How to build a centos7 docker image with a telnet server？

Question

I'm trying to build a centos7 docker image with telnet server. But I don't know how to enable telnet server in it, because systemctl doesn't work in docker.

Answer 1

You can directly use command xinetd to start, not depends on systemd.

Next is the dockerfile and related files, you can build it by yourself.

Dockerfile:

FROM centos:7

RUN yum install -y xinetd && yum install -y telnet-server
COPY telnet /etc/xinetd.d/telnet
COPY docker-entrypoint.sh /
RUN chmod 777 docker-entrypoint.sh

ENTRYPOINT ["/docker-entrypoint.sh"]

telnet:

service telnet
{
    flags = REUSE
    socket_type = stream
    wait = no
    user = root
    server = /usr/sbin/in.telnetd
    log_on_failure += USERID
    disable = no
}

docker-entrypoint.sh:

#!/bin/bash

xinetd -dontfork -stayalive

Answer 2

You could give it a try with the docker-systemctl-replacement script.

Answer 3

Did you try the steps given here ? The link has options with python example too.

https://kagarlickij.com/running-telnet-docker-container/