Add datasource, aka "connection string", option to sqlserverreceiver (open-telemetry#39235)

#### Description
Adds an option, `datasource`, that allows full control of the connection
string used when connecting to the DB. There are many possible
variations that are useful that can be specified via this option, e.g.:
one could enable Windows authentication and have the collector run with
an account configured to access the SQL server.

#### Testing
Covered the new option in an extended validation test and used it to
connect to a SQL server using Windows credentials.

#### Documentation
Added a note about the new option.

---------

Co-authored-by: Antoine Toulme <[email protected]>

Author: 2 people

.chloggen/receiver-sqlserverreceiver-datasource.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: sqlserverreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Allow full control of the "connection string" via the `datasource` configuration option
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [39235]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

receiver/sqlserverreceiver/README.md

@@ -34,6 +34,9 @@ Direct connection options (optional, but all must be specified to enable):
 - `server`: IP Address or hostname of SQL Server instance to connect to.
 - `port`: Port of the SQL Server instance to connect to.
 
+For finer control over the direct connection use the `datasource`, a.k.a. the "connection string", instead.
+Note: it can't be used in conjunction with the `username`, `password`, `server` and `port` options.
+
 Windows-specific options:
 - `computer_name` (optional): The computer name identifies the SQL Server name or IP address of the computer being monitored.
   If specified, `instance_name` is also required to be defined. This option is ignored in non-Windows environments.

receiver/sqlserverreceiver/config.go

@@ -45,11 +45,16 @@ type Config struct {
 	InstanceName string `mapstructure:"instance_name"`
 	ComputerName string `mapstructure:"computer_name"`
 
-	// The following options currently do nothing. Functionality will be added in a future PR.
+	DataSource string `mapstructure:"datasource"`
+
 	Password configopaque.String `mapstructure:"password"`
 	Port     uint                `mapstructure:"port"`
 	Server   string              `mapstructure:"server"`
 	Username string              `mapstructure:"username"`
+
+	// Flag to check if the connection is direct or not. It should only be
+	// used after a successful call to the `Validate` method.
+	isDirectDBConnectionEnabled bool
 }
 
 func (cfg *Config) Validate() error {
@@ -66,12 +71,27 @@ func (cfg *Config) Validate() error {
 		return errors.New("`top_query_count` must be less than or equal to `max_query_sample_count`")
 	}
 
-	if !directDBConnectionEnabled(cfg) {
-		if cfg.Server != "" || cfg.Username != "" || string(cfg.Password) != "" {
-			return errors.New("Found one or more of the following configuration options set: [server, port, username, password]. " +
-				"All of these options must be configured to directly connect to a SQL Server instance.")
-		}
+	cfg.isDirectDBConnectionEnabled, err = directDBConnectionEnabled(cfg)
+
+	return err
+}
+
+func directDBConnectionEnabled(config *Config) (bool, error) {
+	noneOfServerUserPasswordPortSet := config.Server == "" && config.Username == "" && string(config.Password) == "" && config.Port == 0
+	if config.DataSource == "" && noneOfServerUserPasswordPortSet {
+		// If no connection information is provided, we can't connect directly and this is a valid config.
+		return false, nil
+	}
+
+	anyOfServerUserPasswordPortSet := config.Server != "" || config.Username != "" || string(config.Password) != "" || config.Port != 0
+	if config.DataSource != "" && anyOfServerUserPasswordPortSet {
+		return false, errors.New("wrong config: when specifying 'datasource' no other connection parameters ('server', 'username', 'password', or 'port') should be set")
+	}
+
+	if config.DataSource == "" && (config.Server == "" || config.Username == "" || string(config.Password) == "" || config.Port == 0) {
+		return false, errors.New("wrong config: when specifying either 'server', 'username', 'password', or 'port' all of them need to be specified")
 	}
 
-	return nil
+	// It is a valid direct connection configuration
+	return true, nil
 }

receiver/sqlserverreceiver/config_test.go

@@ -53,6 +53,24 @@ func TestValidate(t *testing.T) {
 			},
 			expectedSuccess: false,
 		},
+		{
+			desc: "invalid config with datasource and any direct connect settings",
+			cfg: &Config{
+				ControllerConfig: scraperhelper.NewDefaultControllerConfig(),
+				DataSource:       "a connection string",
+				Username:         "sa",
+				Port:             1433,
+			},
+			expectedSuccess: false,
+		},
+		{
+			desc: "valid config only datasource and none direct connect settings",
+			cfg: &Config{
+				ControllerConfig: scraperhelper.NewDefaultControllerConfig(),
+				DataSource:       "a connection string",
+			},
+			expectedSuccess: true,
+		},
 		{
 			desc: "valid config with all direct connection settings",
 			cfg: &Config{
@@ -160,7 +178,7 @@ func TestLoadConfig(t *testing.T) {
 		require.NoError(t, sub.Unmarshal(cfg))
 
