使用Docker堆栈部署的微服务-WildFly，Java EE和Couchbase

关于微服务的资料很多，只是用谷歌搜索就可以了！几年前，我在比利时的Devoxx上发表了有关将单片重构为微服务的演讲，它得到了很好的评价：

该博客将展示Docker如何简化微服务的创建和关闭。

该博客中使用的所有代码都在github.com/arun-gupta/couchbase-javaee上。

使用撰写的微服务定义

Docker 1.13引入了Docker Compose v3 。语法上的更改很小，但主要区别是添加了deploy属性。此属性允许为容器指定副本，滚动更新和重新启动策略。

我们的微服务将使用预先部署的Java EE应用程序启动WldFly应用程序服务器。该应用程序将与Couchbase数据库对话以获取CRUD应用程序数据。

这是Compose定义：

version: '3'
services:web:image: arungupta/couchbase-javaee:travelenvironment:- COUCHBASE_URI=dbports:- 8080:8080- 9990:9990depends_on:- dbdb:image: arungupta/couchbase:travelports:- 8091:8091- 8092:8092 - 8093:8093 - 11210:11210

在此撰写文件中：

此Compose中的两个服务由名称db和web属性定义
使用image属性定义的每个服务的图像名称
arungupta/couchbase:travel图像将启动Couchbase服务器，使用Couchbase REST API对其进行配置，并使用〜32k JSON文档加载travel-sample存储桶。
arungupta/couchbase-javaee:travel映像启动WildFly并部署从https://github.com/arun-gupta/couchbase-javaee构建的应用程序WAR文件。如果要构建自己的映像，请克隆该项目。
envrionment属性定义了WildFly中部署的应用程序可访问的环境变量。 COUCHBASE_URI引用数据库服务。在https://github.com/arun-gupta/couchbase-javaee/blob/master/src/main/java/org/couchbase/sample/javaee/Database.java所示的应用程序代码中使用了此代码。
端口转发是使用ports属性实现的
Compose定义文件中的depends_on属性可确保容器启动顺序。但是应用程序级别的启动需要通过容器内运行的应用程序来确保。在我们的例子中，WildFly的启动速度非常快，但是要花几秒钟才能启动数据库。这意味着WildFly中部署的Java EE应用程序无法与数据库进行通信。这概述了构建微服务应用程序时的最佳实践：您必须进行防御性编码，并在应用程序初始化中确保依赖的微服务已启动，而无需假定启动顺序。这显示在https://github.com/arun-gupta/couchbase-javaee/blob/master/src/main/java/org/couchbase/sample/javaee/Database.java的数据库初始化代码中。它执行以下检查：
1. 铲斗存在
2. Couchbase的查询服务已启动并正在运行
3. 样品桶已满载

可以在单个主机上使用docker-compose up -d命令启动该应用程序。或使用docker stack deploy命令以群集模式运行的Docker引擎集群。

