简介
使用 Docker 的时候，定义 Dockerfile 文件，然后使用 docker build、docker run 等命令操作容器。
然而微服务架构的应用系统一般包含若干个微服务，每个微服务一般都会部署多个实例，如果每个微服务都要手动启停，这样效率很低，也不方便管理。
使用 Docker Compose 可以轻松、高效的管理容器，它是一个用于定义和运行多容器 Docker 的应用程序工具。
yaml 官方示例
https://docs.docker.com/compose/compose-file/compose-file-v3/#compose-file-structure-and-examples
version: "3.9"
services:
redis:
image: redis:alpine
ports:
- "6379"
networks:
- frontend
deploy:
replicas: 2
update_config:
parallelism: 2
delay: 10s
restart_policy:
condition: on-failure
db:
image: postgres:9.4
volumes:
- db-data:/var/lib/postgresql/data
networks:
- backend
deploy:
placement:
max_replicas_per_node: 1
constraints:
- "node.role==manager"
vote:
image: dockersamples/examplevotingapp_vote:before
ports:
- "5000:80"
networks:
- frontend
depends_on:
- redis
deploy:
replicas: 2
update_config:
parallelism: 2
restart_policy:
condition: on-failure
result:
image: dockersamples/examplevotingapp_result:before
ports:
- "5001:80"
networks:
- backend
depends_on:
- db
deploy:
replicas: 1
update_config:
parallelism: 2
delay: 10s
restart_policy:
condition: on-failure
worker:
image: dockersamples/examplevotingapp_worker
networks:
- frontend
- backend
deploy:
mode: replicated
replicas: 1
labels: [APP=VOTING]
restart_policy:
condition: on-failure
delay: 10s
max_attempts: 3
window: 120s
placement:
constraints:
- "node.role==manager"
visualizer:
image: dockersamples/visualizer:stable
ports:
- "8080:8080"
stop_grace_period: 1m30s
volumes:
- "/var/run/docker.sock:/var/run/docker.sock"
deploy:
placement:
constraints:
- "node.role==manager"
networks:
frontend:
backend:
volumes:
db-data:
depends_on：依赖关系，如 web 依赖 redis 和 db，通过 depends_on 表明关系。
version: "3.9"
services:
web:
build: .
depends_on:
- db
- redis
redis:
image: redis
db:
image: postgres
安装
Docker Compose 是 Docker 的一个开源项目，目前托管到了 GitHub，需要前往 GitHub 下载。
sudo curl -L "https://github.com/docker/compose/releases/download/2.2.3/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
chmod +x /usr/local/bin/docker-compose
由于存放在GitHub，不太稳定。
推荐使用 道客 提供的 Docker 极速下载 进行安装。
curl -L https://get.daocloud.io/docker/compose/releases/download/v2.2.3/docker-compose-`uname -s`-`uname -m` > /usr/local/bin/docker-compose
chmod +x /usr/local/bin/docker-compose
安装
[root@sail ~]# curl -L https://get.daocloud.io/docker/compose/releases/download/v2.2.3/docker-compose-`uname -s`-`uname -m` > /usr/local/bin/docker-compose
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 423 100 423 0 0 394 0 0:00:01 0:00:01 --:--:-- 394
100 23.5M 100 23.5M 0 0 8670k 0 0:00:02 0:00:02 --:--:-- 20.3M
[root@sail ~]# cd /usr/local/bin/
[root@sail bin]# ls
docker-compose
这样即表示安装成功。
授权
[root@sail ~]# chmod +x /usr/local/bin/docker-compose
[root@sail ~]#
查看版本
docker-compose version
[root@sail bin]# docker-compose version
Docker Compose version v2.2.3
至此，Docker Compose 安装完成。
卸载
rm /usr/local/bin/docker-compose
由于 Linux 一切皆文件，删除此文件夹即可完成 Docker Compose 的卸载。
使用
构建
创建项目目录
[root@sail sail]# mkdir docker-compose
[root@sail sail]# cd docker-compose
[root@sail docker-compose]#
创建 app.py
[root@sail docker-compose]# vim app.py
import time
import redis
from flask import Flask
app = Flask(__name__)
cache = redis.Redis(host='redis', port=6379)
def get_hit_count():
retries = 5
while True:
try:
return cache.incr('hits')
except redis.exceptions.ConnectionError as exc:
if retries == 0:
raise exc
retries -= 1
time.sleep(0.5)
@app.route('/')
def hello():
count = get_hit_count()
return 'Hello World! I have been seen {} times.\n'.format(count)
redis 是应用容器中 redis 容器的主机名，在同一网络下可以通过服务名访问，端口默认 6379。
创建 requirements.txt
[root@sail docker-compose]# vim requirements.txt
[root@sail docker-compose]# cat requirements.txt
flask
redis
创建 Dockerfile
[root@sail docker-compose]# vim Dockerfile
FROM python:3.7-alpine
WORKDIR /code
ENV FLASK_APP=app.py
ENV FLASK_RUN_HOST=0.0.0.0
RUN apk add --no-cache gcc musl-dev linux-headers
COPY requirements.txt requirements.txt
RUN pip install -r requirements.txt
EXPOSE 5000
COPY . .
