Apache Httpd Webserver configuration on Docker using Ansible(by updating inventory with container’s IP)

Objective

Configuration of Apache Httpd Webserver on Docker container using Ansible by dynamic addition of container’s IP address to the inventory file.

Content of this Blog

  • Prerequisite
  • Project Understanding : Ansible Roles Setup
  • Output

Prerequisites

  • For Ansible, refer the following link:
  • For Docker, refer the following link:
  • For Apache Http, refer the following link:

Project Understanding : Ansible Roles Setup

Let’s understand each Ansible role implementation one by one

Part 1: Ansible Role (container_creation)

tasks : main.yml

---
# tasks file for container_creation
- name: Mount Directory Creation
file:
state: directory
path: "{{ mount_directory }}"
- name: Mount Directory to CDROM
mount:
src: "/dev/cdrom"
path: "{{ mount_directory }}"
state: mounted
fstype: "iso9660"
- name: Yum Repository - AppStream
yum_repository:
baseurl: "{{ mount_directory }}/AppStream"
name: "dvd1"
description: "Yum Repository - AppStream"
enabled: true
gpgcheck: no
- name: Yum Repository - BaseOS
yum_repository:
baseurl: "{{ mount_directory }}/BaseOS"
name: "dvd2"
description: "Yum Repository - BaseOS"
enabled: true
gpgcheck: no
- name: Docker Repository Setup
yum_repository:
baseurl:
https://download.docker.com/linux/centos/7/x86_64/stable/
name: "docker"
description: "Docker Repository"
enabled: true
gpgcheck: no
- name: Check whether Docker is installed or not
command: "rpm -q docker-ce"
register: docker_check
- name: Docker Installation
command: "yum install docker-ce --nobest -y"
when: '"is not installed" in docker_check.stdout'
- name: Starting Docker Service
service:
name: "docker"
state: started
enabled: yes
- name: Python3 Installation
package:
name: "python36"
state: present
- name: Installation of Docker SDK for Python
pip:
name: "docker-py"
- name: Changing SELinux state to permissive
selinux:
policy: targeted
state: permissive
- name: Stopping Firewall
service:
name: "firewalld"
state: stopped
- name: DockerHub Login
docker_login:
username: "{{ dockerhub_username }}"
password: "{{ dockerhub_password }}"
- name: Build Directory Creation
file:
path: /root/dockerfile
state: directory
- name: Copying Dockerfile to the Build Directory
copy:
src: files/Dockerfile
dest: /root/dockerfile/Dockerfile
- name: Building Image from Dockerfile and pushing it to DockerHub
community.docker.docker_image:
build:
path: /root/dockerfile
name: "{{ dockerhub_username }}/centos_ssh"
tag: v1
push: yes
source: build
- name: Creation of container from the image created
docker_container:
name: centos_ssh_container
image: "{{ dockerhub_username }}/centos_ssh:v1"
pull: yes
detach: yes
state: started
ports:
- "{{ port_number }}:80"
register: container_info
- name: Retrieving Container IP
shell: echo '{{container_info["ansible_facts"]["docker_container"]["NetworkSettings"]["IPAddress"] }}'
register: container_ip
- name: Adding Container IP to the inventory file
template:
src: templates/inventory.yml
dest: /etc/inventory.yml
- name: Removing EDCSA key from known_hosts file
lineinfile:
path: /root/.ssh/known_hosts
state: absent
regexp: "ecdsa-sha2-nistp256"

Important Points

  • Mount directory is created along with repository for Yum and Docker.
  • Docker is installed and respective service are enabled.
  • Python 3.6 is installed, also Python SDK for Docker is installed as it is required for usage of Docker modules in Ansible.
  • SELinux state is changed to permissive to avoid hindrance in Docker container creation using Ansible modules. Also Firewall is disabled so web page to be set up in the next part could be accessed from outside as well.
  • Docker image are built using Dockerfile(mentioned below) and then pushed to DockerHub. Container from the same is created with SSH connectivity set up within it, also port 80 used for webserver is exposed using the concept of PAT(Port Address Translation).
  • Container’s IP address is retrieved and dynamically placed in the inventory file. Also EDCSA key is removed from known_hosts file present in Docker Host to avoid issues in accessing the new container generated via SSH for Ansible.

Note: In order to use “community.docker.docker_image” module, run the command mentioned below:

ansible-galaxy collection install community.docker

files : Dockerfile

FROM centos:latest
RUN yum install openssh-server -y
RUN echo "PasswordAuthentication yes" >> /etc/ssh/sshd_config
RUN echo "root:centos" | chpasswd
RUN ssh-keygen -A
CMD ["/usr/sbin/sshd","-D"]
EXPOSE 22

Important Points

  • CentOS is used as base image and openssh-server is installed to set up SSH.
  • Password Authentication is enabled and mentioned in SSH configuration file.
  • Password value is mentioned i.e., “centos” and generates host keys using ssh-keygen.
  • sshd service is enabled and port 22 is exposed.

vars : main.yml

---
# vars file for container_creation
mount_directory: "/dvd1"
dockerhub_username: XXXX
dockerhub_password: XXXX
port_number: "80"

Important Points

  • Name of directory to be mounted is mentioned.
  • Username and password required to login to DockerHub so as to push the image created is mentioned.
  • Port number is mentioned for PAT(Port Address Translation) for the Apache Httpd webserver setup within the container.

templates : inventory.yml

[container]
{{ container_ip.stdout }} ansible_ssh_user=root ansible_ssh_pass=centos

Important Points

  • container_ip” variable is mentioned in the file using Jinja2 templating.
  • The value of the variable is obtained by retrieving the IP address of container created.

— — — — — — — — — — — — — — — — — — — — — — — — —

Part 2: Ansible Role (container_webserver_setup)

tasks : main.yml

---
# tasks file for container_webserver_setup
- name: Httpd Installation
package:
name: "httpd"
state: present
register: httpd_install_status
- name: Web Page Setup
copy:
dest: "/var/www/html/index.html"
src: "files/index.html"
- name: Starting Httpd Service
command: "/usr/sbin/httpd"
changed_when: httpd_install_status.changed == true

Important Points

  • httpd is installed in the container accessed via SSH by the Ansible using the inventory file updated in the previous role after container is created.
  • Webpage to be accessed via webserver are copied from the files directory to the Document Root within the container.
  • httpd service is enabled only when the state of “Httpd Installation” changes.

files : index.html

<b>Hello from Container</b>

Output

Usage of Virtual Machine’s IP Address to access the web page launched within Docker container
curl command used to access the content of web page using Docker container’s IP within Virtual Machine

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