Introduction to the use of Docker-Compose

Docker quick start-Docker-Compose

1. Introduction to Docker-Compose

1. Introduction to Docker-Compose

The Docker-Compose project is an official open source project of Docker, responsible for the rapid orchestration of Docker container clusters.
Docker-Compose divides the managed containers into three layers, namely project, service and container. All the files (docker-compose.yml, extends files or environment variable files, etc.) in the Docker-Compose running directory form a project. If there is no special designation, the project name is the current directory name. A project can contain multiple services, and each service defines the image, parameters, and dependencies for the container to run. A service can include multiple container instances. Docker-Compose does not solve the problem of load balancing, so other tools need to be used to realize service discovery and load balancing.
The project configuration file of Docker-Compose is docker-compose.yml by default. The configuration file can be customized through the environment variable COMPOSE_FILE or -f parameter, which defines multiple dependent services and the container in which each service runs.
Using a Dockerfile template file allows users to easily define a separate application container. In work, we often encounter situations that require multiple containers to cooperate with each other to complete a task. For example, to implement a Web project, in addition to the Web service container itself, it is often necessary to add a back-end database service container, or even a load balancing container.
Compose allows users to define a group of associated application containers as a project through a single docker-compose.yml template file (YAML format).
The Docker-Compose project is written in Python and calls the API provided by the Docker service to manage containers. Therefore, as long as the operating platform supports the Docker API, you can use Compose on it for orchestration management.

2. Docker-Compose installation

Installation method 1:
Download Docker-Compose:

sudo curl -L https://github.com/docker/compose/releases/download/1.23.0-rc3/docker-compose-`uname -s`-`uname -m` -o /usr/local/bin/docker-compose

Install Docker-Compose:

sudo chmod +x /usr/local/bin/docker-compose

View version:

docker-compose version

Installation method two:
install pip

yum -y install epel-release
yum -y install python-pip

Confirm version

pip --version

Update pip

pip install --upgrade pip

Install docker-compose

pip install docker-compose

View version

docker-compose version

Install completion tool:
In order to facilitate the input of commands, you can also install Docker's completion prompt tool to help you quickly enter commands:
install

yum install bash-completion

Download the docker-compose script

curl -L https://raw.githubusercontent.com/docker/compose/$(docker-compose version --short)/contrib/completion/bash/docker-compose > /etc/bash_completion.d/docker-compose

3. Docker-Compose uninstallation
If it is installed as a binary package, just delete the binary file:

sudo rm /usr/local/bin/docker-compose

If installed through the Python pip tool, execute the following command to delete:

sudo pip uninstall docker-compose

Two, Docker-Compose commonly used commands

1. Docker-Compose command format

docker-compose [-f …] [options] [COMMAND] [ARGS…]

The command options are as follows:
-f, -file FILE specifies the Compose template file, the default is docker-compose.yml, which can be specified multiple times.
-p, -project-name NAME specifies the name of the project. By default, the name of the directory will be used as the project name.
-x-network-driver uses Docker's pluggable network backend feature (requires Docker 1.9+ version)
-x-network-driver DRIVER specifies the driver of the network backend, the default is bridge (requires Docker 1.9+ version)
-verbose output more Multiple debugging information
-v, -version print version and exit

2、docker-compose up

docker-compose up [options] [–scale SERVICE=NUM…] [SERVICE…]

Options include:
-d Run the service container in the background
–no-color Do not use color to distinguish the control output of different services
–no-deps Do not start the container linked to the service
–force-recreate Force the container to be recreated, cannot be combined with –no- Use recreate at the same time
–no-recreate If the container already exists, it will not be recreated. It cannot be used at the same time with –force-recreate
–no-build Does not automatically build the missing
service image
–build Build the service image before starting the container –abort-on- container-exit stops all containers. If any container is stopped, it cannot be used with -d at the same time.
-t, --timeout TIMEOUT Timeout when stopping the container (default is 10 seconds)
--remove-orphans delete service is not defined in compose file Container
–scale SERVICE=NUM Set the number of service running containers, which will override the parameters specified by scale in compose

docker-compose up

Start all services

docker-compose up -d

In the background, all startup services
-f specify the use of the Compose template file, the default is docker-compose.yml, you can specify multiple times.

