Docker安装

yum remove docker docker-client docker-client-latest docker-common docker-latest docker-latest-logrotate docker-logrotate docker-engine

sudo yum install -y docker-ce docker-ce-cli containerd.io

systemctl enable docker --now

mkdir -p /etc/docker/
tee /etc/docker/daemon.json <<-'EOF'
{
  "registry-mirrors": ["https://82m9ar63.mirror.aliyuncs.com"],
  "exec-opts": ["native.cgroupdriver=systemd"],
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "100m"
  },
  "storage-driver": "overlay2"
}
EOF
systemctl daemon-reload
systemctl restart docker

Docker-compose安装

curl -L "https://github.com/docker/compose/releases/download/1.29.2/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
chmod +x /usr/local/bin/docker-compose
docker-compose --version

第一题

FROM naqoda/mysql-client # 一个只有centos7和mysql客户端的镜像
WORKDIR /root
RUN mkdir /data/ && touch /data/log
RUN touch /root/count.sh
RUN echo '#!/bin/bash'  >> /root/count.sh
RUN echo 'host=$1'  >> /root/count.sh
RUN echo 'port=$2'  >> /root/count.sh
RUN echo 'user=$3'  >> /root/count.sh
RUN echo 'while :'  >> /root/count.sh
RUN echo 'do'  >> /root/count.sh
RUN echo 'msg=`mysql -h $1 -P $port -u$user -e "show status like '\''Threads_connected'\'';"|awk '\''NR==2{print$2}'\''`'  >> /root/count.sh
RUN echo 'echo [`date "+%Y-%m-%d %H:%M:%S"`] Number of active DB connections is $msg. |tee -a /data/log'  >> /root/count.sh
RUN echo 'sleep 30'  >> /root/count.sh
RUN echo 'done'  >> /root/count.sh
CMD bash /root/count.sh $HOST $PORT $USER

# 在Dockerfile所在目录构建
docker build -t counter:v0.1 .
docker images    # 获取 counter的IMAGE_ID
docker run -e HOST=47.94.218.68 \
           -e PORT=3306 \
           -e USER=root \
           -e MYSQL_PWD=123456 \
           -d IMAGE_ID
docker ps         # 获取counter的CONTAINER_ID
docker logs CONTAINER_ID                                                    # 方法一
docker exec -it CONTAINER_ID tail -f /data/log        # 方法二

第二题

version: "3.9"
services:
  mysql-server:
    image: mysql:5.7
    container_name: mysql-server
    restart: always
    ports: 
      - 3306:3306
    environment:
      MYSQL_ROOT_PASSWORD: 123456
  counter:
    build: .
    depends_on:
      - mysql-server
    restart: always
    environment:
      HOST: mysql-server
      PORT: 3306
      USER: root
      MYSQL_PWD: 123456

docker-compose up        # 启动，可以加 -d 后台启动
# 新建一个会话
docker ps         # 获取counter的CONTAINER_ID
docker logs CONTAINER_ID                                                    # 方法一
docker exec -it CONTAINER_ID tail -f /data/log        # 方法二