设置Docker Swarm模式

使用以下命令初始化Swarm模式：

docker swarm init

这将启动“群管理器”。默认情况下，管理者节点也是工作者，但可以配置为仅管理者。

使用命令docker info命令查找有关此单节点集群的一些信息：

Containers: 0Running: 0Paused: 0Stopped: 0
Images: 17
Server Version: 1.13.0
Storage Driver: overlay2Backing Filesystem: extfsSupports d_type: trueNative Overlay Diff: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:Volume: localNetwork: bridge host ipvlan macvlan null overlay
Swarm: activeNodeID: 92mydh0e09ba5hx3wtmcmvktzIs Manager: trueClusterID: v68ikyaff7rdxpaw1j0c9i60sManagers: 1Nodes: 1Orchestration:Task History Retention Limit: 5Raft:Snapshot Interval: 10000Number of Old Snapshots to Retain: 0Heartbeat Tick: 1Election Tick: 3Dispatcher:Heartbeat Period: 5 secondsCA Configuration:Expiry Duration: 3 monthsNode Address: 192.168.65.2Manager Addresses:192.168.65.2:2377
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 03e5862ec0d8d3b3f750e19fca3ee367e13c090e
runc version: 2f7393a47307a16f8cee44a37b262e8b81021e3e
init version: 949e6fa
Security Options:seccompProfile: default
Kernel Version: 4.9.5-moby
Operating System: Alpine Linux v3.5
OSType: linux
Architecture: x86_64
CPUs: 4
Total Memory: 1.952 GiB
Name: moby
ID: SGCM:KDRD:G3M7:PZHN:J4RL:VFFR:G2SR:EKD5:JV4J:RL3X:LF7T:XF6V
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): trueFile Descriptors: 31Goroutines: 124System Time: 2017-01-27T08:25:58.032295342ZEventsListeners: 1
No Proxy: *.local, 169.254/16
Username: arungupta
Registry: https://index.docker.io/v1/
Experimental: true
Insecure Registries:127.0.0.0/8
Live Restore Enabled: false

该集群有1个节点，即节点。

或者，可以使用Docker for AWS轻松设置多主机集群。

部署微服务

可以通过以下方式启动微服务：

docker stack deploy --compose-file=docker-compose.yml webapp

显示输出：

Creating network webapp_default
Creating service webapp_web
Creating service webapp_db

WildFly和Couchbase服务在此节点上启动。每个服务都有一个容器。如果在多个节点上启用了Swarm模式，则容器将分布在多个节点上。

创建一个新的覆盖网络。这允许不同主机上的多个容器相互通信。
使用docker docker service ls验证WildFly和Couchbase服务是否正在运行：

ID            NAME        MODE        REPLICAS  IMAGE
a9pkiziw3vgw  webapp_db   replicated  1/1       arungupta/couchbase:travel
hr5s6ue54kwj  webapp_web  replicated  1/1       arungupta/couchbase-javaee:travel

可以使用docker service logs -f webapp_web查看该服务的docker service logs -f webapp_web ：

webapp_web.1.wby0b04t7bap@moby    | =========================================================================
webapp_web.1.wby0b04t7bap@moby    |
webapp_web.1.wby0b04t7bap@moby    |   JBoss Bootstrap Environment
webapp_web.1.wby0b04t7bap@moby    |
webapp_web.1.wby0b04t7bap@moby    |   JBOSS_HOME: /opt/jboss/wildfly
webapp_web.1.wby0b04t7bap@moby    |
webapp_web.1.wby0b04t7bap@moby    |   JAVA: /usr/lib/jvm/java/bin/java
webapp_web.1.wby0b04t7bap@moby    |
webapp_web.1.wby0b04t7bap@moby    |   JAVA_OPTS:  -server -Xms64m -Xmx512m -XX:MetaspaceSize=96M -XX:MaxMetaspaceSize=256m -Djava.net.preferIPv4Stack=true -Djboss.modules.system.pkgs=org.jboss.byteman -Djava.awt.headless=true
webapp_web.1.wby0b04t7bap@moby    |
webapp_web.1.wby0b04t7bap@moby    | =========================================================================. . .webapp_web.1.wby0b04t7bap@moby    | 23:14:15,811 INFO  [org.jboss.as.server] (ServerService Thread Pool -- 34) WFLYSRV0010: Deployed "airlines.war" (runtime-name : "airlines.war")
webapp_web.1.wby0b04t7bap@moby    | 23:14:16,076 INFO  [org.jboss.as] (Controller Boot Thread) WFLYSRV0060: Http management interface listening on http://127.0.0.1:9990/management
webapp_web.1.wby0b04t7bap@moby    | 23:14:16,077 INFO  [org.jboss.as] (Controller Boot Thread) WFLYSRV0051: Admin console listening on http://127.0.0.1:9990
webapp_web.1.wby0b04t7bap@moby    | 23:14:16,077 INFO  [org.jboss.as] (Controller Boot Thread) WFLYSRV0025: WildFly Full 10.1.0.Final (WildFly Core 2.2.0.Final) started in 98623ms - Started 443 of 691 services (404 services are lazy, passive or on-demand)

