Unable to ping mysql db docker in golang - mysql

Question

I am new to golang, docker and mysql. I am trying to connect to mysql running in docker locally on my macos using golang.
Here is the code:
`package main
import (
"context"
"database/sql"
_ "github.com/go-sql-driver/mysql"
"log"
"time"
)
func dbConn() *sql.DB {
db, err := sql.Open("mysql", "root:Abc123$##tcp(172.17.0.2:3306)/test")
if err != nil {
log.Printf("Error %s when opening DB connection\n", err)
return nil
}
db.SetMaxOpenConns(10)
db.SetMaxIdleConns(10)
db.SetConnMaxLifetime(time.Minute * 2)
ctx, cancelfunc := context.WithTimeout(context.Background(), time.Second)
defer cancelfunc()
err = db.PingContext(ctx)
if err != nil {
log.Printf("Error %s pinging DB", err)
return db
}
log.Print("Connected to the DB successfully\n")
defer func() {
err := db.Close()
if err != nil {
log.Print(err)
}
}()
return db
}
func main() {
db := dbConn()
defer db.Close()
}`
I am running docker with the following command:
docker run --name mysql -e MYSQL_ROOT_PASSWORD=abcd1234 -p 3306:3306 -d mysql:8.0.30
I get the following error:
Error dial tcp 172.17.0.2:3306: i/o timeout pinging DB
docker is running locally. I created a test-db with command-line:
`mysql> create database test_db;`
and then did a
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| test_db |
+--------------------+
6 rows in set (0.00 sec)
Please help me understand my mistake here? Or what am I missing?

Answer 1

I used host.docker.internal in this docker-compose.yml file to create the mysql sever in docker.
version: '3'
services:
mysql-development:
image: mysql:8.0.30
environment:
MYSQL_ROOT_PASSWORD: xyz1234
MYSQL_DATABASE: test
ports:
- "3306:3306"
extra_hosts:
- "host.docker.internal:host-gateway"
Used this to run the docker image:
docker-compose -f docker-compose.yml up
Then connected to docker mysql instance using:
docker exec -it 24f058c73227 mysql -P 3306 --protocol=tcp -u root -p
Then created a separate user and granted all privileges to the new user.
mysql> CREATE user ‘user2’#‘172.19.0.1' IDENTIFIED BY ‘xyz1234’;
mysql> GRANT ALL PRIVILEGES ON *.* TO 'user2'#'172.19.0.1' WITH GRANT
OPTION;
This helped me connect to mysql server running on the docker locally on macos.