docker-compose -f docker-compose.yml up -d

3 、 docker-compose ps

docker-compose ps [options] [SERVICE…]

docker-compose ps

List all current containers in the project

4、docker-compose stop

docker-compose stop [options] [SERVICE…]

Options include:
-t, --timeout TIMEOUT Timeout when stopping the container (default is 10 seconds)

docker-compose stop

Stop the running container, you can start it again through docker-compose start

5、docker-compose -h

docker-compose -h

View help

6、docker-compose down

docker-compose down [options]

Stop and delete containers, networks, volumes, and mirrors.
Options include:
-rmi type, delete the mirror, the type must be: all, delete all mirrors defined in the compose file; local, delete the mirror with an empty mirror name
-v, -volumes, delete the anonymous and anonymous ones that have been defined in the compose file The data volume attached to the container
–remove-orphans, delete the container in the service that is not defined in compose

docker-compose down

Disable the removal of all containers and network related

7、docker-compose logs

docker-compose logs [options] [SERVICE…]

View the output of the service container. By default, docker-compose will use different colors to distinguish different service outputs. The color can be turned off by -no-color.

docker-compose logs

View the output of the service container

8、docker-compose build

docker-compose build [options] [–build-arg key=val…] [SERVICE…]

Build (rebuild) the service container in the project.
Options include:
–compress build the upper and lower environment through gzip compression
–force-rm delete the temporary container during the build process
–no-cache do not use the cache during the image building process
–pull always try to get the updated version of the image through the pull operation
-m, –Memory MEM sets the memory size for the built container
–build-arg key=val sets the build-time variable for the
service Once the service container is built, it will carry a tag name. You can run docker-compose build in the project directory at any time to rebuild the service

9、docker-compose pull

docker-compose pull [options] [SERVICE…]

Pull the image that the service depends on.
Options include:
-ignore-pull-failures, ignore errors in the process of pulling mirrors
-parallel, pull multiple mirrors at the same time
-quiet, do not print progress information during the mirroring process

docker-compose pull

Pull the image that the service depends on

10、docker-compose restart

docker-compose restart [options] [SERVICE…]

Restart the services in the project.
Options include:
-t, -timeout TIMEOUT, specify the timeout for stopping the container before restarting (10 seconds by default)

docker-compose restart

Restart the services in the project

11、docker-compose rm

docker-compose rm [options] [SERVICE…]

Delete all (stopped) service containers.
Options include:
-f, -force, force direct deletion, including non-stop container
-v, delete the data volume mounted by the container

docker-compose rm

Delete all (stopped) service containers. It is recommended to execute the docker-compose stop command first to stop the container.

12、docker-compose start

docker-compose start [SERVICE…]

docker-compose start

Start the existing service container.

13、docker-compose run

docker-compose run [options] [-v VOLUME…] [-p PORT…] [-e KEY=VAL…] SERVICE [COMMAND] [ARGS…]

Execute a command on the specified service.

docker-compose run ubuntu ping www.baidu.com

Execute a ping command on the specified container.

14、docker-compose scale

docker-compose scale web=3 db=2

Set the number of containers running the specified service. Set the number through the parameter of service=num

15、docker-compose pause

docker-compose pause [SERVICE…]

Pause a service container

16、docker-compose kill

docker-compose kill [options] [SERVICE…]

By sending the SIGKILL signal to forcibly stop the service container.
Support the -s parameter to specify the signal to be sent, for example, send the SIGINT signal through the following command:

docker-compose kill -s SIGINT

17、dokcer-compose config

docker-compose config [options]

Verify and view the compose file configuration.
Options include:
-resolve-image-digests mark the image tag as digest
-q, -quiet only verify the configuration, not output. When the configuration is correct, nothing will be output. When the file configuration is wrong, an error message will be output
-services print the service name, one
per line -volumes print the data volume name, one per line

18、docker-compose create

docker-compose create [options] [SERVICE…]

