Add sql_driver data source

Fixes #14

docs/data-sources/driver.md

@@ -0,0 +1,23 @@
+---
+# generated by https://github.com/hashicorp/terraform-plugin-docs
+page_title: "sql_driver Data Source - terraform-provider-sql"
+subcategory: ""
+description: |-
+  The sql_driver datasource allows you to determine which driver is in use by the provider. This is mostly useful for module development when you may communicate with multiple types of databases.
+---
+
+# sql_driver (Data Source)
+
+The `sql_driver` datasource allows you to determine which driver is in use by the provider. This is mostly useful for module development when you may communicate with multiple types of databases.
+
+
+
+<!-- schema generated by tfplugindocs -->
+## Schema
+
+### Read-Only
+
+- **id** (String, Deprecated) This attribute is only present for some compatibility issues and should not be used. It will be removed in a future version.
+- **name** (String) The name of the driver, currently this will be one of `pgx`, `mysql`, or `sqlserver`.
+
+

docs/data-sources/query.md

@@ -6,7 +6,7 @@ description: |-
   The sql_query datasource allows you to execute a SQL query against the database of your choice.
 ---
 
-# Data Source `sql_query`
+# sql_query (Data Source)
 
 The `sql_query` datasource allows you to execute a SQL query against the database of your choice.
 
@@ -35,7 +35,7 @@ output "math" {
 
 - **query** (String) The query to execute. The types in this query will be reflected in the typing of the `result` attribute.
 
-### Read-only
+### Read-Only
 
 - **id** (String, Deprecated) This attribute is only present for some compatibility issues and should not be used. It will be removed in a future version.
 - **result** (List of Dynamic) The result of the query. This will be a list of objects. Each object will have attributes with names that match column names and types that match column types. The exact translation of types is dependent upon the database driver.

docs/resources/migrate.md

@@ -6,7 +6,7 @@ description: |-
   
 ---
 
-# Resource `sql_migrate`
+# sql_migrate (Resource)
 
 
 
@@ -51,7 +51,7 @@ output "rowcount" {
 
 - **migration** (Block List) (see [below for nested schema](#nestedblock--migration))
 
-### Read-only
+### Read-Only
 
 - **complete_migrations** (List of Object) The completed migrations that have been run against your database. This list is used as storage to migrate down or as a trigger for downstream dependencies. (see [below for nested schema](#nestedatt--complete_migrations))
 - **id** (String, Deprecated) This attribute is only present for some compatibility issues and should not be used. It will be removed in a future version.
@@ -69,7 +69,7 @@ Required:
 <a id="nestedatt--complete_migrations"></a>
 ### Nested Schema for `complete_migrations`
 
-Read-only:
+Read-Only:
 
 - **down** (String)
 - **id** (String)

docs/resources/migrate_directory.md

@@ -6,7 +6,7 @@ description: |-
   
 ---
 
-# Resource `sql_migrate_directory`
+# sql_migrate_directory (Resource)
 
 
 
@@ -41,15 +41,15 @@ output "rowcount" {
 
 - **single_file_split** (String) Set this to a value if your migration up and down are in a single file, split on some constant string (ie. in the case of [shmig](https://github.com/mbucc/shmig) you would use `-- ==== DOWN ====`).
 
-### Read-only
+### Read-Only
 
 - **complete_migrations** (List of Object) The completed migrations that have been run against your database. This list is used as storage to migrate down or as a trigger for downstream dependencies. (see [below for nested schema](#nestedatt--complete_migrations))
 - **id** (String, Deprecated) This attribute is only present for some compatibility issues and should not be used. It will be removed in a future version.
 
 <a id="nestedatt--complete_migrations"></a>
 ### Nested Schema for `complete_migrations`
 
-Read-only:
+Read-Only:
 
 - **down** (String)
 - **id** (String)

internal/provider/data_driver.go

@@ -0,0 +1,61 @@
+package provider
+
+import (
+	"context"
+
+	"github.com/hashicorp/terraform-plugin-go/tfprotov5"
+	"github.com/hashicorp/terraform-plugin-go/tfprotov5/tftypes"
+	"github.com/paultyng/terraform-provider-sql/internal/server"
+)
+
+type dataDriver struct {
+	driver string
+}
+
+var _ server.DataSource = (*dataDriver)(nil)
+
+func newDataDriver(driver driverName) (*dataDriver, error) {
+	return &dataDriver{
+		driver: string(driver),
+	}, nil
+}
+
+func (d *dataDriver) Schema(context.Context) *tfprotov5.Schema {
+	return &tfprotov5.Schema{
+		Block: &tfprotov5.SchemaBlock{
+			Description: "The `sql_driver` datasource allows you to determine which driver is in use by the provider. This " +
+				"is mostly useful for module development when you may communicate with multiple types of databases.",
+			DescriptionKind: tfprotov5.StringKindMarkdown,
+			Attributes: []*tfprotov5.SchemaAttribute{
+				{
+					Name:            "name",
+					Computed:        true,
+					Description:     "The name of the driver, currently this will be one of `pgx`, `mysql`, or `sqlserver`.",
+					DescriptionKind: tfprotov5.StringKindMarkdown,
+					Type:            tftypes.String,
+				},
+
+				deprecatedIDAttribute(),
+			},
+		},
+	}
+}
+
+func (d *dataDriver) Validate(ctx context.Context, config map[string]tftypes.Value) ([]*tfprotov5.Diagnostic, error) {
+	return nil, nil
+}
+
+func (d *dataDriver) Read(ctx context.Context, config map[string]tftypes.Value) (map[string]tftypes.Value, []*tfprotov5.Diagnostic, error) {
+	return map[string]tftypes.Value{
+		"name": tftypes.NewValue(
+			tftypes.String,
+			d.driver,
+		),
+
+		// just a placeholder, see deprecatedIDAttribute
+		"id": tftypes.NewValue(
+			tftypes.String,
+			"",
+		),
+	}, nil, nil
+}

