Start ssh using systemctl inside the docker container - docker

Question

I' m a beginner in the Docker;
I have pulled a CentOS 7 image from Hub and ran it ;
I need to ssh in to the docker container(CentOS 7) from my host.
Got the docker container's IP using docker inspect container-id
I have installed the following using
initscripts
systemd.x86_64
systemd-libs.x86_64
open-ssh
firewalld
net-tools
when i tried to start the firewall to open the port for ssh(22)
[root#a6f3e3eb095c ~]# systemctl start firewall
Failed to get D-Bus connection: Operation not permitted
Also tried,
[root#a6f3e3eb095c ~]# /usr/lib/systemd/systemd --system &
[1] 353
[root#a6f3e3eb095c ~]# systemd 219 running in system mode. (+PAM +AUDIT +SELINUX +IMA -APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ -LZ4 -SECCOMP +BLKID +ELFUTILS +KMOD +IDN)
Detected virtualization xen.
Detected architecture x86-64.
Welcome to CentOS Linux 7 (Core)!
Set hostname to <a6f3e3eb095c>.
Cannot determine cgroup we are running in: No such file or directory
Failed to allocate manager object: No such file or directory
[1]+ Exit 1 /usr/lib/systemd/systemd --system
How to start the firewall/ssh inside the docker container ?

Answer 1

inside docker container run following commands :
yum update -y glibc-common
yum install -y sudo passwd openssh-server openssh-clients tar screen crontabs strace telnet perl libpcap bc patch ntp dnsmasq unzip pax which
rpm -Uvh http://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
yum install -y hiera lsyncd sshpass rng-tools
service sshd start;
sed -i 's/UsePAM yes/#UsePAM yes/g' /etc/ssh/sshd_config;
sed -i 's/#UsePAM no/UsePAM no/g' /etc/ssh/sshd_config;
sed -i 's/#PermitRootLogin yes/PermitRootLogin yes/' /etc/ssh/sshd_config;
sed -i 's/enabled=0/enabled=1/' /etc/yum.repos.d/CentOS-Base.repo
mkdir -p /root/.ssh/;
rm -f /var/lib/rpm/.rpm.lock;
echo "StrictHostKeyChecking=no" > /root/.ssh/config;
echo "UserKnownHostsFile=/dev/null" >> /root/.ssh/config
echo "root:password" | chpasswd
( or )
Simply you can pull docker image of centos with ssh in docker hub
https://hub.docker.com/search/?isAutomated=0&isOfficial=0&page=1&pullCount=0&q=centos+ssh&starCount=0
https://hub.docker.com/r/kinogmt/centos-ssh/
https://hub.docker.com/r/jdeathe/centos-ssh/

Answer 2

You can avoid the "Failed to get D-Bus connection: Operation not permitted" / aka installing systemd inside a docker by using the https://github.com/gdraheim/docker-systemctl-replacement ... after that the docker-exec stuff should be all fine to do things inside a container.

Answer 3

If you really do need an ssh or sftp container, then you can use my Docker Image as a source image for your own or run it directly:
If using the official CentOS-7 Image and you require systemd, there are instructions on how to enable it under the section "Systemd integration".
However, based on the following:
I need to ssh in to the docker container(CentOS 7) from my host.
You can use docker exec to run commands in a running, (backgrounded), container so, for images that have bash available, you can access an interactive tty and run bash as follows from your host - where container can be either the name or id:
docker exec --tty --interactive <container> bash
OR
docker exec -ti <container> bash
Finally, it's unlikely to be necessary to install the firewall package in your image as the operator will decide what ports to publish from those which are exposed and you can make use of Docker Networking to only expose the necessary public facing services.

Answer 4

If you are using the Docker CLI, then you can get into the Docker container using the following command
docker exec -it containerId bash
I am not sure how to ssh into the docker container, but if you want to do basic operation inside the Docker container, you can make use of the above docker command.