From 602a908d7b31c1ed4c5c3c32899b3cc94613077e Mon Sep 17 00:00:00 2001
From: Sean Chittenden <sean@chittenden.org>
Date: Sun, 6 Nov 2016 01:23:33 -0700
Subject: [PATCH] Add a `fallback_application_name` to the PostgreSQL DSN.

---
 builtin/providers/postgresql/config.go   | 20 ++++++++++------
 builtin/providers/postgresql/provider.go | 29 +++++++++++++++++++-----
 2 files changed, 36 insertions(+), 13 deletions(-)

diff --git a/builtin/providers/postgresql/config.go b/builtin/providers/postgresql/config.go
index c096eb6e2..1021e7f28 100644
--- a/builtin/providers/postgresql/config.go
+++ b/builtin/providers/postgresql/config.go
@@ -3,18 +3,20 @@ package postgresql
 import (
 	"database/sql"
 	"fmt"
+	"log"
 
 	_ "github.com/lib/pq" //PostgreSQL db
 )
 
 // Config - provider config
 type Config struct {
-	Host     string
-	Port     int
-	Username string
-	Password string
-	SslMode  string
-	Timeout  int
+	Host            string
+	Port            int
+	Username        string
+	Password        string
+	SslMode         string
+	Timeout         int
+	ApplicationName string
 }
 
 // Client struct holding connection string
@@ -25,8 +27,12 @@ type Client struct {
 
 // NewClient returns new client config
 func (c *Config) NewClient() (*Client, error) {
-	connStr := fmt.Sprintf("host=%s port=%d user=%s password=%s dbname=postgres sslmode=%s connect_timeout=%d", c.Host, c.Port, c.Username, c.Password, c.SslMode, c.Timeout)
+	const dsnFmt = "host=%s port=%d user=%s password=%s sslmode=%s fallback_application_name=%s connect_timeout=%d"
 
+	logDSN := fmt.Sprintf(dsnFmt, c.Host, c.Port, c.Username, "<redacted>", c.SSLMode, c.ApplicationName)
+	log.Printf("[INFO] PostgreSQL DSN: `%s`", logDSN)
+
+	connStr := fmt.Sprintf(dsnFmt, c.Host, c.Port, c.Username, c.Password, c.SSLMode, c.ApplicationName, c.Timeout)
 	client := Client{
 		connStr:  connStr,
 		username: c.Username,
diff --git a/builtin/providers/postgresql/provider.go b/builtin/providers/postgresql/provider.go
index c0be6f08d..7046793c1 100644
--- a/builtin/providers/postgresql/provider.go
+++ b/builtin/providers/postgresql/provider.go
@@ -1,6 +1,9 @@
 package postgresql
 
 import (
+	"bytes"
+	"fmt"
+
 	"github.com/hashicorp/errwrap"
 	"github.com/hashicorp/terraform/helper/schema"
 	"github.com/hashicorp/terraform/terraform"
@@ -64,12 +67,13 @@ func Provider() terraform.ResourceProvider {
 
 func providerConfigure(d *schema.ResourceData) (interface{}, error) {
 	config := Config{
-		Host:     d.Get("host").(string),
-		Port:     d.Get("port").(int),
-		Username: d.Get("username").(string),
-		Password: d.Get("password").(string),
-		Timeout:  d.Get("connect_timeout").(int),
-		SslMode:  d.Get("sslmode").(string),
+		Host:            d.Get("host").(string),
+		Port:            d.Get("port").(int),
+		Username:        d.Get("username").(string),
+		Password:        d.Get("password").(string),
+		Timeout:         d.Get("connect_timeout").(int),
+		SslMode:         d.Get("sslmode").(string),
+		ApplicationName: tfAppName(),
 	}
 
 	client, err := config.NewClient()
@@ -79,3 +83,16 @@ func providerConfigure(d *schema.ResourceData) (interface{}, error) {
 
 	return client, nil
 }
+
+func tfAppName() string {
+	const VersionPrerelease = terraform.VersionPrerelease
+	var versionString bytes.Buffer
+
+	fmt.Fprintf(&versionString, "'Terraform v%s", terraform.Version)
+	if terraform.VersionPrerelease != "" {
+		fmt.Fprintf(&versionString, "-%s", terraform.VersionPrerelease)
+	}
+	fmt.Fprintf(&versionString, "'")
+
+	return versionString.String()
+}