#update apk for install
RUN apk update
#install ansible and openssh
RUN apk add ansible openssh
#init ansible hosts file
RUN mkdir -p /etc/ansible
RUN echo "localhost" >/etc/ansible/hosts
#init rsa ssh key pair
RUN ssh-keygen -t rsa -P "" -f ~/.ssh/id_rsa
#delete cache files 
RUN rm -rf /var/cache/apk/*

[root@occluster ~]# docker pull liumiaocn/ansible
Using default tag: latest
Trying to pull repository docker.io/liumiaocn/ansible ... 
latest: Pulling from docker.io/liumiaocn/ansible
ff3a5c916c92: Already exists 
42a81541f983: Pull complete 
86602ac17bcb: Pull complete 
73cb14e49a3f: Pull complete 
bdfcad59d746: Pull complete 
455ffeaa5bf1: Pull complete 
dff32643cfa5: Pull complete 
Digest: sha256:46284f3d3b9e3880f9b65fa6b1fb225b19bc88222badf74aa85936aabc24090f
Status: Downloaded newer image for docker.io/liumiaocn/ansible:latest
[root@occluster ~]# 
[root@occluster ~]# docker images |grep ansible
docker.io/liumiaocn/ansible         latest       8a5cfdf8243f    Less than a second ago  103 MB
[root@occluster ~]#

[root@occluster ~]# docker run -it --name ansible liumiaocn/ansible sh
/ # ansible --version
ansible 2.4.1.0
 config file = None
 configured module search path = [u'/root/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
 ansible python module location = /usr/lib/python2.7/site-packages/ansible
 executable location = /usr/bin/ansible
 python version = 2.7.14 (default, Dec 14 2017, 15:51:29) [GCC 6.4.0]
/ #

/ # ssh-copy-id 192.168.163.172
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
The authenticity of host '192.168.163.172 (192.168.163.172)' can't be established.
ECDSA key fingerprint is SHA256:uh84Xw56LhiCXb1b0uFbX/CoFhkqHGZjtmLwl3qkTOY.
Are you sure you want to continue connecting (yes/no)"ssh '192.168.163.172'"
and check to make sure that only the key(s) you wanted were added.
/ #

/ # ssh 192.168.163.172 hostname
occluster
/ #

/ # echo "192.168.163.172" /etc/ansible/hosts
/ # ansible 192.168.163.172 -m ping
192.168.163.172 | SUCCESS => {
  "changed": false, 
  "failed": false, 
  "ping": "pong"
}
/ #