Connect Julia from inside Docker to outside

inside_docker.jl

## Start the docker container:
# docker run -dit -p 9009:9009 --name mytest julia:1.0
## Enter the docker container
# docker exec -it mytest bash

using Sockets; l = listen(IPv4(0),9009); accept(l)
## Expected output
# (Blocks until a connection comes thru)
# TCPSocket(RawFD(0x00000014) open, 0 bytes waiting)

outside_docker.jl

using Sockets; connect(9009)

# TCPSocket(RawFD(0x00000016) open, 0 bytes waiting)

## Verify the connection using netstat
# netstat -ac | grep 9009
# netstat -ac | grep tcp4