go-raw: handle DBHOST env variable expansion in the application

This removes some duplication from the setup shell scripts and makes it easier
to specify database location when running the application outside of TFB
framework.

frameworks/Go/go-raw/setup.sh

@@ -1,7 +1,5 @@
 #!/bin/bash
 
-sed -i 's|tcp(.*:3306)|tcp('"${DBHOST}"':3306)|g' src/hello/hello.go
-
 fw_depends go
 
 go get ./...

frameworks/Go/go-raw/setup_prefork.sh

@@ -1,7 +1,5 @@
 #!/bin/bash
 
-sed -i 's|tcp(.*:3306)|tcp('"${DBHOST}"':3306)|g' src/hello/hello.go
-
 fw_depends go
 
 go get ./...

frameworks/Go/go-raw/src/hello/hello.go

@@ -4,6 +4,7 @@ import (
 	"database/sql"
 	"encoding/json"
 	"flag"
+	"fmt"
 	"html/template"
 	"log"
 	"math/rand"
@@ -41,7 +42,7 @@ const (
 	// It reduces round trips without prepared statement.
 	//
 	// We can see difference between prepared statement and interpolation by comparing go-raw and go-raw-interpolate
-	connectionString = "benchmarkdbuser:benchmarkdbpass@tcp(localhost:3306)/hello_world?interpolateParams=true"
+	connectionString = "benchmarkdbuser:benchmarkdbpass@tcp(%s:3306)/hello_world?interpolateParams=true"
 	worldSelect      = "SELECT id, randomNumber FROM World WHERE id = ?"
 	worldUpdate      = "UPDATE World SET randomNumber = ? WHERE id = ?"
 	fortuneSelect    = "SELECT id, message FROM Fortune"
@@ -67,7 +68,11 @@ var child = flag.Bool("child", false, "is child proc")
 
 func initDB() {
 	var err error
-	db, err = sql.Open("mysql", connectionString)
+	var dbhost = os.Getenv("DBHOST")
+	if dbhost == "" {
+		dbhost = "localhost"
+	}
+	db, err = sql.Open("mysql", fmt.Sprintf(connectionString, dbhost))
 	if err != nil {
 		log.Fatalf("Error opening database: %v", err)
 	}