docker - Docker Ubuntu 18.04 SSH key 扫描

Question

希望有人可能已经解决了这个问题。

我想将docker镜像从Ubuntu 16.04升级到Ubuntu 18.04。
除了以下几点，其他一切似乎都很好:

RUN apt-get install -y ssh
RUN mkdir -p /home/sshkeys
RUN ssh-keygen -q -t rsa -N '' -f /home/sshkeys/id_rsa 
RUN touch /home/sshkeys/authorized_keys
RUN cat /home/sshkeys/id_rsa.pub >> /home/sshkeys/authorized_keys
RUN ./etc/init.d/ssh start
RUN sed -i 's/PermitRootLogin prohibit-password/PermitRootLogin yes/' /etc/ssh/sshd_config     
**RUN ssh-keyscan localhost >> /home/postgres/.ssh/known_hosts**

使用 Ubuntu 16.04可以正常工作，但是在 Ubuntu 18.04中，从 Dockerfile构建图像时出现以下错误:

Step 36/71 : RUN ssh-keyscan localhost >> /home/postgres/.ssh/known_hosts
 ---> Running in 0f34b430fc2f
write (localhost): Connection refused
write (localhost): Connection refused
write (localhost): Connection refused
Removing intermediate container 0f34b430fc2f

Answer 1

您应该在与sshd相同的层中启动ssh-keyscan，默认情况下它不在新层中启动，因此只需在相同的RUN中耦合命令即可:

RUN \
  ./etc/init.d/ssh start && \
  ssh-keyscan localhost >> /home/postgres/.ssh/known_hosts