两个容器之间的数据库连接被拒绝

Question

我有一个mysql数据库，运行了以下docker-compose.yml：

version: '3.3'
    services:
        db:
            image: mysql:5.7
            restart: always
            environment:
                MYSQL_DATABASE: 'demo'
                # So you don't have to use root, but you can if you like
                MYSQL_USER: 'user'
                # You can use whatever password you like
                MYSQL_PASSWORD: 'password'
                # Password for root access
                MYSQL_ROOT_PASSWORD: 'password'
            ports:
            #  : < MySQL Port running inside container>
                - '3306:3306'
            expose:
                # Opens port 3306 on the container
                - '3306'
            # Where our data will be persisted
            volumes:
                - my-db:/var/lib/mysql
            networks:
                - backend

networks:
    backend:
        driver: bridge
# Names our volume
volumes:
    my-db:

$ docker-compose build

$ docker-compose up

我使用以下Dockerfile提供了一个基本的golang：

# Start from golang:1.12-alpine base image
FROM golang:1.12-alpine

# Adding git, bash and openssh to the image
RUN apk update && apk upgrade && \
    apk add --no-cache bash git openssh


# Set the Current Working Directory inside the container
WORKDIR /app


# Copy the source from the current directory to the Working Directory inside the container
COPY . .
RUN go get -d github.com/gorilla/mux
RUN go get -d github.com/go-sql-driver/mysql
RUN go get -d github.com/golang-migrate/migrate
RUN go get -d github.com/golang-migrate/migrate/database/mysql
RUN go get -d github.com/golang-migrate/migrate/source/file



# Build the Go app
RUN go build -o main .

# Expose port 8080 to the outside world
EXPOSE 8080

# Run the executable
CMD ["./main"]

以下函数称为：

func CreateDatabase() (*sql.DB, error) {
    serverName := "localhost:3306"
    user := "user"
    password := "password"
    dbName := "demo"

    connectionString := fmt.Sprintf("%s:%s@tcp(%s)/%s?charset=utf8mb4&collation=utf8mb4_unicode_ci&parseTime=true&multiStatements=true", user, password, serverName, dbName)
    db, err := sql.Open("mysql", connectionString)
    if err != nil {
        return nil, err
    }

    if err := migrateDatabase(db); err != nil {
        return db, err
    }

    return db, nil
}

$ docker run -p 80:8080 --network=-mysql_backend

$ Database connection failed: %sdial tcp 127.0.0.1:3306: connect: connection refused

我无法获得api来与数据库容器建立数据库连接？

Answer 1

您的golang应该包含在撰写文件中，并添加到同一个网络中。

当您运行golang时，您还会将它添加到backend以外的网络中，后者是在您的撰写文件中创建的网络。

Answer 2

除了将app容器连接到同一个backend网络之外，还需要在连接字符串中修复MySQL主机参数。

查看main函数，将MySQL主机设置为localhost

serverName := "localhost:3306"

但是，MySQL没有监听appc容器的lcoalhost，您需要在复合文件(即db )中将其更改为MySQL服务名称。