From 45ef11e59f443c43b42fe2d36c639c55bb0b1fbd Mon Sep 17 00:00:00 2001
From: Koen De Causmaecker <koen.decausmaecker@tomtom.com>
Date: Wed, 9 Sep 2015 14:06:53 +0200
Subject: [PATCH] provider/aws: aws_db_instance: unrequire fields

When spinning up from a snapshot or a read replica, these fields are
now optional:
* allocated_storage
* engine
* password
* username

Some validation logic is added to make these fields required when
starting a database from scratch.
The documentation is updated accordingly.
---
 .../providers/aws/resource_aws_db_instance.go | 23 +++++++++++++++----
 .../providers/aws/r/db_instance.html.markdown |  8 +++----
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/builtin/providers/aws/resource_aws_db_instance.go b/builtin/providers/aws/resource_aws_db_instance.go
index 00de73fc7..9bc6669a5 100644
--- a/builtin/providers/aws/resource_aws_db_instance.go
+++ b/builtin/providers/aws/resource_aws_db_instance.go
@@ -38,18 +38,20 @@ func resourceAwsDbInstance() *schema.Resource {
 
 			"username": &schema.Schema{
 				Type:     schema.TypeString,
-				Required: true,
+				Optional: true,
+				Computed: true,
 				ForceNew: true,
 			},
 
 			"password": &schema.Schema{
 				Type:     schema.TypeString,
-				Required: true,
+				Optional: true,
 			},
 
 			"engine": &schema.Schema{
 				Type:     schema.TypeString,
-				Required: true,
+				Optional: true,
+				Computed: true,
 				ForceNew: true,
 				StateFunc: func(v interface{}) string {
 					value := v.(string)
@@ -71,7 +73,8 @@ func resourceAwsDbInstance() *schema.Resource {
 
 			"allocated_storage": &schema.Schema{
 				Type:     schema.TypeInt,
-				Required: true,
+				Optional: true,
+				Computed: true,
 			},
 
 			"storage_type": &schema.Schema{
@@ -405,6 +408,18 @@ func resourceAwsDbInstanceCreate(d *schema.ResourceData, meta interface{}) error
 
 		}
 	} else {
+		if _, ok := d.GetOk("allocated_storage"); !ok {
+			return fmt.Errorf(`provider.aws: aws_db_instance: %s: "allocated_storage": required field is not set`, d.Get("name").(string))
+		}
+		if _, ok := d.GetOk("engine"); !ok {
+			return fmt.Errorf(`provider.aws: aws_db_instance: %s: "engine": required field is not set`, d.Get("name").(string))
+		}
+		if _, ok := d.GetOk("password"); !ok {
+			return fmt.Errorf(`provider.aws: aws_db_instance: %s: "password": required field is not set`, d.Get("name").(string))
+		}
+		if _, ok := d.GetOk("username"); !ok {
+			return fmt.Errorf(`provider.aws: aws_db_instance: %s: "username": required field is not set`, d.Get("name").(string))
+		}
 		opts := rds.CreateDBInstanceInput{
 			AllocatedStorage:        aws.Int64(int64(d.Get("allocated_storage").(int))),
 			DBName:                  aws.String(d.Get("name").(string)),
diff --git a/website/source/docs/providers/aws/r/db_instance.html.markdown b/website/source/docs/providers/aws/r/db_instance.html.markdown
index 2c045773c..f3e4eb708 100644
--- a/website/source/docs/providers/aws/r/db_instance.html.markdown
+++ b/website/source/docs/providers/aws/r/db_instance.html.markdown
@@ -48,8 +48,8 @@ the [AWS official documentation](http://docs.aws.amazon.com/AmazonRDS/latest/Com
 
 The following arguments are supported:
 
-* `allocated_storage` - (Required) The allocated storage in gigabytes.
-* `engine` - (Required) The database engine to use.
+* `allocated_storage` - (Required unless a `snapshot_identifier` or `replicate_source_db` is provided) The allocated storage in gigabytes.
+* `engine` - (Required unless a `snapshot_identifier` or `replicate_source_db` is provided) The database engine to use.
 * `engine_version` - (Optional) The engine version to use.
 * `identifier` - (Required) The name of the RDS instance
 * `instance_class` - (Required) The instance type of the RDS instance.
@@ -65,9 +65,9 @@ the final snapshot (if `final_snapshot_identifier` is specified). Default
 `false`
 * `name` - (Optional) The DB name to create. If omitted, no database is created
     initially.
-* `password` - (Required) Password for the master DB user. Note that this may
+* `password` - (Required unless a `snapshot_identifier` or `replicate_source_db` is provided) Password for the master DB user. Note that this may
     show up in logs, and it will be stored in the state file.
-* `username` - (Required) Username for the master DB user.
+* `username` - (Required unless a `snapshot_identifier` or `replicate_source_db` is provided) Username for the master DB user.
 * `availability_zone` - (Optional) The AZ for the RDS instance.
 * `backup_retention_period` - (Optional) The days to retain backups for. Must be
 `1` or greater to be a source for a [Read Replica][1].