[MySQL] Add connection attribute example for Go

See
- Pull Request: go-sql-driver/mysql#1389
- Release: https://github.com/go-sql-driver/mysql/releases/tag/v1.8.0

mysql/README.md

@@ -8,7 +8,7 @@ Programmming languages:
 
 - [Python (with PyMySQL)](./python-PyMySQL)
 - [Python (with mysql-connector-python)](./python-mysql-connector-python)
-- Go: Not supported yet, see [Support for sending connection attributes #737 @ go-sql-driver/mysql](https://github.com/go-sql-driver/mysql/pull/737)
+- [Go](./go)
 - PHP: Not supported yet, see [Add possibility to add MySQL Connection Attributes (incl. custom ones) @ PHP Bugtracker](https://bugs.php.net/bug.php?id=81314)
 
 ## How it works

mysql/go/README.md

@@ -0,0 +1,74 @@
+![MySQL logo](../../images/mysql-logo.png)
+
+# your _MySQL_ connection deserves a name: Go edition (with github.com/go-sql-driver/mysql)
+
+An example on how to assign a name to a [MySQL](https://www.mysql.com/) connection in Go.
+
+## Get it running
+
+1. Start the MySQL docker container:
+```sh
+$ docker run --rm \
+    --publish 3306:3306 \
+    --env MYSQL_ROOT_PASSWORD=secret \
+    --env MYSQL_DATABASE=dummy \
+    --name ycdan-mysql \
+    --detach \
+    mysql:8.0.36 mysqld --default-authentication-plugin=mysql_native_password
+```
+
+2. Compile the example program:
+```sh
+$ go build -o your-connection-deserves-a-name
+```
+
+3. Start the example program:
+```sh
+$ ./your-connection-deserves-a-name
+```
+
+You should see something like
+
+```
+2024/03/17 09:04:05 Connecting to MySQL on root:secret@tcp(127.0.0.1:3306)/dummy?connectionAttributes=program_name:currency-conversion-app
+2024/03/17 09:04:05 Connecting to MySQL on root:secret@tcp(127.0.0.1:3306)/dummy?connectionAttributes=program_name:currency-conversion-app ... Successful
+2024/03/17 09:04:05
+2024/03/17 09:04:05 Keeping the connection open ...
+2024/03/17 09:04:05 You can connect to the MySQL database and execute the query:
+2024/03/17 09:04:05 	SELECT
+2024/03/17 09:04:05 	    session_connect_attrs.ATTR_VALUE AS program_name,
+2024/03/17 09:04:05 	    processlist.*
+2024/03/17 09:04:05 	FROM information_schema.processlist
+2024/03/17 09:04:05 	LEFT JOIN  performance_schema.session_connect_attrs ON (
+2024/03/17 09:04:05 	    processlist.ID = session_connect_attrs.PROCESSLIST_ID
+2024/03/17 09:04:05 	    AND session_connect_attrs.ATTR_NAME = "program_name"
+2024/03/17 09:04:05 	)
+2024/03/17 09:04:05 Hit CTRL + C or cancel the process to stop.
+2024/03/17 09:04:05
+```
+
+4. Login into your database and execute the query:
+```sql
+SELECT
+    session_connect_attrs.ATTR_VALUE AS program_name,
+    processlist.*
+FROM information_schema.processlist
+LEFT JOIN  performance_schema.session_connect_attrs ON (
+    processlist.ID = session_connect_attrs.PROCESSLIST_ID
+    AND session_connect_attrs.ATTR_NAME = "program_name"
+)
+```
+
+The result should look similar to:
+
+```
+program_name        | ID | USER | HOST             | DB    | [...]
+--------------------+----+------+------------------+-------+------
+unit-conversion-app | 11 | root | 172.17.0.1:56382 | dummy | [...]
+```
+
+## Don't know what this is all about?
+
+Read the original blog post [_your database connection deserves a name @ andygrunwald.com_](https://andygrunwald.com/blog/your-database-connection-deserves-a-name/ "Article your database connection deserves a name at Andy Grunwalds blog").
+
+Additionally, you can check out the [projects README](https://github.com/andygrunwald/your-connection-deserves-a-name#readme).

