前言
Compose是一个定义和运行多个Docker应用的工具，用一个YAML（dockder-compose.yml）文件就能配置我们的应用。然后用一个简单命令就能启动所有的服务。Compose编排Docker服务的优势是在单机测试场景，因为Compose的安装简单，开箱即用，yaml的定义也复用了Dockerfile的语法。但是集群中容器编排服务还是推荐K8S或者Mesos+Marathon这样的编排调度系统。
演示环境
$ uname -a Darwin 18.6.0 Darwin Kernel Version 18.6.0: Thu Apr 25 23:16:27 PDT 2019; root:xnu-4903.261.4~2/RELEASE_X86_64 x86_64 $ docker version Client: Docker Engine - Community Version: 18.09.2 API version: 1.39 Go version: go1.10.8 Git commit: 6247962 Built: Sun Feb 10 04:12:39 2019 OS/Arch: darwin/amd64 Experimental: false
示例
老规矩，我会先用一个示例来引入接下来要讲解的内容。下面我将演示用Docker Compose一键运行集中式日志系统ELK。ELK是一套日志收集方案，是三款软件产品的名字缩写，Elasticsearch，Logstash 和 Kibana。
ELK的docker-compose.yml 来自github仓库docker-elk。docker-compose.yml的内容如下：
version: '2' services: elasticsearch: build: context: elasticsearch/ args: ELK_VERSION: $ELK_VERSION volumes: - ./elasticsearch/config/elasticsearch.yml:/usr/share/elasticsearch/config/elasticsearch.yml:ro ports: - "9200:9200" - "9300:9300" environment: ES_JAVA_OPTS: "-Xmx256m -Xms256m" ELASTIC_PASSWORD: changeme networks: - elk logstash: build: context: logstash/ args: ELK_VERSION: $ELK_VERSION volumes: - ./logstash/config/logstash.yml:/usr/share/logstash/config/logstash.yml:ro - ./logstash/pipeline:/usr/share/logstash/pipeline:ro ports: - "5000:5000" - "9600:9600" environment: LS_JAVA_OPTS: "-Xmx256m -Xms256m" networks: - elk depends_on: - elasticsearch kibana: build: context: kibana/ args: ELK_VERSION: $ELK_VERSION volumes: - ./kibana/config/kibana.yml:/usr/share/kibana/config/kibana.yml:ro ports: - "5601:5601" networks: - elk depends_on: - elasticsearch networks: elk: driver: bridge
进入到docker-compose.yml目录，通过docker-compose up -d 这条命令就能启动一个本地环境的ELK系统：
$ docker-compose up -d Building kibana Step 1/2 : ARG ELK_VERSION Step 2/2 : FROM docker.elastic.co/kibana/kibana:${ELK_VERSION} 7.1.1: Pulling from kibana/kibana 8ba884070f61: Already exists 3dd92e31d54b: Downloading [====================> ] 18.31MB/44.81MB 47d37f21fc3a: Pull complete 97eef8537832: Pull complete 151d3d8996bb: Pull complete 003e03312113: Pull complete 0fbb6a4413a0: Pull complete c455cf619e40: Pull complete Digest: sha256:fbf558c6df18500f00ab9c1e1ce2d566ad2c1800d023106e4a4a85274b0d40cd Status: Downloaded newer image for docker.elastic.co/kibana/kibana:7.1.1 ---> 67f17df6ca3e Successfully built 67f17df6ca3e Successfully tagged docker-elk_kibana:latest WARNING: Image for service kibana was built because it did not already exist. To rebuild this image you must use `docker-compose build` or `docker-compose up --build`. Creating docker-elk_elasticsearch_1 ... done Creating docker-elk_kibana_1 ... done Creating docker-elk_logstash_1 ... done Attaching to docker-elk_elasticsearch_1, docker-elk_kibana_1, docker-elk_logstash_1 $ docker-compose ps Name Command State Ports ------------------------------------------------------------------------------------------------------------------------------ docker-elk_elasticsearch_1 /usr/local/bin/docker-entr ... Up 0.0.0.0:9200->9200/tcp, 0.0.0.0:9300->9300/tcp docker-elk_kibana_1 /usr/local/bin/kibana-docker Up 0.0.0.0:5601->5601/tcp docker-elk_logstash_1 /usr/local/bin/docker-entr ... Up 0.0.0.0:5000->5000/tcp, 5044/tcp, 0.0.0.0:9600->9600/tcp
访问kibana页面：
如果传统物理进程搭建ELK系统，首先要下载和安装Java JDK，下载ELK的版本，然后安装Elasticsearch，Logstash 和 Kibana。这整一套下来没有半天根本搞不定，现在集成到docker-compose只需要一条命令docker-compose up就能运行起来。所以利用docker-compose可以快速搭建本地测试环境，大大提高开发效率。相对于使用docker run这样的方式一个个起停容器，docker-compose提供了一个容器编排的服务，定义一组容器的起停依赖关系。也可以通过docker-compose stop logstash 来停止单一的logstash等服务。
详细说明
