How to obtain MongoDB version using Golang library? - mongodb

Question

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!

Answer 1

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"])

Answer 2

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)