Docker compose-simplifies complex container applications

Compose is a tool for defining and running complex Docker applications. You can define a multi-container application in a file, then use a command to launch your app, and all related actions will be automatically completed.

1. Installing Docker and compose

# Currently the latest Docker is 1.6.2,compose for 1.2.0curl-s https://get.docker.io/ubuntu/| sudo shsudo apt-get updatesudo apt-get Install Lxc-docker# Reference http://docs.docker.com/compose/install/#install-composecurl-l https://github.com /docker/compose/releases/download/usr/local/usr/local/bin/docker-compose above this method really slow out of Xiang, Can be installed via Python pip. Apt-get Install Python-pip python-devpip install-u docker-compose        

So compose installed, look at the Compose version information:

/usr/local1.2.  0 

2. Using Compose

Using compose requires a simple three-step process: First, use Dockerfile to define your application environment:

From Python:2.7ADD ./codeworkdir /codeRUN pip install-r requirements.txt  

Among them, the contents of Requirements.txt include:

Flaskredis

And then write a simple app.py in Python.

From Flask importflaskfrom Redis importredisimport osapp =flask (__name__) Redis =redis (host=' Redis ', port=6379) @app. Route ('/')Hello(): REDIS.INCR (' hits ')return' Hello world! I have been seen%s times. ' % Redis.get (' hits ')if __name__ = ="__main__": App.run (host="0.0.0.0", debug=True) 

The second step is to use a compose.yaml to define your application, and they can compose your app in the next isolated container.

WeB:  build:.  python app.py  Ports:-"5000:5000" Volumes:-.:/ Code links:-redisredis:image:redis        

The third step is to execute docker-compose up to launch your app, which will pull/run the two containers according to the Compose.yaml settings.

Creating myapp_redis_1...creating myapp_web_1...building web ... Step0:fromPython:2.72.7:pulling fromPython... Status:downloaded Newer imageForPython:2.7---> D833e0b23482step1:add. /code--->1c04b1b15808removing Intermediate container 9dab91b4410dStep Span class= "Hljs-number" >2:workdir/code---> Running in f495a62feac9---> ffea89a7b090attaching to myapp_redis_1, Myapp_web_1......redis_1 | [1] 17 may  10: 42:38.147 * The server is now ready Span class= "Hljs-keyword" >to Accept connections on port 6379web _1 | * Running on http://0.0. 0.0:5000/(press CTRL + C to quit) web_1 | * Restarting with stat              

3. yaml File Reference

In the Yaml file above, we can see the basic structure of the compose file. The first is to define a service name, and here are some of the option entries in the YAML service:

image: The ID of the mirror

build: Build directly from the dockerfile of PWD, rather than pull by the image option

links: Connect to those containers. Each row, formatted as Service[:alias], for example –db[:d atabase]

external_links: Connect to a container other than the Compose.yaml file, such as a container service that provides shared or generic services. Format with links

command: Replace the default command commands

ports: Export port. The format can be:

"ports:-"-"8000:8000"-"127.0.0.1:8001:8001"  

expose: Export the port, but not to the host's port. It is open only to links ' containers. Format to specify the port number directly.

volumes: Load path as volume, you can specify read-only mode:

volumes:-/var/lib/mysql-cache/:/tmp/cache-~/configs:/etc/configs/:ro   

volumes_from: Load all volumes of other containers or services

environment:-rack_env=development  -Session_secret

env_file: Import environment variable from a file, file format is rack_env=development

extends: Extend another service to override some of these options. A sample is as follows:

Common.ymlwebapp:  build:./webapp  environment:-debug=false-send_emails=  Falsedevelopment.ymlweb:extends: file:common.yml service:webapp ports:-"8000:8000"  links:-db environment:-debug=truedb: image:postgres      

net: The network mode of the container, which can be "bridge", "none", "Container:[name or id", and "host" one.

dns: You can set one or more custom DNS addresses.

dns_search: You can set the scan domain for one or more DNS.

The other working_dir, entrypoint, user, hostname, domainname, mem_limit, privileged, restart, stdin_open, tty, cpu_shares , and the docker run command is the same, these commands are single-line commands. For example:

Cpu_shares:working_dir:/code/code/entrypoint.shuser:postgresqlhostname:fooDomainName : foo.commem_limit:1000000000Privileged:truerestart:alwaysstdin_open:True TTY:true              

4. Docker-compose Common Commands

In the second section, both of docker-compose up these containers are running in the foreground. We can specify the-d command to start the container in a daemon manner. In addition, Docker-compose supports the following parameters:

--verbose: Output Details

-fDevelop a non-docker-compose.yml named Yaml file

-pSet a project name (default is directory name)

Docker-compose's actions include:

build: Build Services

kill -s SIGINT: sends a specific signal to the service.

logs: Output Log

port: Output bound port

ps: Output Running Container

pull: Image of the pull service

rm: Remove a stopped container

run: Run a service, such as Docker-compose run Web python manage.py shell

start: Runs a container that exists in a service.

stop: Stops a container that exists in a service.

up: Create + run + Attach container to service.

scale: Sets the number of containers that the service runs. Example: Docker-compose scale web=2 worker=3

Reference:

Compose Document

Docker compose-simplifies complex container applications