Testing an issue in Docker
Do requests made from one Docker container to another on a Docker Machine behave the same as requests made from one Docker container to a server on the host?
Also, does it matter if it's on Docker or on the host OS?
Setup
brew update
brew reinstall docker docker-machine docker-compose
docker-machine create default --driver virtualbox
pip3 install -r requirements.txt # `brew update && brew install python3` to get pip3
Testing within machine
You're in a docker container and you need to communicate to a server running in a separate container on the same host OS.
First, get the server up, since it takes time to start up.
docker-compose -f within-machine.yml build
docker-compose -f within-machine.yml up -d server
Then, run the emitter.
docker-compose -f within-machine.yml up emitter
Results:
dockerprob_server_1 is up-to-date
Recreating dockerprob_emitter_1
Attaching to dockerprob_emitter_1
emitter_1 |
emitter_1 | Total Time: 0.008154
dockerprob_emitter_1 exited with code 0
Testing across machine
You're in a docker container and you need to communicate to a server running on the host OS from within a container on a Docker Machine.
In one terminal on the host machine,
hug -f server.py -p 8002
In another terminal, first provide SERVER_URL. Here, I'm assuming you're on a mac, figure out how to provide hostip on your own machine if it's different.
alias hostip='ifconfig en0 | grep "inet\ " | cut -d: -f2 | cut -d" " -f2'
export SERVER_URL="http://`hostip`:8002"
Now, you're ready to build and run the emitter.
docker-compose -f across-machine.yml build
docker-compose -f across-machine.yml up emitter
Results:
Recreating dockerprob_emitter_1
Attaching to dockerprob_emitter_1
emitter_1 |
emitter_1 | Total Time: 0.017632
dockerprob_emitter_1 exited with code 0
Testing outside Docker
You're on the host OS and you need to communicate to some server on the host OS.
In one terminal,
hug -f server.py -p 8003
In another terminal,
SERVER_URL=http://127.0.0.1:8003 python3 emitter.py
Results:
Total Time: 0.022352
My system
OS X 10.11.5
VBoxManage version: 5.0.22r108108
Docker version 1.11.2, build b9f10c9
docker-compose version 1.7.1, build unknown
docker-machine version 0.7.0, build a650a40