Docker Compose Project

http://hongge.blog.51cto.com/

Docker Compose Project

Compose Project Introduction

The compose project originates from the previous Fig project and is written in Python code. The Compose project is primarily used to orchestrate the deployment of Docker-based applications. It has a high degree of coordination with Docker/swarm.

Docker Compose is part of the Docker Orchestration service that allows users to quickly install Docker,swarm on other platforms, allowing Docker containers to function efficiently in a cluster, while Compose allows users to deploy distributed applications in a cluster. Simply put, Docker Compose belongs to an "application layer" service that allows users to define which container group to run which application, which supports dynamic change of the application and expands as needed.
Compared to kubernetes, the function is relatively simple, which is equivalent to a subset of Kubernetes.

Dockerfile Allows users to manage a single application container , and Compose lets the user in a template (yaml format ) defines a set of associated application containers in ( referred to as a project , that is, an item ), For example, a scheduler, two Web the service container plus the backend database service container, and so on.

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Before installing compose, you should install Docker first, and you won't say it here.

Installing Docker-compose

Install PIP First

Note: Pip is similar to Yum in Redhat, it is very convenient to install Python package

#wget https://bootstrap.pypa.io/get-pip.py

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#python get-pip.py

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Re-install Compose

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After the installation is successful, you can view the version of Docker-compose and the usage of the command.

#docker-compose–v

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#docker-compose–h

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First, several terms are introduced.

Service: An application container that can actually run multiple instances of the same mirror.

Project: A complete business unit that consists of a set of associated application containers.

As can be seen, a project may be associated with multiple services (containers), Compose for project management.

Docker-compose Command Description

Most compose commands are run on one or more services, and if the service is not specified, the command will be applied to all services, and if you want to obtain all available information, use the command: docker-compose [COMMAND] --help

Build
Create or re-build services
When the service is created, it is marked as project_service (for example, composetest_db), and if a service is changed dockerfile or the content of the build directory can be used docker-compose build to reconstruct it

Help
Show help and usage information for commands

Kill
A SIGKILL container that is forced to stop operation by sending a signal that can be selectively passed, such as:
docker-compose kill -s SIGKINT

Logs
Display the log output of the service

Port
Output public information for port bindings

Ps
Display container

Pull
Pull Service Image

Rm
To delete a stopped container

Run
Run a one-time command on the service, such as:
docker-compose run webPythonmanage.py shell

Scale
The number of containers that are set to start for a service is specified in the form of such parameters: Service=num, for example:
docker-compose scale web=2 worker=3

Start
Start a container that already exists as a service

Stop
Stop running containers without deleting them, they can be restarted with commands docker-compose start

Up
Build, create, launch, attach to a container for a service
The connected services will be started unless they are already running

Run docker-compose up -d will start the container in the background and make them run

–verbose
Show more output

–version
Show version number and exit

-f,–file file
Specify an optional compose Yaml file (default: DOCKER-COMPOSE.YML)

-p,–project-name Name
Specify an optional project name (default: current directory name)

DOCKER-COMPOSE.YML Command Description

Each service defined in DOCKER-COMPOSE.YML must explicitly specify an image or Build option, which corresponds to the same as entered in the Docker Run command line, for Docker run, The options specified in the Dockerfile file (such as CMD, EXPOSE, VOLUME, ENV) are default, so you do not have to specify it again in Docker-compose.yml

Image

Indicates the ID of the image, the image ID can be local or remote, and if the local does not exist, compose will try to pull down

Image:ubuntu

Image:orchardup/postgresql

Image:a4bc65fd

Build

This parameter specifies the path to the Dockerfile file, which is also the build environment that is sent to the daemon (which is a bit), compose will be built and tagged with an existing name and then use this image

Build:/path/to/build/dir

Command

Overrides the default command, overwriting the command that is executed by default after the container starts

Command: Commands to execute

Links

To connect to a container in another service, you can specify the service name and the alias of the link, or specify only the service name

