一、使用Docker Compose必要性及定义
用容器运行一个服务,需要使用docker run命令。但如果我要运行多个服务呢?
假设我要运行一个web服务,还要运行一个db服务,那么是用一个容器运行,还是用多个容器运行呢?
一个容器运行多个服务会造成镜像的复杂度提高,docker倾向于一个容器运行一个应用。
那么复杂的架构就会需要很多的容器,并且需要它们之间有关联(容器之间的依赖和连接)就更复杂了。
这个复杂的问题需要解决,这就涉及到了**容器编排**的问题了。
- Compose
- 编排
- 是对多个容器进行启动和管理的方法
- 例如：LNMT，先启动MySQL,再启动Tomcat，最后启动Nginx
- 服务架构的演进
- 单体服务架构
- 分布式服务架构
- 微服务架构
- 超微服务架构
- 容器编排工具
- docker machine
- 在虚拟机中部署docker容器引擎的工具
- docker compose
- 是一个用于定义和运行多容器Docker的应用程序工具
- docker swarm
- 是Docker Host主机批量管理及资源调度管理工具
- mesos+marathon
- mesos 对计算机计算资源进行管理和调度
- marathon 服务发现及负载均衡的功能
- kubernetes
- google开源的容器编排工具
二、Docker Compose应用参考资料
网址 https://docs.docker.com/compose/
- yaml格式
https://yaml.org/
三、Docker Compose应用最佳实践步骤
3.1 概念
- 工程（project）
- 服务 (Service)
- 容器 (Container)
3.2 步骤
1.定义应用的Dockerfile文件，为了anywhere进行构建。
2.使用docker-compose.yaml定义一套服务，这套服务可以一起在一个隔离环境中运行。
3.使用docker-compose up就可以启动整套服务。
四、Docker Compose安装
# wget https://github.com/docker/compose/releases/download/v2.2.3/docker-compose-linux-x86_64
# mv docker-compose-linux-x86_64 /usr/bin/docker-compose
# chmod +x /usr/bin/docker-compose
# docker-compose version Docker Compose version v2.2.3
五、Docker Compose应用案例
运行Python语言开发的网站
5.1 网站文件准备
# mkdir flaskproject [root@localhost ~]# cd flaskproject/ [root@localhost flaskproject]#
[root@localhost flaskproject]# vim app.py
[root@localhost flaskproject]# cat 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)
[root@localhost flaskproject]# vim requirements.txt [root@localhost flaskproject]# cat requirements.txt flask redis
5.2 Dockerfile文件准备
[root@localhost flaskproject]# vim Dockerfile [root@localhost flaskproject]# cat 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 COPY . . CMD ["flask", "run"]
5.3 Compose文件准备
[root@localhost flaskproject]# vim docker-compose.yaml
[root@localhost flaskproject]# cat docker-compose.yaml
version: '3'
services:
web:
build: .
ports:
- "5000:5000"
redis:
image: "redis:alpine"
5.4 使用docker-compose up启动容器
[root@localhost flaskproject]# ls app.py docker-compose.yaml Dockerfile requirements.txt
[root@localhost flaskproject]# docker-compose up
输出： [+] Running 7/7 ⠿ redis Pulled 15.8s ⠿ 59bf1c3509f3 Pull complete 2.9s ⠿ 719adce26c52 Pull complete 3.0s ⠿ b8f35e378c31 Pull complete 5.8s ⠿ d034517f789c Pull complete 6.5s ⠿ 3772d4d76753 Pull complete 6.6s ⠿ 211a7f52febb Pull complete 6.8s Sending build context to Docker daemon 714B Step 1/9 : FROM python:3.7-alpine 3.7-alpine: Pulling from library/python 59bf1c3509f3: Already exists 07a400e93df3: Already exists bdabb07397e1: Already exists cd0af01c7b70: Already exists d0f18e022200: Already exists Digest: sha256:5a776e3b5336827faf7a1c3a191b73b5b2eef4cdcfe8b94f59b79cb749a2b5d8 Status: Downloaded newer image for python:3.7-alpine ---> e72b511ad78e Step 2/9 : WORKDIR /code ---> Running in 2b9d07bef719 Removing intermediate container 2b9d07bef719 ---> 7d39e96fadf1 Step 3/9 : ENV FLASK_APP app.py ---> Running in 9bcb28bd632a Removing intermediate container 9bcb28bd632a ---> 79f656a616d5 Step 4/9 : ENV FLASK_RUN_HOST 0.0.0.0 ---> Running in 8470c2dbd6c2 Removing intermediate container 8470c2dbd6c2 ---> e212ba688fcd Step 5/9 : RUN apk add --no-cache gcc musl-dev linux-headers ---> Running in 6e9ca0766bc8 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-r1) (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: 143 MiB in 49 packages Removing intermediate container 6e9ca0766bc8 ---> 273d4f04dfbc Step 6/9 : COPY requirements.txt