CMD ["flask", "run"]
创建 docker-compose.yml
[root@sail docker-compose]# vim docker-compose.yml
version: "3.3"
services:
web:
build: .
ports:
- "5000:5000"
redis:
image: "redis:alpine"
这个文件定义了两个服务：web 和 redis。
启动
docker-compose up
运行应用
在项目目录中，运行 docker-compose up 来启动应用程序。
第一次启动需要安装很多环境，比较缓慢。
[root@sail docker-compose]# docker-compose up
[+] Running 7/7
⠿ redis Pulled 14.1s
⠿ 59bf1c3509f3 Pull complete 3.0s
⠿ 719adce26c52 Pull complete 3.1s
⠿ b8f35e378c31 Pull complete 3.3s
⠿ d034517f789c Pull complete 9.0s
⠿ 3772d4d76753 Pull complete 9.0s
⠿ 211a7f52febb Pull complete 9.1s
Sending build context to Docker daemon 725B
Step 1/10 : FROM python:3.7-alpine
3.7-alpine: Pulling from library/python
59bf1c3509f3: Already exists
8786870f2876: Pull complete
45d4696938d0: Pull complete
ef84af58b2c5: Pull complete
c3c9b71b9a69: Pull complete
Digest: sha256:d64e0124674d64e78cc9d7378a1130499ced66a7a00db0521d0120a2e88ac9e4
Status: Downloaded newer image for python:3.7-alpine
---> a1034fd13493
Step 2/10 : WORKDIR /code
---> Running in e23e4b173abf
Removing intermediate container e23e4b173abf
---> 41eb64157cfc
Step 3/10 : ENV FLASK_APP=app.py
---> Running in cdefb769398d
Removing intermediate container cdefb769398d
---> ab741ac5cb17
Step 4/10 : ENV FLASK_RUN_HOST=0.0.0.0
---> Running in 4976c1da428c
Removing intermediate container 4976c1da428c
---> 5a5c24d67db6
Step 5/10 : RUN apk add --no-cache gcc musl-dev linux-headers
---> Running in 53043bd38e33
fetch https://dl-cdn.alpinelinux.org/alpine/v3.15/main/x86_64/APKINDEX.tar.gz
fetch https://dl-cdn.alpinelinux.org/alpine/v3.15/community/x86_64/APKINDEX.tar.gz
(1/13) Installing libgcc (10.3.1_git20211027-r0)
(2/13) Installing libstdc++ (10.3.1_git20211027-r0)
(3/13) Installing binutils (2.37-r3)
(4/13) Installing libgomp (10.3.1_git20211027-r0)
(5/13) Installing libatomic (10.3.1_git20211027-r0)
(6/13) Installing libgphobos (10.3.1_git20211027-r0)
(7/13) Installing gmp (6.2.1-r0)
(8/13) Installing isl22 (0.22-r0)
(9/13) Installing mpfr4 (4.1.0-r0)
(10/13) Installing mpc1 (1.2.1-r0)
(11/13) Installing gcc (10.3.1_git20211027-r0)
(12/13) Installing linux-headers (5.10.41-r0)
(13/13) Installing musl-dev (1.2.2-r7)
Executing busybox-1.34.1-r3.trigger
OK: 139 MiB in 48 packages
Removing intermediate container 53043bd38e33
---> 73e9550df596
