feat: add database upgrade functionality (adapted from listmonk)

cmd/install.go

@@ -9,10 +9,10 @@ import (
 	"time"
 
 	"github.com/abhinavxd/libredesk/internal/colorlog"
+	"github.com/abhinavxd/libredesk/internal/dbutil"
 	"github.com/abhinavxd/libredesk/internal/user"
 	"github.com/jmoiron/sqlx"
 	"github.com/knadh/stuffbin"
-	"github.com/lib/pq"
 )
 
 // Install checks if the schema is already installed, prompts for confirmation, and installs the schema if needed.
@@ -76,7 +76,7 @@ func setSystemUserPass(ctx context.Context, db *sqlx.DB) {
 // checkSchema verifies if the DB schema is already installed by querying a table.
 func checkSchema(db *sqlx.DB) (bool, error) {
 	if _, err := db.Exec(`SELECT * FROM settings LIMIT 1`); err != nil {
-		if pqErr, ok := err.(*pq.Error); ok && pqErr.Code == "42P01" {
+		if dbutil.IsTableNotExistError(err) {
 			return false, nil
 		}
 		return false, err

cmd/main.go

@@ -50,7 +50,8 @@ var (
 	frontendDir = "frontend/dist"
 
 	// Injected at build time.
-	buildString = ""
+	buildString   string
+	versionString string
 )
 
 // App is the global app context which is passed and injected in the http handlers.
@@ -99,9 +100,8 @@ func main() {
 	}
 
 	// Build string injected at build time.
-	if buildString != "" {
-		colorlog.Green("Build: %s", buildString)
-	}
+	colorlog.Green("Build: %s", buildString)
+	colorlog.Green("Version: %s", versionString)
 
 	// Load the config files into Koanf.
 	initConfig(ko)
@@ -136,10 +136,13 @@ func main() {
 
 	// Upgrade.
 	if ko.Bool("upgrade") {
-		log.Println("no upgrades available")
+		upgrade(db, fs, !ko.Bool("yes"))
 		os.Exit(0)
 	}
 
+	// Check for pending upgrade.
+	checkPendingUpgrade(db)
+
 	// Load app settings from DB into the Koanf instance.
 	settings := initSettings(db)
 	loadSettings(settings)

