How to obtain MongoDB version using Golang library?

I am using Go's MongodDB driver (https://pkg.go.dev/go.mongodb.org/mongo-driver@v1.8.0/mongo#section-documentation) and want to obtain the version of the mongoDB server deployed.

For instance, if it would been a MySQL database, I can do something like below:

db, err := sql.Open("mysql", DbUser+":"+DbPwd+"@tcp("+Host+")/"+DbName)
if err != nil {
	log.Printf("Error while connecting to DB: %v", err)
}
defer db.Close()

var dbVersion string
if err := db.QueryRow("SELECT VERSION()").Scan(&dbVersion); err != nil {
	dbVersion = "NA"
	log.Printf("Couldnt obtain db version: %w", err)
}
fmt.Println("DB Version: ", dbVersion)

I went through the documentation but am not able to find a clue.

I also need to fetch other metadata like Size of a particular database etc.

Any help would be appreciated. Thanks!

The MongoDB version can be acquired by running a command, specifically the buildInfo command.

Using the shell, this is how you could do it:

db.runCommand({buildInfo: 1})

The result is a document whose version property holds the server version, e.g.:

{
	"version" : "5.0.6",
    ...
}

To run commands using the official driver, use the Database.RunCommand() method.

For example:

// Connect to MongoDB and acquire a Database:

ctx := context.Background()
opts := options.Client().ApplyURI("mongodb://localhost")
client, err := mongo.Connect(ctx, opts)
if err != nil {
	log.Fatalf("Failed to connect to db: %v", err)
}
defer client.Disconnect(ctx)

db := client.Database("your-db-name")

// And now run the buildInfo command:

buildInfoCmd := bson.D{bson.E{Key: "buildInfo", Value: 1}}
var buildInfoDoc bson.M
if err := db.RunCommand(ctx, buildInfoCmd).Decode(&buildInfoDoc); err != nil {
	log.Printf("Failed to run buildInfo command: %v", err)
    return
}
log.Println("Database version:", buildInfoDoc["version"])

Based on @icza's answer, here is how to obtain other metadata of the Database:

We need to use dbStats command to obtain metadata.

host := "<your-host-name>:<pot-number>"
url := "mongodb://" + host


credential := options.Credential{
	AuthSource: "authentication-database",
	Username:   "username",
	Password:   "password",
}

clientOpts := options.Client().ApplyURI(url).SetAuth(credential)

ctx := context.Background()
client, err := mongo.Connect(ctx, clientOpts)
if err != nil {
	log.Fatal("Failed to connect to db : %w", err)
}
defer client.Disconnect(ctx)

if err := client.Ping(context.TODO(), readpref.Primary()); err != nil {
	panic(err)
}
fmt.Println("Successfully connected and pinged.")

db := client.Database("your-database-name")


dbStatsCmd := bson.D{bson.E{Key: "dbStats", Value: 1}}
var dbStatsDoc bson.M
if err := db.RunCommand(ctx, dbStatsCmd).Decode(&dbStatsDoc); err != nil {
	log.Printf("Failed to run dbStats command: %v", err)
	return
}

log.Println("\nTotal Used Size in MB: ", dbStatsDoc["totalSize"].(float64) / 1048576 , " ,Total Free size in MB (part of total used size): ", dbStatsDoc["totalFreeStorageSize"].(float64)/1048576)