Support for communicating with Docker over TCP

[ryfow]

I'm trying to set up the nginx reverse proxy as a docker container.

To do that, it'd be nice if docker-gen supported the DOCKER_HOST environment variable or a command-line parameter specifying how to communicate with Docker.

[thaJeztah]

+1 Was just trying to achieve the same thing to test this thing out

Communicating via TCP should not be required, mounting docker.sock inside the container should work, e.g.:

docker run -v /var/run/docker.sock:/docker.sock ….

Note that mounting docker.sock inside a container at /var/run/ does not work, other locations do (for example /docker.sock). Currently, the location of docker.sock is hardcoded inside https://github.com/jwilder/docker-gen/blob/master/docker-gen.go#L213 and https://github.com/jwilder/docker-gen/blob/master/docker_client.go#L43

I tried to change those lines and re-build docker-gen but couldn't get it to work. Only spent a couple of minutes so maybe it's just my lack of go-experience or a misconfiguration of the docker-gen parameters.

@jwilder any chance on providing a Dockerized nginx proxy on index.docker.io? (preferably a 'trusted build')

I like the simplicity of your software for simple development stuff (compared to more advanced systems like skydock etc).

[jwilder]

@ryfow I agree. The hard-coded unix domain socket is not ideal.

[jwilder]

@thaJeztah I'll look into getting docker-gen to run as a container. I have not tried that since I usually just run it on the host. An trusted build would be convenient though.

[thaJeztah]

@jwilder thanks a lot in advance! Now that I got the 'hang' of docker, I'd like keep my host clean, especially when testing new software :)

[jwilder]

I pushed some changes to master that add support for DOCKER_HOST as well as a new -endpoint flag via the command-line. The format is tcp://127.0.0.1:4243 or unix:///var/run/docker.sock.

[cer]

As far as I can tell the -endpoint flag will always ignored:

if endpoint == "" && os.Getenv("DOCKER_HOST") != "" {
    endpoint = os.Getenv("DOCKER_HOST")
} else {
    endpoint = "unix:///var/run/docker.sock"
}

[jwilder]

@cer You're right. Should be fixed now.

[jwilder]

@thaJeztah Created a trusted build: https://index.docker.io/u/jwilder/nginx-proxy/ Can you give it a try?

[bradleyg]

This works really well!

[ekristen]

Works for me.

[thaJeztah]

@jwilder Not really sure what the problem is on my side; I'm running a container that exposes two ports (22 and 80) nginx-proxy tries to use port 22 (i.e. the 49xxx port that is assigned for port 22) as the upstream port.

If I don't expose port 22, nginx-proxy doesn't pick-up the port and tries to use http://ip-address: (note the trailing :) as the upstream address.

When exposing both port 22 and 80:

2014/05/08 17:21:56 [error] 30#0: *1 upstream sent no valid HTTP/1.0 header while reading response header from upstream, client: xxx.xxx.xxx.xxx, server: somedomainname.tld, request: "GET / HTTP/1.1", upstream: "http://172.17.42.1:49232/", host: "somedomainname.tld"

2014/05/08 17:21:56 [error] 30#0: *1 readv() failed (104: Connection reset by peer) while reading upstream, client: xxx.xxx.xxx.xxx, server: somedomainname.tld, 
request: "GET / HTTP/1.1", upstream: "http://172.17.42.1:49232/", host: "somedomainname.tld"

Which is to be expected, since this is the SSH port.

If I only expose port 80;

2014/05/08 15:44:48 [emerg] 38#0: invalid port in upstream "172.17.42.1:" in /etc/nginx/sites-enabled/default:6

And this is the configuration that was generated;

upstream somedomainname.tld {
        server 172.17.42.1:;
}

server {
        gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript;

        server_name somedomainname.tld;

        location / {
            proxy_pass http://somedomainname.tld;
            include /etc/nginx/proxy_params;
        }
}

_Note:_

Replaced the actual domain-name with 'somedomainname.tld'. I'm using a '.xip.io' domain-name for testing, e.g. something.123.123.123.123.xip.io, but don't think this is related

[jwilder]

@thaJeztah I'll see if I can reproduce that. My guess is that the template is just assuming one port is exposed and this line: https://github.com/jwilder/nginx-proxy/blob/master/nginx.tmpl#L5 is just picking the first address.