I have several web apps running in docker on a ubuntu host. Each app is listening on a different port. When inside any container in the docker network, I can connect and receive data from the service, however, when running a request from the host, I can connect successfully, but no data is received. Why aren't the services returning any data when I connect to them from outside the container???
Docker reports this under "PORTS" when I run docker ps:
0.0.0.0:8080->8080/tcp, :::8080->8080/tcp
and netstat reports that the server is listening on that port:
$ netstat -anp | grep 8080
(Not all processes could be identified, non-owned process info
will not be shown, you would have to be root to see it all.)
tcp 0 0 0.0.0.0:8080 0.0.0.0:* LISTEN -
tcp6 0 0 :::8080 :::* LISTEN -
However, when I visit localhost:8080 in my browser (I tried both firefox and chrome), the browser hangs, as if it is connected, but no data is being sent. Similarly, curl hangs forever:
$ curl -vvv localhost:8080
* Uses proxy env variable no_proxy == 'localhost,127.0.0.1,::1'
* Trying 127.0.0.1:8080...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 8080 (#0)
> GET / HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.68.0
> Accept: */*
>
^C
I also tried connecting to it with telnet with a similar result.
I tried running a quick http server directly on the host, and it works fine:
python3 -m http.server 8000
$ curl -vvv localhost:8000
* Uses proxy env variable no_proxy == 'localhost,127.0.0.0/8,::1'
* Trying 127.0.0.1:8000...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 8000 (#0)
> GET / HTTP/1.1
> Host: localhost:8000
> User-Agent: curl/7.68.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
* HTTP 1.0, assume close after body
< HTTP/1.0 200 OK
< Server: SimpleHTTP/0.6 Python/3.8.13
< Date: Fri, 09 Dec 2022 12:36:03 GMT
< Content-type: text/html; charset=utf-8
< Content-Length: 16768
<
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
...
I also tried connecting to the docker container ip: (172.17.0.3:8080) with the same results.
However, when I try running curl inside one of the containers, I am able to reach the http endpoints in any container.
All of this leads me to believe that there is a problem with the docker networking on my host (docker bridge?).
I am using docker compose. Docker inspect reports the following (in part):
"HostConfig": {
"Binds": [],
...
"NetworkMode": "docker-compose-example_default",
"PortBindings": {
"8080/tcp": [
{
"HostIp": "",
"HostPort": "8080"
}
]
},
...
"NetworkSettings": {
"Bridge": "",
"SandboxID": "1b53a5b6580187b714c6d7d0c9f81a015d585cd0bb0d62da579a4fe7514d47ea",
"HairpinMode": false,
"LinkLocalIPv6Address": "",
"LinkLocalIPv6PrefixLen": 0,
"Ports": {
"8080/tcp": [
{
"HostIp": "0.0.0.0",
"HostPort": "8080"
},
{
"HostIp": "::",
"HostPort": "8080"
}
]
},
"SandboxKey": "/var/run/docker/netns/1b53a5b65801",
"SecondaryIPAddresses": null,
"SecondaryIPv6Addresses": null,
"EndpointID": "",
"Gateway": "",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"IPAddress": "",
"IPPrefixLen": 0,
"IPv6Gateway": "",
"MacAddress": "",
"Networks": {
"docker-compose-example_default": {
"IPAMConfig": null,
"Links": null,
"Aliases": [
"dc0813038a3b",
"adminer"
],
"NetworkID": "65c6700f5445a6ce0f98a0a4e14e3e10577f40706411f639a4f9da5b1cfdd52e",
"EndpointID": "0f42ae8ce893fb4f33168c31df0d5de38d2e8ca67521802ba76589a8a0cb1bea",
"Gateway": "172.17.0.1",
"IPAddress": "172.17.0.3",
"IPPrefixLen": 16,
"IPv6Gateway": "",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"MacAddress": "02:42:ac:11:00:03",
"DriverOpts": null
}
}
}
Recap: I can connect to these services inside the containers, but I cannot connect to them from the host, even though by all reports, the servers are listening for connections.
What do I need to do so that I can connect to services running inside docker from my host?
