How to connect to Docker API from another machine?
I'm trying to use the Docker API to connect to docker daemon from another machine. I am able to do this command successfully:
docker -H=tcp://127.0.0.1:4243 images
But NOT when I use the real IP address:
docker -H=tcp://192.168.2.123:4243 images
2013/08/04 01:35:53 dial tcp 192.168.2.123:4243: connection refused
Why can't I connect when using a non-local IP?
I'm using a Vagrant VM with the following in Vagrantfile: config.vm.network :private_network, ip: "192.168.2.123"
The following is iptables:
# Generated by iptables-save v1.4.12 on Sun Aug 4 01:24:46 2013
*filter
:INPUT ACCEPT [1974:252013]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [1511:932565]
-A INPUT -p tcp -m tcp --dport 4243 -j ACCEPT
COMMIT
# Completed on Sun Aug 4 01:24:46 2013
# Generated by iptables-save v1.4.12 on Sun Aug 4 01:24:46 2013
*nat
:PREROUTING ACCEPT [118:8562]
:INPUT ACCEPT [91:6204]
:OUTPUT ACCEPT [102:7211]
:POSTROUTING ACCEPT [102:7211]
:DOCKER - [0:0]
-A PREROUTING -m addrtype --dst-type LOCAL -j DOCKER
-A OUTPUT ! -d 127.0.0.0/8 -m addrtype --dst-type LOCAL -j DOCKER
-A POSTROUTING -s 172.16.42.0/24 ! -d 172.16.42.0/24 -j MASQUERADE
Answer
Came across a similar issue, one thing I don't see mentioned here is you need to start docker to listen to both the network and a unix socket. All regular docker (command-line) commands on the host assume the socket.
sudo docker -H tcp://0.0.0.0:2375 -H unix:///var/run/docker.sock -d &
will start docker listening to any ip address on your host, as well as the typical unix socket.