Create a container for the service.
Options include:
–force-recreate: re-create the container, even if the configuration and image are not changed, incompatible –no-recreate parameter
–no-recreate: if the container already exists, do not need to be recreated, incompatible –force-recreate parameter
–no -build: do not create a mirror, even if it is missing
-build: generate a mirror before creating the container

19、docker-compose exec

docker-compose exec [options] SERVICE COMMAND [ARGS…]

Options include:
-d Separate mode, run commands in the background.
-Privileged Get privileges.
-User USER specifies the user to run.
-T Disable the allocation of TTY, default docker-compose exec allocates TTY.
–Index=index, when a service has multiple containers, you can log in to any service under the service through this parameter, for example: docker-compose exec –index=1 web /bin/bash, the web service contains multiple containers

20、docker-compose port

docker-compose port [options] SERVICE PRIVATE_PORT

Display the public port mapped by a container port.
Options include:
-protocol=proto, specify the port protocol, TCP (default) or UDP
-index=index, if you agree to have multiple containers for the service, specify the serial number of the command object container (default is 1)

21、docker-compose push

docker-compose push [options] [SERVICE…]

The image on which the push service depends.
Options include:
--ignore-push-failures Ignore errors in the process of pushing the image

22、docker-compose stop

docker-compose stop [options] [SERVICE…]

Show the running process of each container.

23、docker-compose unpause

docker-compose unpause [SERVICE…]

Resume services that are in a suspended state.

24、docker-compose version

docker-compose version

Print version information.

Three, Docker-Compose template file

1. Introduction to Docker-Compose template file

Compose allows users to define a group of associated application containers as a project through a docker-compose.yml template file (YAML format).
The Compose template file is a YAML file that defines services, networks, and volumes. The default path of the Compose template file is docker-compose.yml in the current directory. You can use .yml or .yaml as the file extension.
The Docker-Compose standard template file should contain three parts: version, services, and networks. The most important part is services and networks.

version: '2'
services:
  web:
    image: dockercloud/hello-world
    ports:
      - 8080
    networks:
      - front-tier
      - back-tier

  redis:
    image: redis
    links:
      - web
    networks:
      - back-tier

  lb:
    image: dockercloud/haproxy
    ports:
      - 80:80
    links:
      - web
    networks:
      - front-tier
      - back-tier
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock 

networks:
  front-tier:
    driver: bridge
  back-tier:
    driver: bridge

Compose currently has three versions: Version 1, Version 2, Version 3. Compose distinguishes between Version 1 and Version 2 (Compose 1.6.0+, Docker Engine 1.10.0+). Version 2 supports more instructions. Version 1 will be deprecated in the future.

2、image

image is the image name or image ID of the specified service. If the image does not exist locally, Compose will try to pull the image.

services: 
    web: 
        image: hello-world

3、build

In addition to the specified image, the service can also be based on a Dockerfile. The build task is executed when starting with up. The build label is build, and the path to the folder where the Dockerfile is located can be specified. Compose will use the Dockerfile to automatically build the image, and then use the image to start the service container.
build: /path/to/build/dir
can also be a relative path, as long as the context is determined, the Dockerfile can be read.
build: ./dir
Set the context root directory, and then specify the Dockerfile based on this directory.

build:
  context: ../
  dockerfile: path/of/Dockerfile

The build is a directory, if you want to specify the Dockerfile file, you need to use the dockerfile tag to specify in the child tag of the build tag.
If you specify both the image and build tags, Compose will build the image and name the image the name specified by the image value.

4、context

The context option can be the file path of the Dockerfile or the URL linked to the git repository. When the provided value is a relative path, it will be resolved to the path relative to the composing file. This directory is also the context sent to the Docker daemon.

build:
  context: ./dir

5. Dockerfile is built
using dockerfile files, and the build path must be specified

build:
  context: .
  dockerfile: Dockerfile-alternate

The dockerfile instruction cannot be used with the image at the same time, otherwise Compose will not be sure which instruction to use to generate the final service image.

