Add aws_db_instances data source

.changelog/28303.txt

@@ -0,0 +1,3 @@
+```release-note:new-data-source
+aws_db_instances
+```

internal/provider/provider.go

@@ -837,6 +837,7 @@ func New(_ context.Context) (*schema.Provider, error) {
 			"aws_db_cluster_snapshot":            rds.DataSourceClusterSnapshot(),
 			"aws_db_event_categories":            rds.DataSourceEventCategories(),
 			"aws_db_instance":                    rds.DataSourceInstance(),
+			"aws_db_instances":                   rds.DataSourceInstances(),
 			"aws_db_proxy":                       rds.DataSourceProxy(),
 			"aws_db_snapshot":                    rds.DataSourceSnapshot(),
 			"aws_db_subnet_group":                rds.DataSourceSubnetGroup(),

internal/service/rds/instances_data_source.go

@@ -0,0 +1,78 @@
+package rds
+
+import (
+	"context"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/service/rds"
+	"github.com/hashicorp/terraform-plugin-sdk/v2/diag"
+	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
+	"github.com/hashicorp/terraform-provider-aws/internal/conns"
+	"github.com/hashicorp/terraform-provider-aws/internal/create"
+	"github.com/hashicorp/terraform-provider-aws/internal/generate/namevaluesfilters"
+	"github.com/hashicorp/terraform-provider-aws/names"
+)
+
+func DataSourceInstances() *schema.Resource {
+	return &schema.Resource{
+		ReadWithoutTimeout: dataSourceInstancesRead,
+
+		Schema: map[string]*schema.Schema{
+			"instance_arns": {
+				Type:     schema.TypeList,
+				Computed: true,
+				Elem:     &schema.Schema{Type: schema.TypeString},
+			},
+			"instance_identifiers": {
+				Type:     schema.TypeList,
+				Computed: true,
+				Elem:     &schema.Schema{Type: schema.TypeString},
+			},
+			"filter": namevaluesfilters.Schema(),
+		},
+	}
+}
+
+const (
+	DSNameInstances = "Instances Data Source"
+)
+
+func dataSourceInstancesRead(ctx context.Context, d *schema.ResourceData, meta interface{}) diag.Diagnostics {
+	conn := meta.(*conns.AWSClient).RDSConn
+
+	input := &rds.DescribeDBInstancesInput{}
+
+	if v, ok := d.GetOk("filter"); ok {
+		input.Filters = namevaluesfilters.New(v.(*schema.Set)).RDSFilters()
+	}
+
+	var instanceARNS []string
+	var instanceIdentifiers []string
+
+	err := conn.DescribeDBInstancesPagesWithContext(ctx, input, func(page *rds.DescribeDBInstancesOutput, lastPage bool) bool {
+		if page == nil {
+			return !lastPage
+		}
+
+		for _, dbInstance := range page.DBInstances {
+			if dbInstance == nil {
+				continue
+			}
+
+			instanceARNS = append(instanceARNS, aws.StringValue(dbInstance.DBInstanceArn))
+			instanceIdentifiers = append(instanceIdentifiers, aws.StringValue(dbInstance.DBInstanceIdentifier))
+		}
+
+		return !lastPage
+	})
+
+	if err != nil {
+		return create.DiagError(names.RDS, create.ErrActionReading, DSNameInstances, "", err)
+	}
+
+	d.SetId(meta.(*conns.AWSClient).Region)
+	d.Set("instance_arns", instanceARNS)
+	d.Set("instance_identifiers", instanceIdentifiers)
+
+	return nil
+}

