[BOUNTY-2] Add NAT Docker Support

[matkt]

Signed-off-by: Karim TAAM karim.t2am@gmail.com

PR description

The goal of this work is to offer developers a consistent API for performing NAT tasks, and add support for Docker’s NAT implementation when Pantheon is being run from a Docker container.

Here is a proposal for the bounty allowing to detect the Docker environment automatically.

• Properly detects when Pantheon is being run inside a docker container.

Besu will automatically detect that the client is in a docker.

• Interacts with Docker APIs, as needed, to determine external IP address and exposed ports.

There is no method to detect the port mapping and the host IP.

There is host.docker.internal which is created by docker and which allows to recover the internal IP used by the host(https://docs.docker.com/docker-for-windows/networking/) but this is not the external IP. In addition we can have several layers between the real external IP address and the besu client (docker, box, etc.)
The port mapping is also not accessible from the container. There are methods but it looks more like a hack than a real solution (https://stackoverflow.com/questions/32444612/how-to-get-the-mapped-port-on-host-from-a-docker-container)

I suggest that if the client detects that it is launched in a docker it will look for :

• the IP address of a host, given a specific hostname (HOST_IP).
• the port mapping, given a specific environment variable

So you can run a docker like that :

docker run --add-host=HOST_IP:77.202.XXX.YYY --env HOST_PORT_8545=8046 -it besu-dev:latest --p2p-enabled=true --rpc-http-enabled --rpc-http-apis="eth,net,web3,debug,admin"

[RatanRSur]

While in the process of reviewing it, I made some changes to see if we needed a separate AutoDetectionResult. Take a look at the PR I made against your branch and let me know if you think it's a good change.

I still need to look at the specifics of the Docker advertised port logic and testing.

[matkt]

While in the process of reviewing it, I made some changes to see if we needed a separate AutoDetectionResult. Take a look at the PR I made against your branch and let me know if you think it's a good change.

I still need to look at the specifics of the Docker advertised port logic and testing.

LGTM. I validated the modification. Don't hesitate to tell me if you have any questions

[RatanRSur]

Just had had one question about finding the host ip.