This topic describes how to deploy and use Docker on an ECS instance that runs an Alibaba Cloud Linux 2.1903 LTS 64-bit operating system. This tutorial is intended for developers who are familiar with Linux but new to Alibaba Cloud ECS.

Prerequisites

  • An Alibaba Cloud account is created. To create an Alibaba Cloud account, go to the account registration page.
  • At least one instance is created. For more information, see Create an instance by using the wizard.
    The following instance configurations are used in the examples:
    • Instance type: ecs.g6.large
    • Operating system: Alibaba Cloud Linux 2.1903 LTS 64-bit
      Note The operation commands described in this example can also be used in the CentOS 7 operating system.
    • Network type: VPC
    • IP address: a public IP address

Background information

This topic describes the following operations:
  • Deploy Docker. For more information, see the Deploy Docker section.
  • Use Docker.
    • For information about the basic usage of Docker, see the Use Docker section.
    • For information about how to create a Docker image, see the Create a Docker image section.

Deploy Docker

This section describes how to manually install Docker. You can also purchase the required image from Alibaba Cloud Marketplace and easily deploy Docker.

  1. Remotely connect to an ECS instance. For more information, see Overview.
  2. Perform the following operations in sequence to add the YUM repository:
    • Update the YUM repository.
      yum -y update
    • Install the EPEL repository.
      yum install -y epel-release
    • Remove the YUM cache.
      yum clean all
    Note You can run the yum list command to view all available packages.
  3. Install and run Docker.
    yum install docker-io -y
systemctl start docker
  4. Check the installation result.
    docker info
    If the following information is displayed, Docker is installed.site

Use Docker

You can use Docker in the following ways:
  • Manage the Docker daemon. 
    systemctl start docker     #Run the Docker daemon.
systemctl stop docker      #Stop the Docker daemon.
systemctl restart docker   #Restart the Docker daemon.
systemctl enable docker    #Configure Docker to run on system startup.
  • Manage images. Apache images from Alibaba Cloud Container Registry are used in the following examples. 
    docker pull registry.cn-hangzhou.aliyuncs.com/lxepoo/apache-php5
    • Modify the tags of images from Alibaba Cloud Container Registry to simplify image identification. 
      docker tag registry.cn-hangzhou.aliyuncs.com/lxepoo/apache-php5:latest aliweb:v1
    • Check existing images. 
      docker images
    • Force delete an image. 
      docker rmi -f registry.cn-hangzhou.aliyuncs.com/lxepoo/apache-php5
  • Manage containers.
    • Enter a container. Run the docker images command to obtain the ImageId value, which is e1abc****. Then, run the docker run command to access the container. 
      docker run -it e1abc**** /bin/bash
    • Exit the container. Run the exit command to exit the container.
    • You can combine the run command with the –d parameter to run the container in the background. The --name parameter specifies apache as the container name. 
      docker run -d --name apache e1abc****
    • Access the container that runs in the background. 
      docker exec -it apache /bin/bash
    • Query the container ID.
      docker ps
    • Create an image from the container. Description of the parameters in the command: docker commit <Container ID or container name> [<Repository name> [: <Tag>]]. 
      docker commit containerID/containerName repository:tag
    • To easily test and restore an image, you can run the source image, derive a new image that has a simple name from the source image, and then test the new image. 
      docker commit 4c8066cd8**** apachephp:v1
    • Run the container and map port 8080 of the host to the container. 
      docker run -d -p 8080:80 apachephp:v1
      In a browser, enter the IP address of the instance followed by the port number 8080 to connect to the container. The following response indicates that the container runs normally.
      Note An inbound rule must be added to a security group of the ECS instance to allow inbound traffic on port 8080. For more information, see Add security group rules.
      Mapping result

Create a Docker image

  1. Prepare Dockerfile.
    1. Create and edit Dockerfile.
      vim Dockerfile
    2. Press the I key to enter the edit mode. Add the following content to the file:
      #Declare a base image.
FROM apachephp:v1
#Declare the owner of the base image.
MAINTAINER DTSTACK
#The commands that you want to run before the container starts. You must append these commands to the end of the RUN command. Dockerfile can contain only a maximum of 127 lines. If you have commands that exceed 127 lines, we recommend that you write these commands to a script.
RUN mkdir /dtstact
#The commands that run on system startup. The last command must be a frontend command that runs constantly. Otherwise, the container exits after all commands are run.
ENTRYPOINT ping www.aliyun.com
    3. Press the Esc key. Enter :wq and press the Enter key to save and exit Dockerfile.
  2. Build an image.
    docker build -t webalibabacloudlinux:v1 .    # . specifies the path of Dockerfile and must be provided.
docker images                                #Check whether the image is built.
  3. Run the container and check its status.
    docker run -d webalibabacloudlinux:v1    #Run the container in the background.
docker ps                                #Query the containers that are in the running state.
docker ps -a                             #Query all containers, including those in the stopped state.
docker logs CONTAINER ID/IMAGE           #Check the startup log to troubleshoot the issue based on the container ID or name if the container does not appear in the query results.
  4. Create an image.
    docker commit fb2844b6**** dtstackweb:v1     #Append the container ID and the name and version number of the new image to the end of the commit parameter.
docker images                                #Query images that are downloaded and created on premises.
  5. Push the image to a remote repository.
    By default, the image is pushed to Docker Hub. You must log on to Docker, bind a tag to the image, and then name the image in the <Docker username/image name:tag> format. Then the push is complete. 
    docker login --username=dtstack_plus registry.cn-shanghai.aliyuncs.com #Specify the password of the image repository. Enter the password after you run this command.
docker tag [ImageId] registry.cn-shanghai.aliyuncs.com/dtstack123/test:[Tag]
docker push registry.cn-shanghai.aliyuncs.com/dtstack123/test:[Tag]