Start sshd automatically with docker container

Question

Given:

• container based on ubuntu:13.10
• installed ssh (via apt-get install ssh)

Problem: each when I start container I hav

Answer 1

Here is a Dockerfile which installs ssh server and runs it:

# Build Ubuntu image with base functionality.
FROM ubuntu:focal AS ubuntu-base
ENV DEBIAN_FRONTEND noninteractive
SHELL ["/bin/bash", "-o", "pipefail", "-c"]

# Setup the default user.
RUN useradd -rm -d /home/ubuntu -s /bin/bash -g root -G sudo ubuntu
RUN echo 'ubuntu:ubuntu' | chpasswd
USER ubuntu
WORKDIR /home/ubuntu

# Build image with Python and SSHD.
FROM ubuntu-base AS ubuntu-with-sshd
USER root

# Install required tools.
RUN apt-get -qq update \
    && apt-get -qq --no-install-recommends install vim-tiny=2:8.1.* \
    && apt-get -qq --no-install-recommends install sudo=1.8.* \
    && apt-get -qq --no-install-recommends install python3-pip=20.0.* \
    && apt-get -qq --no-install-recommends install openssh-server=1:8.* \
    && apt-get -qq clean    \
    && rm -rf /var/lib/apt/lists/*

# Configure SSHD.
# SSH login fix. Otherwise user is kicked off after login
RUN sed 's@session\s*required\s*pam_loginuid.so@session optional pam_loginuid.so@g' -i /etc/pam.d/sshd
RUN mkdir /var/run/sshd
RUN bash -c 'install -m755 <(printf "#!/bin/sh\nexit 0") /usr/sbin/policy-rc.d'
RUN ex +'%s/^#\zeListenAddress/\1/g' -scwq /etc/ssh/sshd_config
RUN ex +'%s/^#\zeHostKey .*ssh_host_.*_key/\1/g' -scwq /etc/ssh/sshd_config
RUN RUNLEVEL=1 dpkg-reconfigure openssh-server
RUN ssh-keygen -A -v
RUN update-rc.d ssh defaults

# Configure sudo.
RUN ex +"%s/^%sudo.*$/%sudo ALL=(ALL:ALL) NOPASSWD:ALL/g" -scwq! /etc/sudoers

# Generate and configure user keys.
USER ubuntu
RUN ssh-keygen -t ed25519 -f ~/.ssh/id_ed25519
#COPY --chown=ubuntu:root "./files/authorized_keys" /home/ubuntu/.ssh/authorized_keys

# Setup default command and/or parameters.
EXPOSE 22
CMD ["/usr/bin/sudo", "/usr/sbin/sshd", "-D", "-o", "ListenAddress=0.0.0.0"]

Build with the following command:

docker build --target ubuntu-with-sshd -t ubuntu-with-sshd .

Then run with:

docker run -p 2222:22 ubuntu-with-sshd

To connect to container via local port, run: ssh -v localhost -p 2222.

To check for container IP address, use docker ps and docker inspect.

---

Here is example of docker-compose.yml file:

---
version: '3.4'
services:
  ubuntu-with-sshd:
    image: "ubuntu-with-sshd:latest"
    build:
      context: "."
      target: "ubuntu-with-sshd"
    networks:
      mynet:
        ipv4_address: 172.16.128.2
    ports:
      - "2222:22"
    privileged: true # Required for /usr/sbin/init
networks:
  mynet:
    ipam:
      config:
        - subnet: 172.16.128.0/24

To run, type:

docker-compose up --build