internal/service/rds/instances_data_source_test.go

@@ -0,0 +1,83 @@
+package rds_test
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/aws/aws-sdk-go/service/rds"
+	sdkacctest "github.com/hashicorp/terraform-plugin-sdk/v2/helper/acctest"
+	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/resource"
+	"github.com/hashicorp/terraform-provider-aws/internal/acctest"
+)
+
+func TestAccRDSInstancesDataSource_filter(t *testing.T) {
+	var dbInstance rds.DBInstance
+	rName := sdkacctest.RandomWithPrefix(acctest.ResourcePrefix)
+	dataSourceName := "data.aws_db_instances.test"
+	resourceName := "aws_db_instance.test"
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:                 func() { acctest.PreCheck(t) },
+		ErrorCheck:               acctest.ErrorCheck(t, rds.EndpointsID),
+		ProtoV5ProviderFactories: acctest.ProtoV5ProviderFactories,
+		CheckDestroy:             testAccCheckInstanceDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccInstancesDataSourceConfig_filter(rName),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckInstanceExists(resourceName, &dbInstance),
+					resource.TestCheckResourceAttr(dataSourceName, "instance_arns.#", "1"),
+					resource.TestCheckResourceAttrPair(dataSourceName, "instance_arns.0", resourceName, "arn"),
+					resource.TestCheckResourceAttr(dataSourceName, "instance_identifiers.#", "1"),
+					resource.TestCheckResourceAttrPair(dataSourceName, "instance_identifiers.0", resourceName, "identifier"),
+				),
+			},
+		},
+	})
+}
+
+func testAccInstancesDataSourceConfig_filter(rName string) string {
+	return fmt.Sprintf(`
+data "aws_rds_engine_version" "default" {
+  engine = "postgres"
+}
+
+resource "aws_db_instance" "test" {
+  identifier           = %[1]q
+  allocated_storage    = 10
+  engine               = data.aws_rds_engine_version.default.engine
+  engine_version       = data.aws_rds_engine_version.default.version
+  instance_class       = "db.t4g.micro"
+  db_name              = "test"
+  password             = "avoid-plaintext-passwords"
+  username             = "tfacctest"
+  parameter_group_name = "default.${data.aws_rds_engine_version.default.parameter_group_family}"
+  skip_final_snapshot  = true
+
+  apply_immediately = true
+}
+
+resource "aws_db_instance" "wrong" {
+  identifier           = "wrong-%[1]s"
+  allocated_storage    = 10
+  engine               = data.aws_rds_engine_version.default.engine
+  engine_version       = data.aws_rds_engine_version.default.version
+  instance_class       = "db.t4g.micro"
+  db_name              = "test"
+  password             = "avoid-plaintext-passwords"
+  username             = "tfacctest"
+  parameter_group_name = "default.${data.aws_rds_engine_version.default.parameter_group_family}"
+  skip_final_snapshot  = true
+
+  apply_immediately = true
+}
+
+
+data "aws_db_instances" "test" {
+  filter {
+    name   = "db-instance-id"
+    values = [aws_db_instance.test.identifier]
+  }
+}
+`, rName)
+}

website/docs/d/db_instances.html.markdown

@@ -0,0 +1,44 @@
+---
+subcategory: "RDS (Relational Database)"
+layout: "aws"
+page_title: "AWS: aws_db_instances"
+description: |-
+  Terraform data source for listing RDS Database Instances.
+---
+
+# Data Source: aws_db_instances
+
+Terraform data source for listing RDS Database Instances.
+
+## Example Usage
+
+### Basic Usage
+
+```terraform
+data "aws_db_instances" "example" {
+  filter {
+    name   = "db-instance-id"
+    values = ["my-database-id"]
+  }
+}
+```
+
+## Argument Reference
+
+The following arguments are optional:
+
+* `filter` - (Optional) Configuration block(s) for filtering. Detailed below.
+
+### filter Configuration block
+
+The following arguments are supported by the `filter` configuration block:
+
+* `name` - (Required) Name of the filter field. Valid values can be found in the [RDS DescribeDBClusters API Reference](https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_DescribeDBClusters.html).
+* `values` - (Required) Set of values that are accepted for the given filter field. Results will be selected if any given value matches.
+
+## Attributes Reference
+
+In addition to all arguments above, the following attributes are exported:
+
+* `instance_arns` - ARNs of the matched RDS instances.
+* `instance_identifiers` - Identifiers of the matched RDS instances.