Links

-DB

-Db:database

-Redis

At this point, inside the container, an entry is created with an alias in the/etc/hosts file, just like this:

172.17.2.186 DB

172.17.2.186 Database

172.17.2.186 Redis

Environment variables will also be created, and arguments about the environment variables will be described later

External_links

Connect to a container that is launched outside of this docker-compose.yml file or compose, especially for containers that provide shared and public services. When specifying a container name and alias, External_links follows the same semantic usage as links

External_links:

-Redis_1

-Project_db_1:mysql

-Project_db_1:postgresql

Ports

exposing ports, specifying both ports (Host: Container), or just the port of the container (the host is randomly assigned a port)

Note: When a port is mapped in the form of a host: container, if the port of the container is less than 60, an error may occur because YAML resolves the data in such a format as XX:YY to 60 binary data, for this reason, always remember to explicitly specify the port mapping as a string

Ports

-"3000"

-"8,000:8,000"

-"49,100:22"

-"127.0.0.1:8001:8001"

Expose

Exposing ports without having to publish them to the host, but only to the linked services (linked service), only the internal ports can be specified

Expose

-"3000"

-"8000"

Volumes

The mount path is the most volume, optionally specifying a path (host: Container) on a host, or a mode (host: container: RO) that can be used

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

Volumes_from:

Mount all of its volumes from another service or container.

Volumes_from:

-Service_Name

-Container_name

Environment

Add environment variables, you can use an array or a dictionary, only one key environment variable can find the corresponding value on the machine running compose, which helps the value of the encrypted or special host

Environment:

Rack_env:development

Session_secret:

Environments:

-Rack_env=development

-Session_secret

Env_file

Add an environment variable from a file

If a template file is specified by docker-compose-f files, the path in Env_file is based on the template file path. If there is a conflict between the variable name and the environment directive, the latter will prevail.

Env_file:. env
Env_file:
-./common.env
-./apps/web.env
-/opt/secrets.env
Each row in the environment variable file must conform to the format, and the comment lines that begin with # are supported.
# Common.env:Set Rails/rack Environment
Rack_env=development

Net

Network mode, you can specify these values in the--net parameter of the Docker client

NET: "Bridge"

NET: "None"

NET: "Container:[name or ID"

NET: "Host"

Dns

Custom DNS service, which can be a single value or a list

dns:8.8.8.8

Dns:

-8.8.8.8

-9.9.9.9

Dns_search

Custom DNS search scopes can be individual values or a list

Dns_search:example.com

Dns_search:

-Dc1.example.com

-Dc2.example.com

A simple three-step process is required to use compose:

First, use Dockerfile or Docker commit to define your application environment

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

The third step is to execute Docker-compose up-d to launch your app, which will pull/run related containers based on docker-compose.yml settings.

Test case

Below, we create a classic Web project: A Haproxy that mounts three web containers.

The Docker-haproxy directory, which is the project working directory, in which you create two subdirectories: Haproxy and web.

#mkdir-P/root/docker-haproxy/{haproxy,web}

Create a docker-compose.yml file under the/root/docker-haproxy/directory

Create the Haproxy Master profile in the/root/docker-haproxy/haproxy directory haproxy.cfg

Storing web site page files in the/root/docker-haproxy/web directory

The directory structure looks like this:

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Web Sub-directory:

Generate a index.html file with the contents:

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Haproxy directory:

In which a haproxy.cfg file is generated

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Docker-compose.yml

Write the Docker-compose.yml file, which is the main template file used by compose. The content is simple, specifying 3 web containers, and 1 haproxy containers.

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To run the Compose project:

Execute Docker-compose up-d in the Docker-haproxy directory to launch your app

#cd Docker-haproxy

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To view container startup conditions

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Or

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Open Browser native native ip:http://192.168.1.105

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Open Browser native native ip:http://192.168.1.105:70

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http://hongge.blog.51cto.com/

Docker Compose Project