How to start the service in the container in docker

With the increasing popularity of containerization technology, Docker has become the representative of containerization technology. Docker's simplicity and ease of use have made it a mainstream tool for containerization technology. But for beginners, how to start the service in the container may be a difficult point. In this article, we will introduce how Docker starts services in containers.

Install docker

First, we need to install Docker locally. For specific methods of installing Docker, please refer to official documentation or other related information. After the installation is complete, we can use the docker command to determine whether Docker is installed correctly. You can check the version of Docker by executing the following command:

docker version

Open container

Once Docker is installed, we need to start a container in Docker. A container in Docker refers to all the components and libraries needed to run a complete application. We can download the image from Docker Hub to start the container, or we can make an image ourselves. Regarding the production of mirrors, I will not go into details here. It is assumed here that we already have an image named myimage.

The command syntax to start the container is:

docker run [OPTIONS] IMAGE[:TAG|@DIGEST] [COMMAND] [ARG...]

• OPTIONS: Optional parameter list.
• IMAGE[:TAG|@DIGEST]: The image or version number to be started.
• COMMAND: The command that the container needs to run.
• ARG...: Parameters of the command.

The more commonly used options are:

• -p port:port: Specify the rules for port mapping between the container and the host.
• -d: Indicates running in background mode.
• -v host:container: Use the mount command to realize data sharing between the host directory and the container directory.
• --name name: Specify the container name.

Start the container through the following command:

docker run --name mycontainer -d -p 8080:80 myimage

With the above command, we use the myimage image as a template to start a background container named mycontainer, and at the same time set the 80 port inside the container Map to local port 8080.

View container status

After starting the container, we need to confirm the container status. You can check the container status through the following command:

docker ps

After executing the above command, we can get something similar to the following:

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                  NAMES
b318194bdaf2        myimage             "nginx -g 'daemon of…"   About an hour ago   Up About an hour    0.0.0.0:8080->80/tcp   mycontainer

From this output, you can see the container ID and the image used. , information such as the command run by the container and the mapped port. If you don't see the container you just started, you can use the docker ps -a command to view the status of all containers.

Enter the container

If we need to operate inside the container, we can enter the container through the following command:

docker exec -it <容器ID或名称> <命令>

For example, the following command can enter the bash terminal in the mycontainer container :

docker exec -it mycontainer bash

The -it option of this command indicates that we need to open an interactive tty terminal and let the bash shell inside the container execute the command.

Service operation in the container

Through the above steps, we have successfully started the Docker container and can enter the container. Next, we need to start the service in the container.

For common services, such as web services (nginx, Apache), database services (MySQL, PostgreSQL, etc.), we can start these services through the following commands:

# 启动nginx服务
docker exec -it mycontainer service nginx start

# 启动MySQL服务
docker exec -it mycontainer service mysql start

You can also use the following commands Command to manually start the service:

docker exec -it mycontainer <service_name> <command>

Here just replace <service_name> with the name of the service you need to start, and <command> with the required execution command.

Summary

The above is how to open the internal service of the container in Docker. First, you need to install the Docker tool and start the container in the Docker environment. After entering the container, you can start the services inside the container by executing commands. Docker brings greater flexibility and scalability to containerization technology. I believe that mastering the above skills will help you take a further step in containerization technology.

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