how to change configuration of freeradius-server in docker container? - docker

Question

I'm trying to bulid a freeradius-server using docker and pull a image "freeradius/freeradius server". The first time I used given command
docker run --name my-radius -t -d freeradius/freeradius-server -X
to build a containner adn successfully start debug mode. But I don't know how to quit so I used ctrl+c to stop the containner. And then I used commands below to get in the containner and want to start debug mode again so that I can change configuration or parameters.
docker start my-radius
docker exec -it my-radius /bin/bash
I got in the containner and used freeradius -X but failed. It present
Failed binding to auth address 127.0.0.1 port 18120 bound to server inner-tunnel: Address already in use
/etc/freeradius/sites-enabled/inner-tunnel[33]: Error binding to port for 127.0.0.1 port 18120
I used Google to look for solutions but failed. I guess it means the radius-server started automatically so that the address 127.0.0.1 and port 18120 were used. But I don't know how to stop it in the containner .

Answer 1

The official FreeRADIUS docker image will start FreeRADIUS when the container starts. This means that if you start the container and then exec a shell into it, FreeRADIUS will already be running.
The container will exit as soon as the FreeRADIUS process stops, meaning it is not possible to start the container in this way, stop FreeRADIUS running, and then continue to use the container.
In this situation, trying to run FreeRADIUS a second time in another shell will fail because the ports are already open, as you have discovered.
This can be see thus:
$ docker run --name my-radius -d freeradius/freeradius-server
106cdbc81e8e5c0257f22bebad221ed1b4ba0a14f40ce1e4110ec388380c7e62
$ docker exec -it my-radius /bin/bash
root#106cdbc81e8e:/# ps -ef
UID PID PPID C STIME TTY TIME CMD
freerad 1 0 1 23:10 ? 00:00:00 freeradius -f
root 12 0 1 23:10 pts/0 00:00:00 /bin/bash
root 22 12 0 23:10 pts/0 00:00:00 ps -ef
root#106cdbc81e8e:/# exit
exit
$ docker stop my-radius
my-radius
$ docker rm my-radius
my-radius
$
To be able to run FreeRADIUS yourself you can do two things. Firstly, don't start the container in the background, but start it in the foreground with FreeRADIUS in debug mode. The docker entrypoint will let you pass arguments directly to the daemon. This is the easiest way if you don't need to actually do anything inside the container, but just run FreeRADIUS in debug mode:
$ docker run --name my-radius -it freeradius/freeradius-server -X
FreeRADIUS Version 3.0.21
Copyright (C) 1999-2019 The FreeRADIUS server project and contributors
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE
...
Listening on auth address * port 1812 bound to server default
Listening on acct address * port 1813 bound to server default
Listening on auth address :: port 1812 bound to server default
Listening on acct address :: port 1813 bound to server default
Listening on auth address 127.0.0.1 port 18120 bound to server inner-tunnel
Listening on proxy address * port 38640
Listening on proxy address :: port 49445
Ready to process requests
^C$
(note hit Ctrl-C to quit).
The alternative is to start it in the background, but instead of running FreeRADIUS run some other process. You can then exec into the container and run FreeRADIUS manually. This means you get a full shell inside the container without FreeRADIUS already running. For instance:
$ docker run --name my-radius -d freeradius/freeradius-server sleep 999999999999
23b5ddd4825a31a8fb417e1594028c6533267be4ff20a448d3844203b805dbd9
$ docker exec -it my-radius /bin/bash
root#23b5ddd4825a:/# ps -ef
UID PID PPID C STIME TTY TIME CMD
root 1 0 0 23:16 ? 00:00:00 sleep 999999999999
root 7 0 0 23:17 pts/0 00:00:00 /bin/bash
root 17 7 0 23:17 pts/0 00:00:00 ps -ef
root#23b5ddd4825a:/# freeradius -X
FreeRADIUS Version 3.0.21
Copyright (C) 1999-2019 The FreeRADIUS server project and contributors
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE
...
Listening on proxy address * port 46662
Listening on proxy address :: port 40284
Ready to process requests
^Croot#23b5ddd4825a:/# exit
exit
$ docker container kill my-radius
my-radius
$ docker container rm my-radius
my-radius
The sleep command used here will obviously quit at some point, so use a number large enough that it runs for long enough, as when that process exits the container will shut down.