How to customize the docker run command on Elastic Beanstalk?

Question

Here's the thing, I need to tell Docker to not containerize the container’s networking, because it needs to connect to a MongoDB that is inside a VPN (enterprise private DB).

There is a Docker command that let's me do exactly that: --net=host. Reference here.

So, for example, when running the container on my local machine, I will do something like:

docker run --rm -it --net=host [image-name]:[version] bash -il 

And that command will do the trick. Thanks to that, I can connect to the "private" MongoDB.

So, my question is: Is there a way customize the docker run command of a Single Docker Environment on Elastic Beanstalk so I can add the --net=host?

I have tried using the container_commands into the config.yml file to add that instruction there, but I don't think that does what I need, here is a snippet:

container_commands:   00-test_command:     command: bundle exec thin --net=host   01-networking-fix:     command: "docker run --rm -it --net=host [image-name]:[version] bash -il" 

Answer 1

I ended up fixing it with two container commands

container_commands:   00_fix_networking:     command: sed -i 's/docker run -d/docker run --net=host -d/' /opt/elasticbeanstalk/hooks/appdeploy/enact/00run.sh   01_fix_docker_ip:     command: sed -i 's/server $EB_CONFIG_NGINX_UPSTREAM_IP/server localhost/' /opt/elasticbeanstalk/hooks/appdeploy/enact/01flip.sh 

Update: I also had to fix the Upstart script. Unfortunately, I didn't write down what I did because I didn't end up needing to alter the docker run command. You would do a files directive for (I think) /etc/init/docker. AWS edits the Nginx configuration in the same manner as in 01flip.sh in that file as well.

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Explanation:

In the 64bit Amazon Linux 2015.03 v2.0.2 running Docker 1.7.1 platform version, the file you need to edit is /opt/elasticbeanstalk/hooks/appdeploy/enact/00run.sh. This file is now far more complex than Samar's version so I didn't want to put the actual contents in there. However, the change is basically the same. There's the line that starts with

docker run -d 

I fixed it with a container command:

container_commands:   00_fix_networking:     command: sed -i 's/docker run -d/docker run --net=host -d/' /opt/elasticbeanstalk/hooks/appdeploy/enact/00run.sh 

This successfully adds the --net=host argument but now there's another problem. The system ends up with an invalid Nginx directive. Using --net=host means that when you run docker inspect <container id> there is no IP address in the NetworkSettings. AWS uses this to create the server directive for Nginx and ends up generating server :<some port you chose> (before adding --net=host it would look like server <ip>:<port>). I needed to patch that file, too. It's generated in /opt/elasticbeanstalk/hooks/appdeploy/enact/01flip.sh.

01_fix_docker_ip:   command: sed -i 's/server $EB_CONFIG_NGINX_UPSTREAM_IP/server localhost/' /opt/elasticbeanstalk/hooks/appdeploy/enact/01flip.sh