heroku - 在类似Heroku的云中扩展Web容器时处理嵌入式tomcat端口号的问题

Question

假设我有两个缩放比例如下的Web容器:

docker-compose scale web=2

Web容器执行如下(从Dockerfile中执行):

ENTRYPOINT [ "java", "-jar", "/app/my-jar-server-1.0.jar" ]

确保两个不同的嵌入式tomcat侦听不同端口的最佳策略是什么(例如，如果我要构建类似Heroku的基础架构: see foreman)？

换句话说，两个容器都将侦听同一端口，从而导致冲突。

理想情况下，我需要将请求循环到两个tomcat实例。我正在寻找工具和想法...

编辑1 :

这是我尝试过的:

从docker-compose.yml中:

loadbalancer:
  image: haproxy
  links:
      - web
  ports:
      - "8080:8080"
web:
  build: ./web

从./web/Dockerfile:

FROM java:8
ADD ./bignibou-server-1.0.jar /app/bignibou-server-1.0.jar
ADD ./spring-cloud.properties /app/spring-cloud.properties
ENV SPRING_CLOUD_PROPERTIESFILE=/app/spring-cloud.properties
ENV SPRING_PROFILES_ACTIVE=cloud
ENV SPRING_CLOUD_APP_NAME=bignibou
ENV CLEARDB_DATABASE_URL=mysql://root:root@localhost:3306/bignibou_dev
ENV REDISCLOUD_URL=redis://dummy:dummy@localhost:6379
ENV DYNO=dummy
EXPOSE 8080
ENTRYPOINT [ "java", "-jar", "/app/bignibou-server-1.0.jar" ]

这是我得到的:

loadbalancer_1 | [ALERT] 091/105717 (1) : Could not open configuration file /usr/local/etc/haproxy/haproxy.cfg : No such file or directory
dockertests_loadbalancer_1 exited with code 1
Gracefully stopping... (press Ctrl+C again to force)
Stopping dockertests_web_1...
Exception in thread Thread-1 (most likely raised during interpreter shutdown):
Traceback (most recent call last):
  File "/code/build/docker-compose/out00-PYZ.pyz/threading", line 552, in __bootstrap_inner
  File "/code/build/docker-compose/out00-PYZ.pyz/threading", line 505, in run
  File "/code/build/docker-compose/out00-PYZ.pyz/compose.cli.multiplexer", line 41, in _enqueue_output
  File "/code/build/docker-compose/out00-PYZ.pyz/compose.cli.log_printer", line 62, in _make_log_generator
  File "/code/build/docker-compose/out00-PYZ.pyz/compose.container", line 139, in wait
  File "/code/build/docker-compose/out00-PYZ.pyz/docker.client", line 999, in wait
  File "/code/build/docker-compose/out00-PYZ.pyz/docker.client", line 78, in _post
  File "/code/build/docker-compose/out00-PYZ.pyz/requests.sessions", line 425, in post
  File "/code/build/docker-compose/out00-PYZ.pyz/requests.sessions", line 383, in request
  File "/code/build/docker-compose/out00-PYZ.pyz/requests.sessions", line 486, in send
  File "/code/build/docker-compose/out00-PYZ.pyz/requests.adapters", line 374, in send
<type 'exceptions.AttributeError'>: 'NoneType' object has no attribute 'error'

edit 2 :忽略我的编辑1，我无法重现该问题。

但是，我能够在tomcat上成功启动两个实例，但尝试通过浏览器访问它们:

http://172.17.42.1:8080/

无济于事。有人可以帮忙吗？

Answer 1

最简单的方法(不沿领事路线走)是设置“loadbalancer”容器以了解您的“web”容器，例如:

web:
  image: tomcat

loadbalancer:
  image: haproxy
  links:
      - web
  ports:
      - "8080:8080"

请尝试docker-compose文档，特别是有关“链接”的部分: https://docs.docker.com/compose/yml/#links