From c3516dd184f4ed0222b1a967ca9552b001f309a5 Mon Sep 17 00:00:00 2001
From: Vivek Patel <ervicpatelwork@gmail.com>
Date: Tue, 4 Jan 2022 15:42:24 +0530
Subject: [PATCH] Allow version in DB_DSN for dev mode

If server is executed through Makefile we set BUILD_VERSION in .env and use it to replace {version} in DB_DSN.

This would help developers to automatically use different db when switching between versions.
---
 .env.example       |  4 ++++
 app/boot_levels.go |  2 +-
 store/connect.go   | 25 ++++++++++++++++++++++++-
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/.env.example b/.env.example
index 23cbb3253..374bcfaec 100644
--- a/.env.example
+++ b/.env.example
@@ -36,6 +36,10 @@ HTTP_LOG_REQUESTS=true
 MONITOR_INTERVAL=5min
 
 # Database to use
+#
+# If you are in development environment,
+# you can use {version} with database name, that will be replaced with build version
+# IE. DB_DSN=corteza:corteza@tcp(localhost:3306)/corteza_{version}?collation=utf8mb4_general_ci
 DB_DSN=corteza:corteza@tcp(localhost:3306)/corteza?collation=utf8mb4_general_ci
 
 # Log database queries?
diff --git a/app/boot_levels.go b/app/boot_levels.go
index 686391929..ba5c48cf7 100644
--- a/app/boot_levels.go
+++ b/app/boot_levels.go
@@ -181,7 +181,7 @@ func (app *CortezaApp) InitStore(ctx context.Context) (err error) {
 	if app.Store == nil {
 		defer sentry.Recover()
 
-		app.Store, err = store.Connect(ctx, app.Opt.DB.DSN)
+		app.Store, err = store.Connect(ctx, app.Log, app.Opt.DB.DSN, app.Opt.Environment.IsDevelopment())
 		if err != nil {
 			return err
 		}
diff --git a/store/connect.go b/store/connect.go
index 2d54582ba..6d7270783 100644
--- a/store/connect.go
+++ b/store/connect.go
@@ -3,6 +3,9 @@ package store
 import (
 	"context"
 	"fmt"
+	"go.uber.org/zap"
+	"os"
+	"regexp"
 	"strings"
 )
 
@@ -14,7 +17,27 @@ var (
 	registered = make(map[string]ConnectorFn)
 )
 
-func Connect(ctx context.Context, dsn string) (s Storer, err error) {
+// Connect returns store based on dsn from environment.
+//
+// If you are in development environment,
+// you can use {version} with database name, that will be replaced with build version
+// suppose build version is `20xx.x.x-dev-1` then database_name_{version} will be `database_name_20xx_x_x_dev_1`,
+//
+// IE. `BUILD_VERSION=20xx.x.x-dev-1` and
+// `DB_DSN=corteza:corteza@tcp(localhost:3306)/corteza_{version}?collation=utf8mb4_general_ci`
+// will be `DB_DSN=corteza:corteza@tcp(localhost:3306)/corteza_20xx_x_x_dev_1?collation=utf8mb4_general_ci`
+func Connect(ctx context.Context, log *zap.Logger, dsn string, isDevelopment bool) (s Storer, err error) {
+	if isDevelopment {
+		if strings.Contains(dsn, "{version}") {
+			log.Warn("You're using DB_DSN with {version}, It is still in EXPERIMENTAL phase")
+			log.Warn("Should be used only for development mode")
+			log.Warn("You may experience instability")
+		}
+		expr := regexp.MustCompile(`[.\-]+`)
+		version := expr.ReplaceAllString(os.Getenv("BUILD_VERSION"), "_")
+		dsn = strings.Replace(dsn, "{version}", version, 1)
+	}
+
 	var storeType = strings.SplitN(dsn, "://", 2)[0]
 	if storeType == "" {
 		// Backward compatibility