Step 6/10 : COPY requirements.txt requirements.txt
---> c5a73d6f1fe1
Step 7/10 : RUN pip install -r requirements.txt
---> Running in 826790d0bfbb
Collecting flask
Downloading Flask-2.0.2-py3-none-any.whl (95 kB)
Collecting redis
Downloading redis-4.1.0-py3-none-any.whl (171 kB)
Collecting itsdangerous>=2.0
Downloading itsdangerous-2.0.1-py3-none-any.whl (18 kB)
Collecting click>=7.1.2
Downloading click-8.0.3-py3-none-any.whl (97 kB)
Collecting Werkzeug>=2.0
Downloading Werkzeug-2.0.2-py3-none-any.whl (288 kB)
Collecting Jinja2>=3.0
Downloading Jinja2-3.0.3-py3-none-any.whl (133 kB)
Collecting packaging>=21.3
Downloading packaging-21.3-py3-none-any.whl (40 kB)
Collecting deprecated>=1.2.3
Downloading Deprecated-1.2.13-py2.py3-none-any.whl (9.6 kB)
Collecting importlib-metadata>=1.0
Downloading importlib_metadata-4.10.0-py3-none-any.whl (17 kB)
Collecting wrapt<2,>=1.10
Downloading wrapt-1.13.3-cp37-cp37m-musllinux_1_1_x86_64.whl (78 kB)
Collecting zipp>=0.5
Downloading zipp-3.7.0-py3-none-any.whl (5.3 kB)
Collecting typing-extensions>=3.6.4
Downloading typing_extensions-4.0.1-py3-none-any.whl (22 kB)
Collecting MarkupSafe>=2.0
Downloading MarkupSafe-2.0.1-cp37-cp37m-musllinux_1_1_x86_64.whl (30 kB)
Collecting pyparsing!=3.0.5,>=2.0.2
Downloading pyparsing-3.0.6-py3-none-any.whl (97 kB)
Installing collected packages: zipp, typing-extensions, wrapt, pyparsing, MarkupSafe, importlib-metadata, Werkzeug, packaging, Jinja2, itsdangerous, deprecated, click, redis, flask
Successfully installed Jinja2-3.0.3 MarkupSafe-2.0.1 Werkzeug-2.0.2 click-8.0.3 deprecated-1.2.13 flask-2.0.2 importlib-metadata-4.10.0 itsdangerous-2.0.1 packaging-21.3 pyparsing-3.0.6 redis-4.1.0 typing-extensions-4.0.1 wrapt-1.13.3 zipp-3.7.0
WARNING: Running pip as the 'root' user can result in broken permissions and conflicting behaviour with the system package manager. It is recommended to use a virtual environment instead: https://pip.pypa.io/warnings/venv
WARNING: You are using pip version 21.2.4; however, version 21.3.1 is available.
You should consider upgrading via the '/usr/local/bin/python -m pip install --upgrade pip' command.
Removing intermediate container 826790d0bfbb
---> c1483947fad2
Step 8/10 : EXPOSE 5000
---> Running in cd59e0408b47
Removing intermediate container cd59e0408b47
---> 05c632dea80d
Step 9/10 : COPY . .