通过上面的例子我们已经掌握了Docker Comopose的起停等简单用法，那么Docker Compose一共有多少种用法呢，我们可以通过--help得到答案：
$ docker-compose --help Define and run multi-container applications with Docker. Usage: docker-compose [-f <arg>...] [options] [COMMAND] [ARGS...] docker-compose -h|--help Options: -f, --file FILE Specify an alternate compose file (default: docker-compose.yml) -p, --project-name NAME Specify an alternate project name (default: directory name) --verbose Show more output --log-level LEVEL Set log level (DEBUG, INFO, WARNING, ERROR, CRITICAL) --no-ansi Do not print ANSI control characters -v, --version Print version and exit -H, --host HOST Daemon socket to connect to --tls Use TLS; implied by --tlsverify --tlscacert CA_PATH Trust certs signed only by this CA --tlscert CLIENT_CERT_PATH Path to TLS certificate file --tlskey TLS_KEY_PATH Path to TLS key file --tlsverify Use TLS and verify the remote --skip-hostname-check Don't check the daemon's hostname against the name specified in the client certificate --project-directory PATH Specify an alternate working directory (default: the path of the Compose file) --compatibility If set, Compose will attempt to convert deploy keys in v3 files to their non-Swarm equivalent Commands: build Build or rebuild services bundle Generate a Docker bundle from the Compose file config Validate and view the Compose file create Create services down Stop and remove containers, networks, images, and volumes events Receive real time events from containers exec Execute a command in a running container help Get help on a command images List images kill Kill containers logs View output from containers pause Pause services port Print the public port for a port binding ps List containers pull Pull service images push Push service images restart Restart services rm Remove stopped containers run Run a one-off command scale Set number of containers for a service start Start services stop Stop services top Display the running processes unpause Unpause services up Create and start containers version Show the Docker-Compose version information
-f 指定compose文件，不是必须项，如果没有指定就变量当前路径或者父目录的docker-compose.yml文件。
-p 指定项目名称, 默认是目录名，例如例子中默认的docker-elk。
-v 显示Docker Compose版本。
--tls* 是加密证书相关选项。本机环境一般用不上。
build 创建容器服务，例如用Dockerfile build镜像。
ps 显示所有容器。
pull 拉取服务镜像。
push 推送服务镜像。
start 启动服务。
stop 停止服务。
up 创建和启动容器服务。相当于build（or pull）和start。
version 显示Docker Compose版本信息。
$ docker-compose version docker-compose version 1.23.2, build 1110ad01 docker-py version: 3.6.0 CPython version: 3.6.6 OpenSSL version: OpenSSL 1.1.0h 27 Mar 2018 $ docker-compose stop logstash Stopping docker-elk_logstash_1 ... done $ docker-compose ps Name Command State Ports --------------------------------------------------------------------------------------------------------------------- docker-elk_elasticsearch_1 /usr/local/bin/docker-entr ... Up 0.0.0.0:9200->9200/tcp, 0.0.0.0:9300->9300/tcp docker-elk_kibana_1 /usr/local/bin/kibana-docker Up 0.0.0.0:5601->5601/tcp docker-elk_logstash_1 /usr/local/bin/docker-entr ... Exit 0 $ docker-compose start logstash Starting logstash ... done $ docker-compose ps Name Command State Ports ------------------------------------------------------------------------------------------------------------------------------ docker-elk_elasticsearch_1 /usr/local/bin/docker-entr ... Up 0.0.0.0:9200->9200/tcp, 0.0.0.0:9300->9300/tcp docker-elk_kibana_1 /usr/local/bin/kibana-docker Up 0.0.0.0:5601->5601/tcp docker-elk_logstash_1 /usr/local/bin/docker-entr ... Up 0.0.0.0:5000->5000/tcp, 5044/tcp, 0.0.0.0:9600->9600/tcp
总结
文章用一键运行ELK系统演示了Docker Compose搭建环境的高效性，然后详细介绍了Docker Compose的大部分选型的含义和用法。