docker容器中的应用程序无法在同一容器上调用服务

Question

To start my docker container i use :

docker run -p 5001:5001 -p 7777:7777 -i -t --entrypoint /bin/bash dc261bdea451

As can see I'm exposing two ports : 5001 & 7777

nodejs is running on port 5001 & socko server on 7777. From the browser I can access these services directly via http://localhost:5001 & http://localhost:7777 . The nodejs app running on port 5001 makes a call to the service running on port 7777 :

So by invoking http://localhost:5001 a call to http://localhost:7777 is made :

var request = require('request');
request("http://localhost:7777?param=param....

The issue is service running on port 7777 is not being invoked. I also tried :

var request = require('request');
request("http://127.0.0.1:7777?param=param....

but same result.

This issue does not occur when I run the apps outside of docker container.

Is there a config option I'm missing that allows two servers running on one docker container to communicate ?

Update :

Changing the hostname to IP address of machine docker container is running on reaches the endpoint. So changing this works :

var request = require('request');
request("http://localhost:7777?param=param....

to

var request = require('request');
request("http://my.ip.address:7777?param=param....

But this is not a solution as it requires an update to the container after it's deployed.

Answer 1

1. You do not need to use port mapping ( -p flag) to allow container internal communication. This is only required when you want to connect from your host to the container.
2. In general it is recommended to only run one process per container. You might want to look at running the two processes in different containers and link them via Docker networking.

Anyway, to investigate the issue start a bash in your container to validate the service on port 7777 is reachable from within the container ( docker exec -it <container_id> bash , telnet localhost 7777 ). In case it is not listening you need to check that it is binding to the correct hostname.