feat: Enable passing admin username for Postgres

aws-postgresql.yml

@@ -330,6 +330,11 @@ provision:
       If you do, the encryption is done using an AWS KMS customer managed key.
       This property if provided, will set the customer managed key to use for encrypting the Cloudwatch log group
       created for the RDS PostgreSQL and upgrade logs.
+  - field_name: admin_username
+    type: string
+    details: The username to use for the admin user of the database. When not specified a random username will be generated. This property should only be used when migrating data.
+    default: ""
+    prohibit_update: true
   computed_inputs:
   - name: labels
     default: ${json.marshal(request.default_labels)}

integration-tests/postgresql_test.go

@@ -214,6 +214,7 @@ var _ = Describe("Postgresql", Label("Postgresql"), func() {
 				"enable_export_upgrade_logs":                        true,
 				"cloudwatch_upgrade_log_group_retention_in_days":    1,
 				"cloudwatch_log_groups_kms_key_id":                  "arn:aws:kms:us-west-2:xxxxxxxxxxxx:key/xxxxxxxx-80b9-4afd-98c0-xxxxxxxxxxxx",
+				"admin_username":                                    "some-other-username",
 			})
 			Expect(err).NotTo(HaveOccurred())
 
@@ -255,6 +256,7 @@ var _ = Describe("Postgresql", Label("Postgresql"), func() {
 					HaveKeyWithValue("enable_export_upgrade_logs", true),
 					HaveKeyWithValue("cloudwatch_upgrade_log_group_retention_in_days", BeNumerically("==", 1)),
 					HaveKeyWithValue("cloudwatch_log_groups_kms_key_id", "arn:aws:kms:us-west-2:xxxxxxxxxxxx:key/xxxxxxxx-80b9-4afd-98c0-xxxxxxxxxxxx"),
+					HaveKeyWithValue("admin_username", "some-other-username"),
 				),
 			)
 		})
@@ -301,6 +303,7 @@ var _ = Describe("Postgresql", Label("Postgresql"), func() {
 				const initialProvisionInvocation = 1
 				Expect(mockTerraform.ApplyInvocations()).To(HaveLen(initialProvisionInvocation))
 			},
+			Entry("admin_username", "admin_username", "new-username"),
 			Entry("update region", "region", "no-matter-what-region"),
 			Entry("update kms_key_id", "kms_key_id", "no-matter-what-key"),
 			Entry("update db_name", "db_name", "no-matter-what-name"),

terraform-tests/postgres_test.go

@@ -67,6 +67,7 @@ var _ = Describe("postgres", Label("postgres-terraform"), Ordered, func() {
 			"enable_export_upgrade_logs":                        false,
 			"cloudwatch_upgrade_log_group_retention_in_days":    30,
 			"cloudwatch_log_groups_kms_key_id":                  "",
+			"admin_username":                                    "",
 		}
 	})
 
@@ -75,6 +76,50 @@ var _ = Describe("postgres", Label("postgres-terraform"), Ordered, func() {
 		Init(terraformProvisionDir)
 	})
 
+	Context("admin username", func() {
+		When("admin username has been passed", func() {
+			BeforeAll(func() {
+				plan = ShowPlan(terraformProvisionDir, buildVars(defaultVars, map[string]any{
+					"admin_username": "test-name",
+				}))
+			})
+
+			It("should use that admin username", func() {
+				Expect(ResourceChangesTypes(plan)).To(ConsistOf(
+					"aws_db_instance",
+					"random_password",
+					"aws_db_parameter_group",
+					"aws_db_subnet_group",
+					"aws_security_group",
+					"aws_security_group_rule",
+				))
+
+				Expect(AfterValuesForType(plan, "aws_db_instance")).To(
+					MatchKeys(IgnoreExtras, Keys{
+						"username": Equal("test-name"),
+					}))
+			})
+		})
+
+		When("admin username has not been passed", func() {
+			BeforeAll(func() {
+				plan = ShowPlan(terraformProvisionDir, buildVars(defaultVars, map[string]any{}))
+			})
+
+			It("should create a new random admin username", func() {
+				Expect(ResourceChangesTypes(plan)).To(ConsistOf(
+					"aws_db_instance",
+					"random_password",
+					"random_string",
+					"aws_db_parameter_group",
+					"aws_db_subnet_group",
+					"aws_security_group",
+					"aws_security_group_rule",
+				))
+			})
+		})
+	})
+
 	Context("cloud watch log groups", func() {
 		When("no parameters passed", func() {
 			BeforeAll(func() {

terraform/postgresql/provision/main.tf

@@ -38,6 +38,7 @@ resource "random_string" "username" {
   length  = 16
   special = false
   numeric = false
+  count   = length(var.admin_username) == 0 ? 1 : 0
 }
 
 resource "random_password" "password" {
@@ -57,7 +58,7 @@ resource "aws_db_instance" "db_instance" {
   instance_class                        = local.instance_class
   identifier                            = var.instance_name
   db_name                               = var.db_name
-  username                              = random_string.username.result
+  username                              = length(var.admin_username) == 0 ? random_string.username[0].result : var.admin_username
   password                              = random_password.password.result
   parameter_group_name                  = length(var.parameter_group_name) == 0 ? aws_db_parameter_group.db_parameter_group[0].name : var.parameter_group_name
   tags                                  = var.labels

terraform/postgresql/provision/variables.tf

@@ -63,4 +63,5 @@ variable "enable_export_postgresql_logs" { type = bool }
 variable "enable_export_upgrade_logs" { type = bool }
 variable "cloudwatch_postgresql_log_group_retention_in_days" { type = number }
 variable "cloudwatch_upgrade_log_group_retention_in_days" { type = number }
-variable "cloudwatch_log_groups_kms_key_id" { type = string }
+variable "cloudwatch_log_groups_kms_key_id" { type = string }
+variable "admin_username" { type = string }