6、command

Use command to override the command executed by default after the container is started.

command: bundle exec thin -p 3000

7、container_name

Compose's container name format is: <project name><service name><serial number>
You can customize the project name and service name, but if you want to fully control the naming of the container, you can use the label to specify:

container_name: app

8、depends_on

When using Compose, the biggest advantage is that there are fewer startup commands, but generally the order in which the project container starts is required. If you start the container directly from top to bottom, it will inevitably fail to start due to container dependency issues. For example, if the application container is started when the database container is not started, the application container will exit because it cannot find the database. The depends_on tag is used to solve the problem of container dependency and startup sequence.

version: '2'
services:
  web:
    build: .
    depends_on:
      - db
      - redis
  redis:
    image: redis
  db:
    image: postgres

The container defined by the above YAML file will first start the redis and db services, and finally start the web service.

9、pid

pid: "host"
sets the PID mode to host PID mode, sharing the process namespace with the host system. Containers using pid tags will be able to access and manipulate the namespaces of other containers and hosts.

10、ports

ports are used to map the port label.
Use the HOST:CONTAINER format or just specify the port of the container, and the host will randomly map the port.

ports:
 - "3000"
 - "8000:8000"
 - "49100:22"
 - "127.0.0.1:8001:8001"

When using the HOST:CONTAINER format to map ports, if the container port used is less than 60, you may get an incorrect result, because YAML will parse the number format of xx:yy as hexadecimal. So it is recommended to use string format.

11、extra_hosts

Adding the label of the host name will add some records in the /etc/hosts file.

extra_hosts:
 - "somehost:162.242.195.82"
 - "otherhost:50.31.209.229"

Check the internal hosts of the container after startup:

162.242.195.82  somehost
50.31.209.229   otherhost

12、volumes

To mount a directory or an existing data volume container, you can directly use the [HOST:CONTAINER] format, or use the [HOST:CONTAINER:ro] format, the latter for the container, the data volume is read-only and can be valid Protect the host's file system.
Compose's data volume specified path can be a relative path, use. Or... to specify a relative directory.
The format of the data volume can be in the following forms:

volumes:
// Just specify a path, Docker will automatically create a data volume (this path is inside the container).

• /var/lib/mysql
  // Use absolute path to mount data volume
• /opt/data:/var/lib/mysql
  // The relative path centered on the Compose configuration file is mounted to the container as the data volume.
• ./cache:/tmp/cache
  // Use the user's relative path (~/ indicates the directory is /home/<user directory>/ or /root/).
• ~/configs:/etc/configs/:ro
  // An existing named data volume.
• datavolume:/var/lib/mysql
  If you do not use the path of the host, you can specify a volume_driver.
  volume_driver: mydriver

13、volumes_from

Mount its data volume from another service or container:

volumes_from:
   - service_name    
     - container_name

14、dns

Custom DNS server. It can be a value or a list.

dns：8.8.8.8
dns：
    - 8.8.8.8    
      - 9.9.9.9

15. dns_search
configures the DNS search domain. It can be a value or a list.

dns_search：example.com
dns_search：
    - domain1.example.com
    - domain2.example.com

16、entrypoint

There is an instruction in the Dockerfile called the ENTRYPOINT instruction, which is used to specify the access point.
Access points can be defined in docker-compose.yml, overriding the definition in Dockerfile:

entrypoint: /code/entrypoint.sh

17、env_file

A file dedicated to storing variables can be defined in docker-compose.yml.
If the configuration file is specified by docker-compose -f FILE, the path in env_file will use the configuration file path.
If a variable name conflicts with the environment directive, the latter shall prevail. The format is as follows:
env_file: .env
or set multiple according to docker-compose.yml:

env_file:
  - ./common.env
  - ./apps/web.env
  - /opt/secrets.env

If there is a build operation in the configuration file, the variable will not enter the build process.

