Docker (B): a vessel container

docker hierarchy can be divided into three layers, from the bottom up is: a container (container), service (services), the stack (stack), which defines the behavior of container services, stack defines the interactive services of
the next attempt is how to use docker start an application in a container

Create a container

1. Create an empty folder that contains Dockerfile, app.py, requirements.txt three files, file contents are as follows

Dockerfile

# 使用python的运行环境作为parent image
FROM python:2.7-slim

# 设置工作路径
WORKDIR /app

# 将当前目录的内容复制到相应路径下
COPY . /app

# 下载requirements.txt中要求的包
RUN pip install --trusted-host pypi.python.org -r requirements.txt

# 暴露容器的80端口
EXPOSE 80

# 定义环境变量
ENV NAME World

#当docker开始运行时执行文件
CMD ["python", "app.py"]

requirements.txt

Flask
Redis

app.py

from flask import Flask
from redis import Redis, RedisError
import os
import socket

# Connect to Redis
redis = Redis(host="redis", db=0, socket_connect_timeout=2, socket_timeout=2)

app = Flask(__name__)

@app.route("/")
def hello():
    try:
        visits = redis.incr("counter")
    except RedisError:
        visits = "<i>cannot connect to Redis, counter disabled</i>"

    html = "<h3>Hello {name}!</h3>" \
           "<b>Hostname:</b> {hostname}<br/>" \
           "<b>Visits:</b> {visits}"
    return html.format(name=os.getenv("NAME", "world"), hostname=socket.gethostname(), visits=visits)

if __name__ == "__main__":

Building applications

Use the following command to build applications

docker build --tag=friendlyhello  .
# or  docker build -t=friendlyhello  .

Use docker image lscan view the image building

 $  docker image ls
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
friendlyhello       latest              7ecc82fd960a        53 minutes ago      148MB
python              2.7-slim            5f759d36aead        7 hours ago         137MB
hello-world         latest              fce289e99eb9        7 months ago        1.84kB

TAG which is the default latest, you can use --tag=friendlyhello:v0.0.1.to specify the tag

Run the application

Use the following statements to run the program

docker run -p 4000:80 friendlyhello

Which -p 4000:80shows a map image 80 of the port to the host port 4000.
Run http://localhost:4000can view the result of the program
use -dcan let the program running in the background

$ docker run -d -p 4000:80 friendlyhello
c21b81020e77e9f15df5fafbfdaf2791599c6233b4169615ea9226f243ff68b8

$ docker container ls
CONTAINER ID        IMAGE               COMMAND             CREATED              STATUS              PORTS                  NAMES
c21b81020e77        friendlyhello       "python app.py"     About a minute ago   Up About a minute   0.0.0.0:4000->80/tcp   elegant_raman

# 关闭程序
$ docker container stop c21b

$ docker container ls
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

Related Commands

docker build -t friendlyhello .  # Create image using this directory's Dockerfile
docker run -p 4000:80 friendlyhello  # Run "friendlyhello" mapping port 4000 to 80
docker run -d -p 4000:80 friendlyhello         # Same thing, but in detached mode
docker container ls                                # List all running containers
docker container ls -a             # List all containers, even those not running
docker container stop <hash>           # Gracefully stop the specified container
docker container kill <hash>         # Force shutdown of the specified container
docker container rm <hash>        # Remove specified container from this machine
docker container rm $(docker container ls -a -q)         # Remove all containers
docker image ls -a                             # List all images on this machine
docker image rm <image id>            # Remove specified image from this machine
docker image rm $(docker image ls -a -q)   # Remove all images from this machine
docker login             # Log in this CLI session using your Docker credentials
docker tag <image> username/repository:tag  # Tag <image> for upload to registry
docker push username/repository:tag            # Upload tagged image to registry
docker run username/repository:tag                   # Run image from a registry