api: retry database connection if it fails

Closes https://gitlab.com/commento/commento-ce/issues/52

api/database_connect.go

@@ -1,12 +1,13 @@
 package main
 
 import (
+	"time"
 	"database/sql"
 	_ "github.com/lib/pq"
 	"os"
 )
 
-func connectDB() error {
+func connectDB(retriesLeft int) error {
 	con := os.Getenv("POSTGRES")
 	logger.Infof("opening connection to postgres: %s", con)
 
@@ -17,6 +18,18 @@ func connectDB() error {
 		return err
 	}
 
+	err = db.Ping()
+	if err != nil {
+		if retriesLeft > 0 {
+			logger.Errorf("cannot talk to postgres, retrying in 10 seconds (%d attempts left): %v", retriesLeft-1, err)
+			time.Sleep(10 * time.Second)
+			return connectDB(retriesLeft - 1)
+		} else {
+			logger.Errorf("cannot talk to postgres, last attempt failed: %v", err)
+			return err
+		}
+	}
+
 	statement := `
     CREATE TABLE IF NOT EXISTS migrations (
       filename TEXT NOT NULL UNIQUE

api/main.go

@@ -3,7 +3,7 @@ package main
 func main() {
 	exitIfError(createLogger())
 	exitIfError(parseConfig())
-	exitIfError(connectDB())
+	exitIfError(connectDB(5))
 	exitIfError(performMigrations())
 	exitIfError(smtpConfigure())
 	exitIfError(smtpTemplatesLoad())

api/testing.go

@@ -68,7 +68,7 @@ func setupTestDatabase() error {
 		os.Setenv("POSTGRES", "postgres://postgres:postgres@localhost/commento_test?sslmode=disable")
 	}
 
-	if err := connectDB(); err != nil {
+	if err := connectDB(0); err != nil {
 		return err
 	}