英文:
I do not understand why I can not connect to mysql using docker compose golang mariadb/mysql multi container app
问题
尝试创建一个使用Golang和MySQL的多容器应用程序，类似于Docker示例https://docs.docker.com/get-started/07_multi_container/。
我不明白为什么连接被拒绝。
dial tcp 127.0.0.1:3306: connect: connection refused
这是我的docker-compose.yaml文件：
version: '3.7'
services:
api:
# api服务正常启动，但在连接数据库时出现致命错误
maria-db:
image: mariadb:10-focal
container_name: s-maria-db
command: '--default-authentication-plugin=mysql_native_password'
restart: always
healthcheck:
test: ["CMD-SHEL", "mysqladmin ping -h 127.0.0.1 --password=secret --silent"]
interval: 3s
retries: 5
start_period: 30s
expose:
- "3306:3306"
# 设置一些环境变量来创建数据库
environment:
MYSQL_ROOT_PASSWORD: "secret"
MYSQL_DATABASE: "s_db"
# 挂载数据卷以确保不丢失数据
volumes:
- db-data:/var/lib/mysql
volumes:
db-data:
这是我连接数据库的Go代码：
func Connect() (*sql.DB, error) {
db, err := sql.Open("mysql", "root:secret@/s_db")
if err != nil {
return nil, err
}
defer db.Close()
pingErr := db.Ping()
if pingErr != nil {
return nil, pingErr
}
return db, nil
}
我总是看到dial tcp 127.0.0.1:3306: connect: connection refused的错误。
我可以执行以下命令：
docker exec -it s-maria-db bash
.
.
.
MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| s_db |
| mysql |
| performance_schema |
| sys |
+--------------------+
并且可以看到数据库已正确配置，但我无法连接到它。
英文:
Attempting to create a golang mysql multi container app. Similar to docker example https://docs.docker.com/get-started/07_multi_container/
I do not understand why connection is refused.
dial tcp 127.0.0.1:3306: connect: connection refused
Here is my docker-compose.yaml
version: '3.7'
services:
api:
# api service starts ok but fatal error at db connection
maria-db:
image: mariadb:10-focal
container_name: s-maria-db
command: '--default-authentication-plugin=mysql_native_password'
restart: always
healthcheck:
test: ["CMD-SHEL", "mysqladmin ping -h 127.0.0.1 --password=secret --silent"]
interval: 3s
retries: 5
start_period: 30s
expose:
- "3306:3306"
# setting some env vars to create the DB
environment:
MYSQL_ROOT_PASSWORD: "secret"
MYSQL_DATABASE: "s_db"
# we mount a data volume to make sure we don't lose data
volumes:
- db-data:/var/lib/mysql
volumes:
db-data:
Here is my go-code to connect to db
func Connect() (*sql.DB, error) {
db, err := sql.Open("mysql", "root:secret@/s_db")
if err != nil {
return nil, err
}
defer db.Close()
pingErr := db.Ping()
if pingErr != nil {
return nil, pingErr
}
return db, nil
}
I always see dial tcp 127.0.0.1:3306: connect: connection refused
I can
docker exec -it s-maria-db bash
.
.
.
MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| s_db |
| mysql |
| performance_schema |
| sys |
+--------------------+
and see the db is configured correctly , but I can never connect to it.
答案1
得分: 2
尝试使用容器的名称进行连接，因为Docker Compose使用Docker网络。这样可以通过容器的名称作为网络别名进行连接。
func Connect() (*sql.DB, error) {
db, err := sql.Open("mysql", "root:secret@tcp(s-maria-db)/s_db")
if err != nil {
return nil, err
}
defer db.Close()
pingErr := db.Ping()
if pingErr != nil {
return nil, pingErr
}
return db, nil
}
英文:
try to connect using container's name hence docker composer uses docker network. That allows you to connect via container's name as a network alias.
func Connect() (*sql.DB, error) {
db, err := sql.Open("mysql", "root:secret@tcp(s-maria-db)/s_db")
if err != nil {
return nil, err
}
defer db.Close()
pingErr := db.Ping()
if pingErr != nil {
return nil, pingErr
}
return db, nil
}
答案2
得分: 2
此外，更新的代码如下：
for i := 0; i < 60; i++ {
if err := db.Ping(); err == nil {
fmt.Print("我们已连接！")
break
}
time.Sleep(time.Second)
}
代码来源：https://github.com/docker/awesome-compose/blob/master/nginx-golang-mysql/backend/main.go
英文:
Additionally updated go with
for i := 0; i < 60; i++ {
if err := db.Ping(); err == nil {
fmt.Print("We are connected!")
break
}
time.Sleep(time.Second)
}
as seen https://github.com/docker/awesome-compose/blob/master/nginx-golang-mysql/backend/main.go
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