internal/provider/data_driver_test.go

@@ -0,0 +1,54 @@
+package provider
+
+import (
+	"fmt"
+	"testing"
+
+	helperresource "github.com/hashicorp/terraform-plugin-sdk/v2/helper/resource"
+	"github.com/hashicorp/terraform-plugin-sdk/v2/terraform"
+)
+
+func TestDataDriver(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping long test")
+	}
+
+	for _, server := range testServers {
+		// TODO: check nulls for all these
+		t.Run(server.ServerType, func(t *testing.T) {
+			url, _, err := server.URL()
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			helperresource.UnitTest(t, helperresource.TestCase{
+				ProtoV5ProviderFactories: protoV5ProviderFactories,
+				Steps: []helperresource.TestStep{
+					{
+
+						Config: fmt.Sprintf(`
+provider "sql" {
+url = %q
+
+max_idle_conns = 0
+}
+
+data "sql_driver" "test" {
+}
+		`, url),
+						Check: helperresource.ComposeTestCheckFunc(
+							func(s *terraform.State) error {
+								rs := s.RootModule().Resources["data.sql_driver.test"]
+								att := rs.Primary.Attributes["name"]
+								if att != server.ExpectedDriver {
+									return fmt.Errorf("expected %q, got %q", server.ExpectedDriver, att)
+								}
+								return nil
+							},
+						),
+					},
+				},
+			})
+		})
+	}
+}

internal/provider/db.go

@@ -37,6 +37,7 @@ func (p *provider) connect(dsn string) error {
 
 	switch scheme {
 	case "postgres", "postgresql":
+		// TODO: use consts for these driver names?
 		p.Driver = "pgx"
 	case "mysql":
 		p.Driver = "mysql"
@@ -51,7 +52,7 @@ func (p *provider) connect(dsn string) error {
 		return fmt.Errorf("unexpected datasource name scheme: %q", scheme)
 	}
 
-	p.DB, err = sql.Open(p.Driver, dsn)
+	p.DB, err = sql.Open(string(p.Driver), dsn)
 	if err != nil {
 		return fmt.Errorf("unable to open database: %w", err)
 	}

internal/provider/db_test.go

@@ -33,6 +33,8 @@ var testServers = []*testServer{
 
 			return resource, url, nil
 		},
+
+		ExpectedDriver: "mysql",
 	},
 	{
 		ServerType: "postgres",
@@ -51,6 +53,8 @@ var testServers = []*testServer{
 
 			return resource, url, nil
 		},
+
+		ExpectedDriver: "pgx",
 	},
 	{
 		ServerType: "cockroach",
@@ -78,6 +82,8 @@ var testServers = []*testServer{
 			}
 			return nil
 		},
+
+		ExpectedDriver: "pgx",
 	},
 	{
 		ServerType: "sqlserver",
@@ -95,6 +101,8 @@ var testServers = []*testServer{
 
 			return resource, url, nil
 		},
+
+		ExpectedDriver: "sqlserver",
 	},
 }
 
@@ -167,6 +175,9 @@ type testServer struct {
 	StartContainer func() (*dockertest.Resource, string, error)
 	OnReady        func(*sql.DB) error
 
+	// This is the driver determination expected by the URL scheme
+	ExpectedDriver string
+
 	// these are all governed by the sync.Once
 	// TODO: support multiple instances, so one test doesn't break
 	// another, etc. or maybe just multiple databases in a single server?

internal/provider/provider.go

@@ -20,6 +20,7 @@ func New(version string) func() tfprotov5.ProviderServer {
 		})
 
 		// data sources
+		s.MustRegisterDataSource("sql_driver", newDataDriver)
 		s.MustRegisterDataSource("sql_query", newDataQuery)
 
 		// resources
@@ -30,10 +31,13 @@ func New(version string) func() tfprotov5.ProviderServer {
 	}
 }
 
+// TODO: use consts for driver names?
+type driverName string
+
 type provider struct {
 	DB *sql.DB `argmapper:",typeOnly"`
 
-	Driver string
+	Driver driverName
 }
 
 var _ server.Provider = (*provider)(nil)