if guessDriver {
driver, _, found := strings.Cut(uri, ":")
if !found {
return nil, fmt.Errorf("driver cannot be guessed from connection string; pass -driver option explicitly")
}
driverName = driver
}

switch driverName {
case "postgres":
sqldb = sql.OpenDB(pgdriver.NewConnector(pgdriver.WithDSN(uri)))
dialect = pgdialect.New()
case "sqlserver":
sqldb, err = sql.Open(driverName, uri)
dialect = mssqldialect.New()
case "file":
sqldb, err = sql.Open(sqliteshim.ShimName, uri)
dialect = sqlitedialect.New()
case "mysql":
sqldb, err = sql.Open(driverName, uri)
dialect = mysqldialect.New()
case "oci8":
sqldb, err = sql.Open(driverName, uri)
dialect = oracledialect.New()
default:
err = fmt.Errorf("driver %q not recognized, supported drivers are %+v", driverName, supportedDrivers)
}

if err != nil {
return nil, err
}

return bun.NewDB(sqldb, dialect), nil
}

// automigrator creates AutoMigrator for models from user's 'migrations' package.
func automigrator(db *bun.DB) (*migrate.AutoMigrator, error) {
sym, err := lookup("Models")
if err != nil {
return nil, err
}

models, ok := sym.(*[]interface{})
if !ok {
return nil, fmt.Errorf("migrations plugin must export Models as []interface{}, got %T", models)
}
autoMigratorOptions = append(autoMigratorOptions, migrate.WithModel(*models...))

auto, err := migrate.NewAutoMigrator(db, autoMigratorOptions...)
if err != nil {
return nil, err
}
return auto, nil
}

// lookup a symbol from user's migrations plugin.
func lookup(symbol string) (plugin.Symbol, error) {
p, err := plugin.Open(pluginPath())
if err != nil {
return nil, err
}
return p.Lookup(symbol)
}

func main() {
log.SetPrefix("bundb: ")
if err := app.Run(os.Args); err != nil {
log.Fatal(err)
// TODO: use buncli.New(buncli.FromPlugin()) to read config from plugin
if err := buncli.Run(os.Args, nil); err != nil {

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}
}
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