how to connect to remote host running in docker container from jenkins running in docker container using ssh - linux

Question

I have tried these steps a number of time but failing. Did lot of RnD but could not fix the issue.
I am using CentOS running on Oracle VM.
I am trying to connect from CentOS host -> Jenkins -> Remote Host using SSH
My present working directory is : /root/connect2nareshc/jenkins_0_to_hero/jenkins_image
I did ssh-keygen -f remote-key to generate public and private keys.
In the directory /root/connect2nareshc/jenkins_0_to_hero/jenkins_image I have Dockerfile as follows:
FROM centos:7
RUN yum -y install openssh-server
RUN useradd remote_user && \
echo "1234" | passwd remote_user --stdin && \
mkdir /home/remote_user/.ssh && \
chmod 700 /home/remote_user/.ssh
COPY remote-key.pub /home/remote_user/.ssh/authorized_keys
RUN chown remote_user:remote_user -R /home/remote_user/.ssh && \
chown 600 /home/remote_user/.ssh/authorized_keys
RUN ssh-keygen -A
CMD /usr/sbin/sshd -D
In one directory above in /root/connect2nareshc/jenkins_0_to_hero, I have docker-compose.yml as follows:
version: '3'
services:
jenkins:
container_name: jenkins_yml
image: "jenkins/jenkins:lts"
ports:
- 8080:8080
networks:
- net
remote_host:
container_name: remote-host
image: remote_host
build:
context: /root/connect2nareshc/jenkins_0_to_hero/jenkins_image
networks:
- net
networks:
net:
I execute the following command and it works fine. I.e. From host I connect to Jenkins and from Jenkins I connect to remote_host using password.
docker-compose build
docker-compose up -d
docker exec -it jenkins_yml bash
ssh remote_user#remote_host
#Enter password 1234 when prompted.
When I try to connect using keys, I am not able to:
docker cp remote-key jenkins_yml:/tmp/remote-key
docker exec -it jenkins_yml bash
cd /tmp
ssh -i remote-key remote_user#remote_host
Instead it prompts me to connect with password.
While on remote_host I did ls -altr on /var/log and got following output. I cannot find auth.log
drwxr-xr-x. 1 root root 4096 May 4 15:36 ..
-rw-r--r--. 1 root root 193 May 4 15:36 grubby_prune_debug
-rw-------. 1 root utmp 0 May 4 15:36 btmp
drwxr-xr-x. 1 root root 4096 May 4 15:37 .
-rw-------. 1 root root 1751 Jul 28 16:35 yum.log
-rw-------. 1 root root 64064 Jul 28 16:36 tallylog
-rw-rw-r--. 1 root utmp 1152 Jul 29 03:17 wtmp
-rw-r--r--. 1 root root 292292 Jul 29 03:17 lastlog