From 4de0576c267c65ad53509765c124c443bcb49331 Mon Sep 17 00:00:00 2001
From: leo <wanderer@dotya.ml>
Date: Wed, 17 May 2023 13:35:13 +0200
Subject: [PATCH] go: add some more startup checks for DB

---
 error.go |  8 ++++++++
 run.go   | 13 ++++++++++++-
 2 files changed, 20 insertions(+), 1 deletion(-)
 create mode 100644 error.go

diff --git a/error.go b/error.go
new file mode 100644
index 0000000..ea895bd
--- /dev/null
+++ b/error.go
@@ -0,0 +1,8 @@
+package main
+
+import "errors"
+
+var (
+	errDBNotConfigured   = errors.New("Database connection string or database type were not set")
+	errUnsupportedDBType = errors.New("DBTYPE can only be one of postgres or sqlite3")
+)
diff --git a/run.go b/run.go
index da13f0b..0853c28 100644
--- a/run.go
+++ b/run.go
@@ -111,6 +111,17 @@ func run() error {
 	connstr := os.Getenv("PCMT_CONNSTRING")
 	dbtype := os.Getenv("PCMT_DBTYPE")
 
+	// check and bail early.
+	switch {
+	case connstr == "" || dbtype == "":
+		log.Errorf("PCMT_CONNSTRING or PCMT_DBTYPE or *both* were UNSET, bailing...")
+		return errDBNotConfigured
+
+	case dbtype != "postgres" && dbtype != "sqlite3":
+		log.Errorf("unsupported DB type specified, bailing...")
+		return errUnsupportedDBType
+	}
+
 	setting.SetDbConnstring(connstr)
 	// type can be one of "postgres" or "sqlite3".
 	setting.SetDbType(dbtype)
@@ -119,7 +130,7 @@ func run() error {
 
 	db, err := ent.Open(setting.DbType(), setting.DbConnstring())
 	if err != nil {
-		return fmt.Errorf("failed to open a connection to sqlite: %v", err)
+		return fmt.Errorf("failed to open a connection to database: %v", err)
 	}
 	defer db.Close()