18、cap_add

Increase the kernel capacity of the specified container (capacity).
Let the container have all the capabilities that can be specified:

cap_add:
    - ALL

19、cap_drop

Remove the kernel capacity of the specified container.
To remove the NET_ADMIN ability, you can specify:

cap_drop:
    - NET_ADMIN

20、cgroup_parent

Created a cgroup group named cgroups_1:
cgroup_parent: cgroups_1

21、devices

Specify the device mapping relationship, for example:

devices:
    - "/dev/ttyUSB1:/dev/ttyUSB0"

22、expose

The port is exposed, but not mapped to the host, and only accessible by connected services. Only the internal port can be specified as a parameter, as shown below:

expose:
    - "3000"
    - "8000"

23、extends

Expand based on other template files. For example, for the webapp service, a basic template file is defined as common.yml:

#common.yml
webapp:
    build: ./webapp
    environment:
        - DEBUG=false
        - SEND_EMAILS=false

Write a new development.yml file and use the webapp service in common.yml to expand:

#development.yml
web:
    extends:
        file: common.yml
        service: webapp
    ports:
        - "8000:8000"
    links:
        - db
    environment:
        - DEBUG=true
db:
    image: mysql

The latter will automatically inherit the webapp service and environment variable definitions in common.yml.
The limits of extends are as follows:
A. To avoid cyclic dependency.
B, extends will not inherit the container and data volume resources defined in links and volumes_from. It is
recommended to define only some images and environment variables that can be shared in the basic template, and specify them in the extended template. Application variables, links, data volumes and other information

24、external_links

The container linked to the outside of docker-compose.yml can be an external container that is not managed by Compose.

external_links:
    - redis_1
    - project_db_1:mysql
    - project_db_1:postgresql

25. Labels
add Docker metadata (metadata) information to the container. For example, you can add auxiliary information to the container:

labels：
    com.startupteam.description: "webapp for a strtup team"

26.
Links link to containers in other services. Use the service name (as an alias at the same time), or "service name: service alias" (such as SERVICE:ALIAS), for example:

links:
    - db
    - db:database
    - redis

The alias will be automatically created in /etc/hosts in the service container. E.g:

172.17.2.186  db
172.17.2.186  database
172.17.2.187  redis
27、log_driver

Specify the log driver type. Currently supports three log driver types:

log_driver: "json-file"
log_driver: "syslog"
log_driver: "none"

28、log_opt

Log-driven related parameters. E.g:

log_driver: "syslog"log_opt: 
    syslog-address: "tcp://192.168.0.42:123"

29、net

Set the network mode.

net: "bridge"
net: "none"
net: "host"

30、security_opt

Specify the default attributes (user, role, type, level, etc.) of the container template label mechanism. For example, to configure the user name and role name of the label:

security_opt:
    - label:user:USER
    - label:role:ROLE

31, environment variables

Environment variables can be used to configure the behavior of Docker-Compose.
COMPOSE_PROJECT_NAME
sets the project name added before each container started by Compose. The default is the name of the current working directory.
COMPOSE_FILE
sets the path of the docker-compose.yml template file. The default path is the current working directory.
DOCKER_HOST
sets the address of the Docker daemon. By default, unix:///var/run/docker.sock is used.
If the DOCKER_TLS_VERIFY setting is not empty, the interaction with the Docker daemon is performed through TLS.
DOCKER_CERT_PATH
configures the path of the verification (ca.pem, cert.pem and key.pem) files required for TLS communication. The default is ~/.docker.

Four, Docker-Compose template file example

1. Docker-compose template file writing

The docker-compose.yaml file is as follows:

version: '2'
services:
  web1:
    image: nginx
    ports: 
      - "6061:80"
    container_name: "web1"
    networks:
      - dev
  web2:
    image: nginx
    ports: 
      - "6062:80"
    container_name: "web2"
    networks:
      - dev
      - pro
  web3:
    image: nginx
    ports: 
      - "6063:80"
    container_name: "web3"
    networks:
      - pro

networks:
  dev:
    driver: bridge
  pro:
    driver: bridge

#volumes:

The docker-compose.yaml file specifies three web services.

2. Start the application

Create a webapp directory, copy the docker-compose.yaml file to the webapp directory, and use docker-compose to start the application.

docker-compose up -d

3. Service access

Access web1, web2, web3 services through a browser:

http://127.0.0.1:6061
http://127.0.0.1:6062
http://127.0.0.1:6063