(10) Docker compose installation and creation of flask Web Apps

Docker Compose is one of the Docker orchestration (Orchestration) projects that are responsible for quickly deploying distributed applications in a cluster.

Dockerfile lets users manage a single application container, while Compose allows the user to define a set of associated application containers (called a project, i.e., projects) in a template (YAML format), such as a Web service container plus a backend database service container.

Installation

The project was written by Python and actually invokes the API provided by Docker. by pip Installing.

$ python3 -m pip install docker-compose

After the installation is successful, you can view docker-compose the use of the command.

and run multi-container applications with Docker.Usage:  docker-compose [-f <arg>...] [options] [COMMAND] [ARGS...]  docker-compose -h|--helpOptions:  -f, --file FILE             Specify an alternate compose file (default: docker-compose.yml)  -p, --project-name NAME     Specify an alternate project name (default: directory name)  --verbose                   Show more output  --no-ansi                   Do not print ANSI control characters  -v, --version               Print version and exit -H, --host HOST Daemon socket to connect to ……

Create a Flask app

Create a web app that uses flask and count the values into Redis.

1. Create a Web app

Create a Flask web App, app.py file:

 from flask import Flaskfrom redis import Redisapp = Flask (__name__) Redis = Redis ( Host= ' Redis ', Port=6379)  @app. Route ( '/') def hello  (): REDIS.INCR ( ' hits ') return Span class= "hljs-string" > ' Hello world! I have been seen%s times. '% Redis.get ( ' hits ') if __name__ =  "__main__": App.run (Host= "0.0.0.0", debug= true)             

Create a dependent file requirements.txt with the following content:

flaskredis

2. Create Dockerfile

Under the same directory, create the Dockerfile .

FROM python:3.5ADD . /codeWORKDIR /codeRUN python3 -m pip install -r requirements.txtCMD python3 app.py

Make a brief description of the above dockerfile:

• The container uses a Python 3.5 mirror
• Copy the files in the current directory into the container/code
• Specify the working directory as/code
• Libraries required for installing Python: flask, Redis
• Container execution Command Python3 app.py

3. Create an Orchestration Script

Under the same directory, createdocker-compose.yml

version: ‘1‘services:  web:    build: . ports: - "5000:5000" volumes: - .:/code depends_on: - redis redis: image: redis

Make a brief description of the above orchestration script:

• This app defines two services: Web, Redis
• The Web container is generated from the Dockerfile under the current path
• 5000 ports within the Web container are mapped to 5000 ports on the host
• Mount the current directory inside the Web container/code
• The Web container relies on the Redis container
• Redis container gets mirroring from Docker hub

All files are ready.

$ lsapp.py  docker-compose.yml  Dockerfile  requirements.txt

4. Start the application

docker-composeExecute the Orchestration script, create and crawl the Web,redis image, and start the container separately.

$ sudo docker-compose up……redis_1  | 1:M 02 Feb 04:13:15.129 * Ready to accept connectionsweb_1    |  * Running on http://0.0.0.0:5000/ (Press CTRL+C to quit)web_1    |  * Restarting with statweb_1    |  * Debugger is active!web_1    | * Debugger PIN: 170-376-971

The whole process will be long ...

5. Access to Applications

Open Browser Orientation: http://0.0.0.0:5000/

The effect is as follows:

(10) Docker compose installation and creation of flask Web Apps