requirements.txt ---> daf51c54e8ba Step 7/9 : RUN pip install -r requirements.txt ---> Running in 2aa2d30c5311 Collecting flask Downloading Flask-2.0.3-py3-none-any.whl (95 kB) Collecting redis Downloading redis-4.1.3-py3-none-any.whl (173 kB) Collecting Jinja2>=3.0 Downloading Jinja2-3.0.3-py3-none-any.whl (133 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-2.0.3-py3-none-any.whl (289 kB) Collecting deprecated>=1.2.3 Downloading Deprecated-1.2.13-py2.py3-none-any.whl (9.6 kB) Collecting packaging>=20.4 Downloading packaging-21.3-py3-none-any.whl (40 kB) Collecting importlib-metadata>=1.0 Downloading importlib_metadata-4.11.1-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 typing-extensions>=3.6.4 Downloading typing_extensions-4.1.1-py3-none-any.whl (26 kB) Collecting zipp>=0.5 Downloading zipp-3.7.0-py3-none-any.whl (5.3 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-3.0.7-py3-none-any.whl (98 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-2.0.3 click-8.0.3 deprecated-1.2.13 flask-2.0.3 importlib-metadata-4.11.1 itsdangerous-2.0.1 packaging-21.3 pyparsing-3.0.7 redis-4.1.3 typing-extensions-4.1.1 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 22.0.3 is available. You should consider upgrading via the '/usr/local/bin/python -m pip install --upgrade pip' command. Removing intermediate container 2aa2d30c5311 ---> dd8f52b132f8 Step 8/9 : COPY . . ---> b36938a26cf5 Step 9/9 : CMD ["flask", "run"] ---> Running in 260cbfa02959 Removing intermediate container 260cbfa02959 ---> fa04dfec6ff2 Successfully built fa04dfec6ff2 Successfully tagged flaskproject_web:latest Use 'docker scan' to run Snyk tests against images to find vulnerabilities and learn how to fix them [+] Running 3/3 ⠿ Network flaskproject_default Created 0.1s ⠿ Container flaskproject-redis-1 Created 0.1s ⠿ Container flaskproject-web-1 Created 0.1s Attaching to flaskproject-redis-1, flaskproject-web-1 flaskproject-redis-1 | 1:C 15 Feb 2022 14:14:21.696 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo flaskproject-redis-1 | 1:C 15 Feb 2022 14:14:21.696 # Redis version=6.2.6, bits=64, commit=00000000, modified=0, pid=1, just started flaskproject-redis-1 | 1:C 15 Feb 2022 14:14:21.696 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf flaskproject-redis-1 | 1:M 15 Feb 2022 14:14:21.697 * monotonic clock: POSIX clock_gettime flaskproject-redis-1 | 1:M 15 Feb 2022 14:14:21.698 * Running mode=standalone, port=6379. flaskproject-redis-1 | 1:M 15 Feb 2022 14:14:21.698 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128. flaskproject-redis-1 | 1:M 15 Feb 2022 14:14:21.698 # Server initialized flaskproject-redis-1 | 1:M 15 Feb 2022 14:14:21.698 # 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. flaskproject-redis-1 | 1:M 15 Feb 2022 14:14:21.698 * Ready to accept connections flaskproject-web-1 | * Serving Flask app 'app.py' (lazy loading) flaskproject-web-1 | * Environment: production flaskproject-web-1 | WARNING: This is a development server. Do not use it in a production deployment. flaskproject-web-1 | Use a production WSGI server instead. flaskproject-web-1 | * Debug mode: off flaskproject-web-1 | * Running on all addresses. flaskproject-web-1 | WARNING: This is a development server. Do not use it in a production deployment. flaskproject-web-1 | * Running on http://172.18.0.2:5000/ (Press CTRL+C to quit)
5.5 访问
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