cmd/upgrade.go

@@ -0,0 +1,145 @@
+// Copyright Kailash Nadh (https://github.com/knadh/listmonk)
+// SPDX-License-Identifier: AGPL-3.0
+// Adapted from listmonk for Libredesk.
+
+package main
+
+import (
+	"fmt"
+	"log"
+	"strings"
+
+	"github.com/abhinavxd/libredesk/internal/dbutil"
+	"github.com/jmoiron/sqlx"
+	"github.com/knadh/koanf/v2"
+	"github.com/knadh/stuffbin"
+	"golang.org/x/mod/semver"
+)
+
+// migFunc represents a migration function for a particular version.
+// fn (generally) executes database migrations and additionally
+// takes the filesystem and config objects in case there are additional bits
+// of logic to be performed before executing upgrades. fn is idempotent.
+type migFunc struct {
+	version string
+	fn      func(*sqlx.DB, stuffbin.FileSystem, *koanf.Koanf) error
+}
+
+// migList is the list of available migList ordered by the semver.
+// Each migration is a Go file in internal/migrations named after the semver.
+// The functions are named as: v0.7.0 => migrations.V0_7_0() and are idempotent.
+var migList = []migFunc{}
+
+// upgrade upgrades the database to the current version by running SQL migration files
+// for all version from the last known version to the current one.
+func upgrade(db *sqlx.DB, fs stuffbin.FileSystem, prompt bool) {
+	if prompt {
+		var ok string
+		fmt.Printf("** IMPORTANT: Take a backup of the database before upgrading.\n")
+		fmt.Print("continue (y/n)?  ")
+		if _, err := fmt.Scanf("%s", &ok); err != nil {
+			log.Fatalf("error reading value from terminal: %v", err)
+		}
+		if !strings.EqualFold(ok, "y") {
+			fmt.Println("upgrade cancelled")
+			return
+		}
+	}
+
+	_, toRun, err := getPendingMigrations(db)
+	if err != nil {
+		log.Fatalf("error checking migrations: %v", err)
+	}
+
+	// No migrations to run.
+	if len(toRun) == 0 {
+		log.Printf("no upgrades to run. Database is up to date.")
+		return
+	}
+
+	// Execute migrations in succession.
+	for _, m := range toRun {
+		log.Printf("running migration %s", m.version)
+		if err := m.fn(db, fs, ko); err != nil {
+			log.Fatalf("error running migration %s: %v", m.version, err)
+		}
+
+		// Record the migration version in the settings table. There was no
+		// settings table until v0.7.0, so ignore the no-table errors.
+		if err := recordMigrationVersion(m.version, db); err != nil {
+			if dbutil.IsTableNotExistError(err) {
+				continue
+			}
+			log.Fatalf("error recording migration version %s: %v", m.version, err)
+		}
+	}
+
+	log.Printf("upgrade complete")
+}
+
+// getPendingMigrations gets the pending migrations by comparing the last
+// recorded migration in the DB against all migrations listed in `migrations`.
+func getPendingMigrations(db *sqlx.DB) (string, []migFunc, error) {
+	lastVer, err := getLastMigrationVersion(db)
+	if err != nil {
+		return "", nil, err
+	}
+
+	// Iterate through the migration versions and get everything above the last
+	// upgraded semver.
+	var toRun []migFunc
+	for i, m := range migList {
+		if semver.Compare(m.version, lastVer) > 0 {
+			toRun = migList[i:]
+			break
+		}
+	}
+
+	return lastVer, toRun, nil
+}
+
+// getLastMigrationVersion returns the last migration semver recorded in the DB.
+// If there isn't any, `v0.0.0` is returned.
+func getLastMigrationVersion(db *sqlx.DB) (string, error) {
+	var v string
+	if err := db.Get(&v, `
+		SELECT COALESCE(
+			(SELECT value->>-1 FROM settings WHERE key='migrations'),
+		'v0.0.0')`); err != nil {
+		if dbutil.IsTableNotExistError(err) {
+			return "v0.0.0", nil
+		}
+		return v, err
+	}
+	return v, nil
+}
+
+// recordMigrationVersion inserts the given version (of DB migration) into the
+// `migrations` array in the settings table.
+func recordMigrationVersion(ver string, db *sqlx.DB) error {
+	_, err := db.Exec(fmt.Sprintf(`INSERT INTO settings (key, value)
+	VALUES('migrations', '["%s"]'::JSONB)
+	ON CONFLICT (key) DO UPDATE SET value = settings.value || EXCLUDED.value`, ver))
+	return err
+}
+
+// checkPendingUpgrade checks if the current database schema matches the expected binary version.
+func checkPendingUpgrade(db *sqlx.DB) {
+	lastVer, toRun, err := getPendingMigrations(db)
+	if err != nil {
+		log.Fatalf("error checking migrations: %v", err)
+	}
+
+	// No migrations to run.
+	if len(toRun) == 0 {
+		return
+	}
+
+	var vers []string
+	for _, m := range toRun {
+		vers = append(vers, m.version)
+	}
+
+	log.Fatalf(`there are %d pending database upgrade(s): %v. The last upgrade was %s. Backup the database and run libredesk --upgrade`,
+		len(toRun), vers, lastVer)
+}

internal/dbutil/dbutil.go

@@ -23,3 +23,14 @@ func IsUniqueViolationError(err error) bool {
 	}
 	return false
 }
+
+// IsTableNotExistError checks if the given error is a PostgreSQL table does not exist error (error code 42P01)
+func IsTableNotExistError(err error) bool {
+	if err == nil {
+		return false
+	}
+	if pqErr, ok := err.(*pq.Error); ok {
+		return pqErr.Code == "42P01"
+	}
+	return false
+}