 		assert.NoError(t, xconfmap.Validate(cfg))
-		if diff := cmp.Diff(expected, cfg, cmpopts.IgnoreUnexported(metadata.MetricConfig{}), cmpopts.IgnoreUnexported(metadata.ResourceAttributeConfig{})); diff != "" {
+		if diff := cmp.Diff(expected, cfg, cmpopts.IgnoreUnexported(Config{}), cmpopts.IgnoreUnexported(metadata.MetricConfig{}), cmpopts.IgnoreUnexported(metadata.ResourceAttributeConfig{})); diff != "" {
 			t.Errorf("Config mismatch (-expected +actual):\n%s", diff)
 		}
 	})

receiver/sqlserverreceiver/factory.go

@@ -94,20 +94,17 @@ func setupLogQueries(cfg *Config) []string {
 	return queries
 }
 
-func directDBConnectionEnabled(config *Config) bool {
-	return config.Server != "" &&
-		config.Username != "" &&
-		string(config.Password) != ""
-}
-
 // Assumes config has all information necessary to directly connect to the database
 func getDBConnectionString(config *Config) string {
+	if config.DataSource != "" {
+		return config.DataSource
+	}
 	return fmt.Sprintf("server=%s;user id=%s;password=%s;port=%d", config.Server, config.Username, string(config.Password), config.Port)
 }
 
 // SQL Server scraper creation is split out into a separate method for the sake of testing.
 func setupSQLServerScrapers(params receiver.Settings, cfg *Config) []*sqlServerScraperHelper {
-	if !directDBConnectionEnabled(cfg) {
+	if !cfg.isDirectDBConnectionEnabled {
 		params.Logger.Info("No direct connection will be made to the SQL Server: Configuration doesn't include some options.")
 		return nil
 	}
@@ -147,7 +144,7 @@ func setupSQLServerScrapers(params receiver.Settings, cfg *Config) []*sqlServerS
 
 // SQL Server scraper creation is split out into a separate method for the sake of testing.
 func setupSQLServerLogsScrapers(params receiver.Settings, cfg *Config) []*sqlServerScraperHelper {
-	if !directDBConnectionEnabled(cfg) {
+	if !cfg.isDirectDBConnectionEnabled {
 		params.Logger.Info("No direct connection will be made to the SQL Server: Configuration doesn't include some options.")
 		return nil
 	}

receiver/sqlserverreceiver/factory_others_test.go

@@ -35,7 +35,7 @@ func TestFactoryOtherOS(t *testing.T) {
 				cfg.Metrics.SqlserverDatabaseLatency.Enabled = true
 				require.NoError(t, cfg.Validate())
 
-				require.True(t, directDBConnectionEnabled(cfg))
+				require.True(t, cfg.isDirectDBConnectionEnabled)
 				require.Equal(t, "server=0.0.0.0;user id=sa;password=password;port=1433", getDBConnectionString(cfg))
 
 				params := receivertest.NewNopSettings(metadata.Type)
@@ -78,7 +78,7 @@ func TestFactoryOtherOS(t *testing.T) {
 				cfg.Port = 1433
 				require.NoError(t, cfg.Validate())
 
-				require.True(t, directDBConnectionEnabled(cfg))
+				require.True(t, cfg.isDirectDBConnectionEnabled)
 				require.Equal(t, "server=0.0.0.0;user id=sa;password=password;port=1433", getDBConnectionString(cfg))
 
 				params := receivertest.NewNopSettings(metadata.Type)

receiver/sqlserverreceiver/factory_test.go

@@ -102,7 +102,7 @@ func TestFactory(t *testing.T) {
 				require.NoError(t, cfg.Validate())
 				cfg.Metrics.SqlserverDatabaseLatency.Enabled = true
 
-				require.True(t, directDBConnectionEnabled(cfg))
+				require.True(t, cfg.isDirectDBConnectionEnabled)
 				require.Equal(t, "server=0.0.0.0;user id=sa;password=password;port=1433", getDBConnectionString(cfg))
 
 				params := receivertest.NewNopSettings(metadata.Type)
@@ -190,7 +190,7 @@ func TestFactory(t *testing.T) {
 				require.NoError(t, cfg.Validate())
 				cfg.Metrics.SqlserverDatabaseLatency.Enabled = true
 
-				require.True(t, directDBConnectionEnabled(cfg))
+				require.True(t, cfg.isDirectDBConnectionEnabled)
 				require.Equal(t, "server=0.0.0.0;user id=sa;password=password;port=1433", getDBConnectionString(cfg))
 
 				params := receivertest.NewNopSettings(metadata.Type)