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Prerequisites

Yaml​

YAML is a human-readable data serialization standard that can be used in conjunction with all programming languages and is often used to write configuration files.

Anchors & Aliases​

The below docker-compose.yml file is using Anchors and Aliases to reduce the duplication of the code. It was aimed to create one master server and six worker servers. Three of them are using ubuntu and the other three are using centos as their base image. To test and Ansible.

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To see Dockerfiles:

Dockerfile.master
FROM ubuntu:22.04

RUN apt update && \
    apt -y upgrade && \
    apt -y dist-upgrade && \
    apt -y install iputils-ping && \
    apt -y install openssh-client && \
    apt -y install ansible && \
    echo 'root:root' | chpasswd && \
    mkdir -p /root/.ssh

RUN echo "Host *" >> /root/.ssh/config && \
    echo "    IdentityFile /root/.ssh/root" >> /root/.ssh/config && \
    echo "    User root" >> /root/.ssh/config && \
    chmod 600 /root/.ssh/config

COPY ./secrets/master_keys/ /root/.ssh/
COPY ./secrets/ansible_keys/ /root/.ssh/

RUN mkdir -p ~/src

COPY ./scripts/init_master.bash /tmp/init.bash
RUN chmod +x /tmp/init.bash

WORKDIR /root/src/

ENTRYPOINT [ "/tmp/init.bash" ]
Dockerfile.worker.ubuntu
FROM ubuntu:22.04

RUN apt update && \
    apt -y upgrade && \
    apt -y dist-upgrade && \
    apt -y install python3-apt && \
    apt -y install openssh-server && \
    apt -y install sudo && \
    rm -rf /var/lib/apt/lists/* && \
    echo 'root:root' | chpasswd && \
    mkdir -p /root/.ssh && \
    ln -sf /usr/share/zoneinfo/UTC /etc/localtime

COPY ./secrets/master_keys/root.pub /tmp/root.pub
RUN cat /tmp/root.pub >> /root/.ssh/authorized_keys && \
    rm /tmp/root.pub

COPY ./scripts/init_ubuntu_worker.bash /tmp/init.bash
RUN chmod +x /tmp/init.bash

ENTRYPOINT [ "/tmp/init.bash" ]
Dockerfile.worker.centos
FROM centos:8

RUN sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-* && \
    sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d/CentOS-* && \
    dnf -y update && \
    dnf -y upgrade && \
    dnf -y install openssh-server && \
    dnf -y install sudo && \
    groupadd sudo && \
    echo 'root:root' | chpasswd && \
    mkdir -p /root/.ssh && chmod 700 /root/.ssh && \
    ln -sf /usr/share/zoneinfo/UTC /etc/localtime && \
    ssh-keygen -q -N '' -t rsa -f /etc/ssh/ssh_host_rsa_key && \
    ssh-keygen -q -N '' -t ecdsa -f /etc/ssh/ssh_host_ecdsa_key && \
    ssh-keygen -q -N '' -t ed25519 -f /etc/ssh/ssh_host_ed25519_key && \
    rm /var/run/nologin

COPY ./secrets/master_keys/root.pub /tmp/root.pub
RUN cat /tmp/root.pub >> /root/.ssh/authorized_keys && \
    rm /tmp/root.pub

COPY ./scripts/init_centos_worker.bash /tmp/init.bash
RUN chmod +x /tmp/init.bash

ENTRYPOINT [ "/tmp/init.bash" ]
version: '3.8'

x-defaults: &default-config
  restart: always
  stdin_open: true
  tty: true
  networks:
    - servers-network

x-worker: &worker
  build:
    context: ./images
    dockerfile: Dockerfile.worker.${WORKER_OS}
  image: ziadmmh/${WORKER_NAME}:v0.0.1
  container_name: ${WORKER_NAME}
  hostname: ${WORKER_NAME}
  ports:
  - "800${WORKER_NUMBER}:80"
  <<: *default-config

services:
  srvmaster:
    build:
      context: ./images
      dockerfile: Dockerfile.master
    <<: *default-config
    image: ziadmmh/srvmaster:v0.0.1
    container_name: srvmaster
    hostname: srvmaster
    volumes:
      - ./volumes:/root/src
    depends_on:
      - srvone
      - srvtwo
      - srvthree
      - srvfour
      - srvfive
      - srvsix
  srvone:
    <<: *worker
    environment: [WORKER_OS=ubuntu, WORKER_NAME=srvone, WORKER_NUMBER=1]
  srvtwo:
    <<: *worker
    environment: [WORKER_OS=centos, WORKER_NAME=srvtwo, WORKER_NUMBER=2]
  srvthree:
    <<: *worker
    environment: [WORKER_OS=ubuntu, WORKER_NAME=srvthree, WORKER_NUMBER=3]
  srvfour:
    <<: *worker
    environment: [WORKER_OS=centos, WORKER_NAME=srvfour, WORKER_NUMBER=4]
  srvfive:
    <<: *worker
    environment: [WORKER_OS=ubuntu, WORKER_NAME=srvfive, WORKER_NUMBER=5]
  srvsix:
    <<: *worker
    environment: [WORKER_OS=centos, WORKER_NAME=srvsix, WORKER_NUMBER=6]

networks:
  servers-network:
    name: servers-network