mysql/go/go.mod

@@ -0,0 +1,8 @@
+module github.com/andygrunwald/your-connection-deserves-a-name/mysql/go
+
+go 1.22.1
+
+require (
+	filippo.io/edwards25519 v1.1.0 // indirect
+	github.com/go-sql-driver/mysql v1.8.0 // indirect
+)

mysql/go/go.sum

@@ -0,0 +1,4 @@
+filippo.io/edwards25519 v1.1.0 h1:FNf4tywRC1HmFuKW5xopWpigGjJKiJSV0Cqo0cJWDaA=
+filippo.io/edwards25519 v1.1.0/go.mod h1:BxyFTGdWcka3PhytdK4V28tE5sGfRvvvRV7EaN4VDT4=
+github.com/go-sql-driver/mysql v1.8.0 h1:UtktXaU2Nb64z/pLiGIxY4431SJ4/dR5cjMmlVHgnT4=
+github.com/go-sql-driver/mysql v1.8.0/go.mod h1:wEBSXgmK//2ZFJyE+qWnIsVGmvmEKlqwuVSjsCm7DZg=

mysql/go/main.go

@@ -0,0 +1,86 @@
+package main
+
+import (
+	"database/sql"
+	"fmt"
+	"log"
+	"net/url"
+	"time"
+
+	_ "github.com/go-sql-driver/mysql"
+)
+
+const (
+	MySQLUsername           = "root"
+	MySQLPassword           = "secret"
+	MySQLHostname           = "127.0.0.1"
+	MySQLPort               = 3306
+	MySQLDatabase           = "dummy"
+	ConnectionAttributeName = "program_name"
+	ConnectionName          = "currency-conversion-app"
+)
+
+func main() {
+	// Doing all the magic: Setting a proper connection/application name.
+	//
+	// Connection attributes are key-value pairs that application programs can pass to the server at connect time.
+	// This property can be added to the connection string.
+	//
+	// The application name will be maintained in the `session_connect_attrs` table of your MySQL-Server.
+	//
+	// MySQL docs:
+	//	- Performance Schema Connection Attribute Tables: https://dev.mysql.com/doc/refman/8.0/en/performance-schema-connection-attribute-tables.html
+	//	- Connection Attribute Limits: https://dev.mysql.com/doc/refman/8.0/en/performance-schema-connection-attribute-tables.html#performance-schema-connection-attribute-limits
+
+	dsn := fmt.Sprintf("%s@tcp(%s:%d)/%s?connectionAttributes=%s:%s", url.UserPassword(MySQLUsername, MySQLPassword), MySQLHostname, MySQLPort, MySQLDatabase, ConnectionAttributeName, ConnectionName)
+
+	// Building the connection
+	log.Printf("Connecting to MySQL on %s\n", dsn)
+	client, err := sql.Open("mysql", dsn)
+	if err != nil {
+		panic(err)
+	}
+	defer func() {
+		if err = client.Close(); err != nil {
+			panic(err)
+		}
+	}()
+
+	// Dummy values for demo purpose
+	client.SetConnMaxLifetime(time.Minute * 3)
+	client.SetMaxOpenConns(10)
+	client.SetMaxIdleConns(10)
+
+	// Establish the connection, because depending on the DB driver, we might only
+	// validate the credentials, but don't built up a connection.
+	err = client.Ping()
+	if err != nil {
+		panic(err)
+	}
+	log.Printf("Connecting to MySQL on %s ... Successful\n", dsn)
+
+	log.Println("")
+	log.Println("Keeping the connection open ...")
+	log.Println("You can connect to the MySQL database and execute the query:")
+	log.Println("	SELECT")
+	log.Println("	    session_connect_attrs.ATTR_VALUE AS program_name,")
+	log.Println("	    processlist.*")
+	log.Println("	FROM information_schema.processlist")
+	log.Println("	LEFT JOIN  performance_schema.session_connect_attrs ON (")
+	log.Println("	    processlist.ID = session_connect_attrs.PROCESSLIST_ID")
+	log.Println("	    AND session_connect_attrs.ATTR_NAME = \"program_name\"")
+	log.Println("	)")
+	log.Println("Hit CTRL + C or cancel the process to stop.")
+	log.Println("")
+
+	// Just looping to keep the process running.
+	// In detail we do not keep the connection active, but rely on the standard timeout.
+	// This way we provide time for the user to check the connection name behaviour.
+	for {
+		err = client.Ping()
+		if err != nil {
+			panic(err)
+		}
+		time.Sleep(5 * time.Second)
+	}
+}