---> 8c89b910e366
Step 10/10 : CMD ["flask", "run"]
---> Running in 1d9d071fee96
Removing intermediate container 1d9d071fee96
---> de4639486b50
Successfully built de4639486b50
Successfully tagged docker-compose_web:latest
Use 'docker scan' to run Snyk tests against images to find vulnerabilities and learn how to fix them
[+] Running 3/3
⠿ Network docker-compose_default Created 0.3s
⠿ Container docker-compose-redis-1 Created 0.0s
⠿ Container docker-compose-web-1 Created 0.0s
Attaching to docker-compose-redis-1, docker-compose-web-1
docker-compose-redis-1 | 1:C 07 Jan 2022 08:36:26.687 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
docker-compose-redis-1 | 1:C 07 Jan 2022 08:36:26.687 # Redis version=6.2.6, bits=64, commit=00000000, modified=0, pid=1, just started
docker-compose-redis-1 | 1:C 07 Jan 2022 08:36:26.687 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf
docker-compose-redis-1 | 1:M 07 Jan 2022 08:36:26.687 * monotonic clock: POSIX clock_gettime
docker-compose-redis-1 | 1:M 07 Jan 2022 08:36:26.688 * Running mode=standalone, port=6379.
docker-compose-redis-1 | 1:M 07 Jan 2022 08:36:26.688 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
docker-compose-redis-1 | 1:M 07 Jan 2022 08:36:26.688 # Server initialized
docker-compose-redis-1 | 1:M 07 Jan 2022 08:36:26.688 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
docker-compose-redis-1 | 1:M 07 Jan 2022 08:36:26.688 * Ready to accept connections
docker-compose-web-1 | * Serving Flask app 'app.py' (lazy loading)
docker-compose-web-1 | * Environment: production
docker-compose-web-1 | WARNING: This is a development server. Do not use it in a production deployment.
docker-compose-web-1 | Use a production WSGI server instead.
docker-compose-web-1 | * Debug mode: off
docker-compose-web-1 | * Running on all addresses.
docker-compose-web-1 | WARNING: This is a development server. Do not use it in a production deployment.
docker-compose-web-1 | * Running on http://172.18.0.2:5000/ (Press CTRL+C to quit)
查看镜像
[root@sail docker-compose]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
docker-compose_web latest 6df8b78250a1 44 seconds ago 185MB
redis alpine 3900abf41552 5 weeks ago 32.4MB
python 3.7-alpine a1034fd13493 5 weeks ago 41.8MB
启动 Docker Compose 时，会自动拉取需要的镜像。
查看容器
[root@sail docker-compose]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
78a6f8b03a49 docker-compose_web "flask run" 8 minutes ago Up 8 minutes 0.0.0.0:5000->5000/tcp docker-compose-web-1
b4da6da4364f redis:alpine "docker-entrypoint.s…" 8 minutes ago Up 8 minutes 6379/tcp docker-compose-redis-1
可以看到容器命名都带有数字，是因为需要集群管理，数字代表副本序号。
查看网络
[root@sail docker-compose]# docker network ls
NETWORK ID NAME DRIVER SCOPE
b89f719e94e0 bridge bridge local
619a5845a105 docker-compose_default bridge local
28d77e958643 host host local
801fbbe1b38c mynet bridge local
c3ff850e96f0 none null local
项目中的内容都在同个网络下。
访问测试
[root@sail docker-compose]# curl localhost:5000
Hello World! I have been seen 1 times.
[root@sail docker-compose]# curl localhost:5000
Hello World! I have been seen 2 times.
[root@sail docker-compose]# curl localhost:5000
Hello World! I have been seen 3 times.
至此，Docker Compose 启动完成。
停止
docker-compose stop
示例
[root@sail docker-compose]# docker-compose stop
[+] Running 2/2
⠿ Container docker-compose-redis-1 Stopped 0.2s
⠿ Container docker-compose-web-1 Stopped
停止并删除容器和网络
docker-compose down
示例
[root@sail docker-compose]# docker-compose down
[+] Running 3/3
⠿ Container docker-compose-web-1 Removed 10.2s
⠿ Container docker-compose-redis-1 Removed 0.2s
⠿ Network docker-compose_default Removed
[root@sail docker-compose]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
[root@sail docker-compose]# docker network ls
NETWORK ID NAME DRIVER SCOPE
b89f719e94e0 bridge bridge local
28d77e958643 host host local
801fbbe1b38c mynet bridge local
c3ff850e96f0 none null local
可以看出，容器和网络都被删除了。
更多配置
https://docs.docker.com/compose/compose-file/compose-file-v3/#compose-file-structure-and-examples