Set DOCKER_HOST_IP environment variable automatically #2915
Description
My use case is that I'm running docker-compose on a Mac so when I do docker-compose port, by default it returns 0.0.0.0 as the IP address, which is not useful if you're on a Mac and trying to contact a service on the Docker host.
Example:
I have a docker-compose.yml that looks like this:
version: '2'
services:
anonweb:
...
ports:
- ":8000"
...Now I do:
[marca@marca-mac2 smdevstack]$ docker-compose up -d
Recreating smdevstack_anonweb_1
[marca@marca-mac2 smdevstack]$ docker-compose ps
Name Command State Ports
---------------------------------------------------------------------------------------
smdevstack_anonweb_1 gunicorn --paste=/appinifi ... Up 0.0.0.0:32777->8000/tcp
[marca@marca-mac2 smdevstack]$ docker-compose port anonweb 8000
0.0.0.0:32777
[marca@marca-mac2 smdevstack]$ http $(docker-compose port anonweb 8000)/status/pid
http: error: ConnectionError: HTTPConnectionPool(host='0.0.0.0', port=32777): Max retries exceeded with url: /status/pid (Caused by NewConnectionError('<requests.packages.urllib3.connection.HTTPConnection object at 0x10363fa50>: Failed to establish a new connection: [Errno 61] Connection refused',)) while doing GET request to URL: http://0.0.0.0:32777/status/pid
Connecting to 0.0.0.0:32777 of course from the Mac is not useful.
So instead I'd like to use make the container bind to the real IP address of the Docker machine. I change my docker-compose.yml to the following:
version: '2'
services:
anonweb:
...
ports:
- "${DOCKER_HOST_IP}::8000"
...This in itself accomplishes nothing because DOCKER_HOST_IP is not set:
[marca@marca-mac2 smdevstack]$ docker-compose up -d
WARNING: The DOCKER_HOST_IP variable is not set. Defaulting to a blank string.
Starting smdevstack_anonweb_1
[marca@marca-mac2 smdevstack]$ docker-compose ps
WARNING: The DOCKER_HOST_IP variable is not set. Defaulting to a blank string.
Name Command State Ports
---------------------------------------------------------------------------------------
smdevstack_anonweb_1 gunicorn --paste=/appinifi ... Up 0.0.0.0:32779->8000/tcp
[marca@marca-mac2 smdevstack]$ docker-compose port anonweb 8000
WARNING: The DOCKER_HOST_IP variable is not set. Defaulting to a blank string.
0.0.0.0:32779
[marca@marca-mac2 smdevstack]$ http $(docker-compose port anonweb 8000)/status/pid
WARNING: The DOCKER_HOST_IP variable is not set. Defaulting to a blank string.
http: error: ConnectionError: HTTPConnectionPool(host='0.0.0.0', port=32779): Max retries exceeded with url: /status/pid (Caused by NewConnectionError('<requests.packages.urllib3.connection.HTTPConnection object at 0x103789a50>: Failed to establish a new connection: [Errno 61] Connection refused',)) while doing GET request to URL: http://0.0.0.0:32779/status/pid
It works great if I arrange for DOCKER_HOST_IP to be set.
One nice way to do this is with direnv. Assuming I have direnv installed, I can do this:
[marca@marca-mac2 smdevstack]$ cat > .envrc
export DOCKER_HOST_IP=$(docker-machine ip)
direnv: error .envrc is blocked. Run `direnv allow` to approve its content.
[marca@marca-mac2 smdevstack]$ direnv allow
direnv: loading .envrc
direnv: export +DOCKER_HOST_IP
Now I get this:
[marca@marca-mac2 smdevstack]$ docker-compose up -d
Recreating smdevstack_anonweb_1
[marca@marca-mac2 smdevstack]$ docker-compose ps
Name Command State Ports
----------------------------------------------------------------------------------------------
smdevstack_anonweb_1 gunicorn --paste=/appinifi ... Up 192.168.99.101:32774->8000/tcp
[marca@marca-mac2 smdevstack]$ docker-compose port anonweb 8000
192.168.99.101:32774
[marca@marca-mac2 smdevstack]$ http $(docker-compose port anonweb 8000)/status/pid
HTTP/1.1 200 OK
Connection: close
Content-Length: 112
Content-Type: application/json; charset=UTF-8
Date: Sat, 13 Feb 2016 20:46:16 GMT
SM-Request-ID: 094fe0a4-605c-457f-a0b1-8a97764abcaa
Server: gunicorn/19.4.5
{
"host": "7c8b1a192f27",
"pid": 9,
"reason": "/appenv/enabled.txt does not exist",
"status": "SERVICE_DISABLED"
}
Beautiful!
But now if I want my little docker-compose project to be easily usable by others, I have to tell them to install direnv. Also my solution assumes folks are using docker-machine and maybe they aren't. Maybe they are using straight Docker without Docker Machine and so that docker-machine ip command won't work.
I am asking if docker-compose could simply set that environment variable automatically, perhaps by taking the existing DOCKER_HOST variable and massaging it into a simple IP address.
Then it just works out of the box without requiring direnv.
Reasonable?
Cc: @sudarkoff