确保等待最后一条日志语句显示。

存取微服务

从微服务获取10家航空公司：

curl -v http://localhost:8080/airlines/resources/airline

结果显示为：

*   Trying ::1...
* Connected to localhost (::1) port 8080 (#0)
> GET /airlines/resources/airline HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.43.0
> Accept: */*
>
< HTTP/1.1 200 OK
< Connection: keep-alive
< X-Powered-By: Undertow/1
< Server: WildFly/10
< Content-Type: application/octet-stream
< Content-Length: 1402
< Date: Fri, 03 Feb 2017 17:02:45 GMT
<
* Connection #0 to host localhost left intact
[{"travel-sample":{"country":"United States","iata":"Q5","callsign":"MILE-AIR","name":"40-Mile Air","icao":"MLA","id":10,"type":"airline"}}, {"travel-sample":{"country":"United States","iata":"TQ","callsign":"TXW","name":"Texas Wings","icao":"TXW","id":10123,"type":"airline"}}, {"travel-sample":{"country":"United States","iata":"A1","callsign":"atifly","name":"Atifly","icao":"A1F","id":10226,"type":"airline"}}, {"travel-sample":{"country":"United Kingdom","iata":null,"callsign":null,"name":"Jc royal.britannica","icao":"JRB","id":10642,"type":"airline"}}, {"travel-sample":{"country":"United States","iata":"ZQ","callsign":"LOCAIR","name":"Locair","icao":"LOC","id":10748,"type":"airline"}}, {"travel-sample":{"country":"United States","iata":"K5","callsign":"SASQUATCH","name":"SeaPort Airlines","icao":"SQH","id":10765,"type":"airline"}}, {"travel-sample":{"country":"United States","iata":"KO","callsign":"ACE AIR","name":"Alaska Central Express","icao":"AER","id":109,"type":"airline"}}, {"travel-sample":{"country":"United Kingdom","iata":"5W","callsign":"FLYSTAR","name":"Astraeus","icao":"AEU","id":112,"type":"airline"}}, {"travel-sample":{"country":"France","iata":"UU","callsign":"REUNION","name":"Air Austral","icao":"REU","id":1191,"type":"airline"}}, {"travel-sample":{"country":"France","iata":"A5","callsign":"AIRLINAIR","name":"Airlinair","icao":"RLA","id":1203,"type":"airline"}}]

Docker for Java Developers研讨会是一个自定进度的动手实验，它使您可以轻松地开始使用Docker。

获取单个资源：

curl -v http://localhost:8080/airlines/resources/airline/137

创建一个新资源：

curl -v -H "Content-Type: application/json" -X POST -d '{"country":"France","iata":"A5","callsign":"AIRLINAIR","name":"Airlinair","icao":"RLA","type":"airline"}' http://localhost:8080/airlines/resources/airline

更新资源：

curl -v -H "Content-Type: application/json" -X PUT -d '{"country":"France","iata":"A5","callsign":"AIRLINAIR","name":"Airlin Air","icao":"RLA","type":"airline","id": "19810"}' http://localhost:8080/airlines/resources/airline/19810

删除资源：

curl -v -X DELETE http://localhost:8080/airlines/resources/airline/19810

每个命令的详细输出在github.com/arun-gupta/couchbase-javaee上。

删除微服务

可以使用命令docker stack rm webapp删除微服务：

Removing service webapp_web
Removing service webapp_db
Removing network webapp_default

想要开始使用Couchbase吗？查看Couchbase入门套件。

想更多地了解如何在容器中运行Couchbase？

容器上的Couchbase
Couchbase论坛
Couchbase开发人员门户
@couchhasedev和@couchbase

翻译自: https://www.javacodegeeks.com/2017/02/microservice-using-docker-stack-deploy-wildfly-java-ee-couchbase.html