Exposing multiple ports from Docker within Elastic

问题:

From reading the AWS documentation, it appears that when using Docker as the platform on Elastic Beanstalk (EB) (as opposed to Tomcat, etc.), only a single port can be exposed. I'm trying to understand why Amazon created this restriction -- seems that you now can't even serve both HTTP and HTTPS.

I'd like to use Docker as the container since it allows me to run several interconnected server processes within the same container, some of which require multiple ports (e.g. RTSP). Are there any workarounds for this kind of application, where say an RTSP and HTTP server can both be running within the same Docker container on EB?

回答1:

You could write an on-start config file for Elastic Beanstalk's LoadBalancer/ReversProxy to forward the additional ports to its EC2 instance(s). an example from Ben Delarre :

"Resources" : {
  "AWSEBLoadBalancerSecurityGroup": {
    "Type" : "AWS::EC2::SecurityGroup",
    "Properties" : {
      "GroupDescription" : "Enable 80 inbound and 8080 outbound",
      "VpcId": "vpc-un1que1d",
      "SecurityGroupIngress" : [ {
        "IpProtocol" : "tcp",
        "FromPort" : "80",
        "ToPort" : "80",
        "CidrIp" : "0.0.0.0/0"
      }],
      "SecurityGroupEgress": [ {
        "IpProtocol" : "tcp",
        "FromPort" : "8080",
        "ToPort" : "8080",
        "CidrIp" : "0.0.0.0/0"
      } ]
    }
  },
  "AWSEBLoadBalancer" : {
    "Type" : "AWS::ElasticLoadBalancing::LoadBalancer",
    "Properties" : {
      "Subnets": ["subnet-un1que1d2"],
      "Listeners" : [ {
        "LoadBalancerPort" : "80",
        "InstancePort" : "8080",
        "Protocol" : "HTTP"
      } ]
    }
  }
}

Ref:

• Customizing AWS EB's ENV http://docs.aws.amazon.com/elasticbeanstalk/latest/dg/environment-resources.html
• http://docs.aws.amazon.com/ElasticLoadBalancing/latest/DeveloperGuide/using-elb-listenerconfig-quickref.html

回答2:

Even though none of the documentation explains it, Single Container Docker Environment does support mapping multiple ports

{
    "AWSEBDockerrunVersion": "1",
    "Ports": [
        {
            "ContainerPort": "8080"
        },
        {
            "HostPort": "9000",
            "ContainerPort": "8090"
        }
    ]
}

With above configuration, port 8080 of docker will get mapped to host machines port 80 and port 8090 of docker will get mapped to host machine's port 9000.

To be more clear always the first port in the list will get mapped to host machine's port 80 and remaining will get mapped to specified hostPort (or) the same as container port in absence of host port.

回答3:

In its current form, the Docker support in Elastic Beanstalk is marginal at best. FWIW I wrote a blog post evaluating EB that touched on this. I found that in addition to your observation about ports, it's not possible to run multiple containers, nor to even customize the docker run command. Hopefully they'll extend support in a future update.